C++ Programming Derek Banas English (auto-generated) Turkish

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English Anand

well hello internet and welcome to my

Peki merhaba ...

C++ programming tutorial in this tutorial I'm going to teach the entire C++ programming language in one video in the description underneath the video

you're gonna see links to all the individual parts so that should help you get it to exactly what you want and I'm not gonna waste any time covering

installation if you guys want me to cover that just leave a comment down below and I'll do that later so I have a lot to do so let's get into it okay so

what I have here on the left side of the screen is a basic text editor what I have here on the right side of screen is a terminal everything's gonna be exactly

the same as long as you use g plus plus

to compile your programs no matter if you're on Mac Windows or on a Linux operating system so the very first thing we're gonna do here is cover comments

this is a comment just like many other languages you can create a comment just by putting two dashes and then whatever you want and if you want a multi-line

comment you can just type in multi-line and then close that off though there is commenting and c++ first thing we're going to do here is include some outside

libraries are gonna have some functions that we're gonna want to use so this one's going to allow us to use function called C out and a whole bunch of other

different things you're gonna see here in a second that'll be used for vectors this will be used for strings and then this will be used for file i/o now all

of your code is going to be contained inside of a main function like this and then you're gonna have a curly bracket and then you have a closing curly

bracket now inside of here you could call the function C out either using C out or STD C out like this what I want to do is get rid of this part and how I

get rid of that is right here right after the include statement so I'm gonna type in using namespace STD keep me from having to type that out every single

time now if you wanted to do a basic hello world type of statement here all we're gonna have to do is type in hello world using C out which outputs the text

that we have here and a carriage return whenever we type in the same brackets you see right there and ndele that's for the carriage return and this right here

saying we went out to put this on our screen you know the other thing we need to do here is call return 0 you're always going to do this and 0 stands for

the execution went through a perfect we find so just to keep everything simple jump over here in the terminal and this is the command I'm going to use

to run this it's called see Tut and make sure with your C++ programs you always end them with CPP X the extension then right here I'm saying that I want to use

the version 11 of C++ I'm going to compile that and then to run it I'm gonna put period for it slash a dot out if you're on Windows you would just type

in a and you can see hello world prints out rate like that so the next thing we want to discuss here are variables and data types

now variables start with a letter and can contain of course additional letters numbers or underscores but they must start off with the letter and here we're

going to actually create a constant variable which is going to be of type datatype double which means that it contains floating-point numbers or

decimal places and here we're gonna give it the value of 3.14159265 35 and once again constant being here just means that this value cannot be changed and

normally whenever you define constant variables you make their names in all upper cases other data types that are available to you are characters which

contain just one character and they are going to be surrounded by single quotes so let's say I have a grade equal to and a write like that and there you go and a

character very specifically is going to take up one byte inside of memory boolean s-- which normally start with is whenever you're defining the variable

name can contain true which is going to be comfortable to 1 or false which is going to be comparable to a 0 in Saur integers are just whole numbers without

decimal places floats are floating-point numbers just like doubles and they normally are accurate up to 6 decimal places it's

just a favorite number and just copy this guy and doubles of course like I said before are also floating-point numbers but they tend to be accurate up

to around 15 digits in length and then of course if I want to output one of these variables on the screen I'm gonna use C out again and then I could say

favorite number inside of double quotes and then to output it I just put another bracket inside of their fav num and then of course and L for a character turn in

there you can see favorite number 3.14159 now of course there are other data types that are available we have short ends which are going to be at

least 16 bits in size long int which are going to be at least 32 bits long long int that are gonna be at least 64 unsigned int which are going to be the

same size as the signed version and long doubles which are not less in size than regular old doubles if you want to find out the number of bytes for a data type

we could come in here and get a C out and say something like size of int we could then call up size of and put my age inside of there since it is an int

and inside of C++ all statements end with a semicolon so we could just jump down here keep everything on the screen and go like that compile and execute you

can see right here size of an int is 4 bytes if I would then go in do exactly the same things for characters bullying's floats and doubles and

execute you could see how many bytes are in each one of those as well if you're wondering how big a number can be based off of bytes and so forth and so on

let's go in here and let's create the largest int that we can possibly create and whenever we know the fact how many bytes and it can contain we can then go

in and define exactly how large that number would be and you can see right here this is the biggest integer we could possibly have and if we went down

here and said hey let's go and up with that like this and you can see it prints out exactly the way that you would expect it to however if we go 1 over and

put an 8 in there instead and save that and recompile you're gonna see that you get completely different results see it comes back as a negative number that's

just a demonstration of what happens whenever you go outside of the bounds using your different data types when it comes to arithmetic you're going to be

able to use plus and minus and multiplication and division as well as modulus which is going to return the remainder of a division we're also going

to be able to use shorthand incremental notation as well as decremental give you an example of what that looks like you can see right there on your screen and

exactly how you would perform addition if you wanted output that on the screen like this and to demonstrate the shortcuts for increments and decrements

let's say that we have an int and I'm just going to get call it five and give it the value of five then I put on our screen five plus plus is equal to and

then take the variable five five and increment it I'll then increment it from the left side and then I'll decrement it from the right side and then I will

decrement it from the left side and you see what's going on right here in this situation whenever you increment from the right side it is going to actually

perform that action after it gets the current value of five that's the reason why you see five here then over here whenever you increment it on the left

side it is going to increment it first it's remember it currently has a value of six because that's what happened up here and that's the reason why you get a

seven over here and likewise whenever you have decrement on the right side it occurs after the value is taken here and then here you see that both of them are

decremented or we're back at five again we'd also be able to come in here and use another form of shorthand assignment notation by going five plus or equal to

and let's say five in this situation that right there is going to be equivalent to if you had five is equal to five plus five right like that or

let's change this into six and it's not quite so confusing and yes you could put multiple statements here on the same line just as long as you have semicolons

that's how C++ defines that a statement has ended another thing that's important is to understand order of operation in which basically it states that if you

have some calculation that's being performed the multiplication and division are going to be performed before any addition or subtraction and

you can see right here exactly what we're doing here I have braces around the additions and subtractions and up here I do not and here if I execute you

can see I get dramatically different results why is that well in this situation we are going to have the multiplication occur first that's where

you're going to get six right here then we're gonna jump in and have this add up to three which comes to negative three in this situation we're going to perform

addition and subtraction first which is going to give you a value of zero so when that's multiplied times two you're going to get zero so use braces all the

time it's gonna save you a lot of hassle now let's say we come in and we want to show some division here on our screen and this is exactly how we

do that 4/5 well if we execute that might not get the result we were looking for which into this situation comes out to zero

what happens whenever we want to actually show a floating-point number here with decimal places instead of basically just coming out to zero it's

actually very simple just come in here and we're gonna perform what is called casting to cast from any of the different data types you're gonna take

the type that you want to cast to put it between these parentheses and you can see here we now compile and execute you're gonna get exactly what you wanted

and of course these can be performed by putting int in side of here to cast to an integer even though that's exactly what it is

characters as well as doubles right like that now you can get rid of all this stuff here so that we can focus in on the if statement now the if statement is

just basically going to execute different code depending upon different conditions you're gonna have comparison operators which are going to be equal to

not equal to greater than less than greater than or equal to or less than and equal to you're also gonna have logical operators which are going to be

and or or not and they're gonna come in the form of and or or not let's go and take a look at some examples of how we could use these let's say that we create

an age which is equal to 70 years old and another age at last exam let's say we want to set up a little program here that it's going to define if a person is

going to be able to drive or not and then we have is not intoxicated and we're gonna set that to true always a good thing if you're gonna drive now

we're going to come in here with our if statements we're going to say something like if the age is greater than or equal to one and there's the logical operator

make sure you close all the brackets off the right way age is less than 16 in this situation well in that situation we're going to say that they cannot

drive now if we want to check another condition we're just going to type in else if in this situation let's check to see if they're intoxicated in this

situation we're going to use the not symbol and we're gonna say is not intoxicated and all that's going to do is take this true right here the not in

this situation and turn it in false and in that situation where to say you can't drive again I could also come in here and do an even more convoluted

thing if and it could say something like age is greater than or equal to 80 and then do another completely different comparison age is greater than 100 or

more brackets here age - age at last exam and then close that off greater than five and then close these off so what I'm basically saying here is if the

person is over the age of 100 we're not going to allow them to drive if they are going to be over the age of 80 or equal to we're basically going to require them

to take an exam every five years to verify that they are actually still able to drive it's kind of a convoluted example but I'm just trying to find a

reason to be able to come in here and show you how all these different things work and in that situation we're going to say that they can't drive and finally

where everything else that isn't checked if we want them to have the ability to drive if they make it the whole way down here we're gonna just type in else and

there you go you're gonna see that that works for you and here if we execute it you're gonna see that yes indeed this person can drive so that's a pretty

convoluted example of how to use if statements as well as else and elsif now let's take a look at switch statement which is basically going to be used

whenever you have a limited number of possible options so let's say we have int greeting option and let's say they chose two then what we're gonna be able

to do is check the versions or the values of greeting option with our switch statement put it inside of curly brackets again we're gonna say case if

the value of greeting option is equal to one well then we're going to say that we want to print out on the screen Bonjour then to jump out of the switch statement

all together we're gonna type in break and if you didn't check that it's gonna continue to check all of the other possible values like it will jump down

here if you don't have break inside and check to see if it has the value of two so you want to make sure the breaks in there have hola and all these other

different options and then finally with the switch statement if you to have a default thing that it's gonna do if none of the other things match you

just type in default and then see out and hello right like that don't need break here in this situation and you can see based off the fact that they did

enter a to hear that Jolla prints out on the screen that's basically everything you need to know about the switch statement and we'll take a look at the

ternary operator which is going to perform an assignment based off of a condition and its basic formats going to be variable is equal to there's going to

be a condition here followed by a question mark and this is the value it's going to be assigned if it is true and this is going to be the value that's

assigned if it's false and to show you a real example let's say we have integer largest num and in this situation I'm going to use real numbers we're gonna

have our condition is 5 greater than to put our question mark if it's true then we're going to assign the value of 5 to largest number and if it's false we're

going to assign the value of 2 to that number and then of course we could print that out on the screen it's that simple ternary operator now let's take a look

at arrays now arrays are just going to store multiple values of the same data type so let's come in here and provide our data type for our array just think

of a raised like boxes because that's basically what they are in memory so let's have an array here and you have to define inside of a race how many boxes

you need or how many pieces of data you want to store in them at the very beginning and then this cannot be changed

we'll look at vectors later whenever we want to look at a way to change those values could also come in here and let's say we want a array full of bad numbers

and it's also going to need 5 spaces to hold these numbers this situation we could come in here and type in all these numbers we want to store right like that

you're gonna be able to get the first item in the array with a label and the labels for all of these array items are going to start with 0 so this is gonna

have an index or label of 0 this is 1 2 3 or 4 and if we want the very first bad number in this array we're going to type in 0 just like I said and change this to

bad nums compile and execute you're gonna see the four pops up because that has the index of 0 we're also going to be able to come in here and create

multi-dimensional arrays which is just going to be boxes of boxes so let's say I wanted to have a character array that's going to be

multi-dimensional and I'm gonna have five spaces in the first array that's created here and five in the second array that's created here I could then

come in and define that I want to store the letters for my name we're gonna use two curly brackets in this situation then we're gonna close off that first

with a closing curly brace and then open it up again and here I can put my last name we jump down to the next line so it's a little bit easier to say and

we're using characters here characters always use single quotes strings is you're gonna see later on always use double quotes and then finally after we

have all those in put two curly braces in there closing and there you go that's a multi-dimensional alright if you would then want to get hold of and print out

the let's say the second letter in the second array you see out again second letter in second right we would go my name in this situation and we want to

get the second one well in that situation second is equal to 1 and then the second letter in the second array go right like that and there you can see

right there a pops up which is exactly the right one you could also come in and change the value in the array just by using its

index so we'll say my name and let's say we want to get the first array which is 0 in this situation and the second letter

inside of it or the third letter and in this situation and we want to change that to E no problem you can come in here and change this to exactly the same

place POW and execute and you can see here the new value is e just like we said it right there now I'm going to leave everything here because I'm gonna

use it while I demonstrate exactly how the for loop works now the for loop just allows you to continue executing code as long as a condition is true and you're

gonna define it with four here I'm going to give the data type for the value that I'm going to increment I'm gonna give it the initial value of one I'm gonna say

that we're gonna continue incrementing as long as I is less than or equal to ten and then we'll have to increment it right here

curly brackets and inside of the for loop we could go see out and just print all of these on our screen and there you can see it print it out one through ten

now we could also come in here and use our multi-dimensional array by stacking inner for loops and we'll just go for and

integer J is equal to zero we're gonna use zero here because arrays start off with the zero index so we're gonna say wow J is less than five we're gonna

continue to cycle through here and then inside of here we're gonna put another for loop let's have this BK is equal to zero okay is less than five increment

the value of K now we can come in here and print out my whole entire name by just putting J okay inside of there and then finally see I didn't put the end L

in there after it's done going through the for loop I could then come in here and put the character turn in and execute and there you can see it printed

out my name remember I changed the e here and then it went and printed the last name and that's what it's simply gonna do it's going to go to the first

array cycle through everything using this for loop right here let's come down here and then J is gonna come up here and it's gonna print everything out so

that's how for loops work now let's take a look at while loops now you're gonna use while loops instead of for loops when you don't know ahead of time when

your loop is gonna end so let's say we have a random number and this is how you would generate random numbers inside of C++ we go Rand and let's say that I

wanted to get random numbers between 1 and 100 modulus 100 like like that now this guy alone is going to generate random numbers between 0 and 99 so if I

want 1 to 100 I'm gonna put a 1 right here now with a while loop I can say that I want to continue cycling through this loop as long as random number is

not equal to 100 and we could print out on the screen the random number every single time and in this situation let's say we want to put a comma between there

close that off but of course you're gonna need a way to get out of this while loop so the random numbers gonna have to change so go and generate

another random number make sure we use the same thing again and then after we are done with our while loop put a character turn in there but don't forget

to put the equals sign in there and now let's go and see how long it takes us to get to 100 and there you can see it printed all those out right there on our

screen and I don't know I'm not going to count how many of those are let didn't take that long to come up with a random one hundred another thing that's kind of

interesting is you can basically simulate exactly what a for-loop does using a while loop the only thing is we're going to have to have something

that's going to increment for us this index right here will do fine and in this situation of course keep it outside of your while loop just like we did with

our random number before and we're gonna say that we want to cycle through as long as index is less than or equal to ten and then inside of your output value

of index and then of course increment your index right here and you can sing do pretty much exactly the same thing you can do with a for loop with while

loop and that brings us to do while loops and they're going to be used whenever you want to execute whatever is in the loop at the very least one time

and I'm also gonna talk about strings here for a second because we're now gonna also cover how to get user input we create a string which is just a

series of characters that's all string is int int number guests give this value of 0 start off and then the do-while loops just gonna start off with do and

then in the very end of it we're going to have the while part so you know everything is going to be executed that is in the loop at least once even if it

number guests is not equal to four so it number guests it's not equal to four and this is gonna be a basic like guessing game and you have to put a semicolon

here at the end don't forget that now inside of this we're gonna get some user input we're gonna start off by saying that the user of our program is to guess

a number between one and ten we want to allow our user to enter some input and to do that we're going to type in get line we're gonna type in c i n which is

going to be the source of the user input which is gonna be the keyboard in this situation and then we're gonna have to say where we want that value to be

stored in this situation we want to store it in the string number guests if we want to convert the string into an integer we can then go int number guests

we need to do this because this guy right here we're not going to be able to compare a string to an integer of four it's easy enough to change we're just

going to type in sto i which is going to convert a string into an integer and then we'll pass in number guest which is our string and then we could print int

number guest if we would like and this is going to continue to cycle until they enter the number four and then if they get out of our

do-while loop we could come in and go see out you win otherwise he's going to continue to ask them as you see guess between one and ten I typed in one ask

me again - now for you can see I want right so there's user input converting from strings into integers do-while and a

whole bunch of other different things let's take a deeper look at strings now in C++ in comparison to C C++ is going to provide us with string objects and

you're like I said before they are always going to be surrounded with double quotes and just to cover this real briefly inside of C you would have

previously made strings by saying something like copy array six like this is equal to and then created a character array so I'll just type it happy and

then you had to always end it with a backslash and then a zero with closing curly bracket and that's how we were using strings inside of C the C++ way is

much better and easier so we're gonna say string birthday string is equal to spacing their birthday and there we are we're done now we could of course

combine these guys and how we're going to combine them is with the concatenation operator or just a plus sign or you can just call it combined

you can call it whatever you want so birthday string and there you can see it printed happy birthday combine both of those printing them out the screen

then perform a couple other different operations let's say let's call this your name always need to define your variables before you use them and then

I'm gonna have it come in and print out the screen to get you some user input what is your name get line it's gonna get the user input get it from the

keyboard store whatever they enter into your name and then I could go see out hello put your name inside of there what's your name type in Derrick hello

Derrick talks to me cuz then come in and create let's say double in this situation we're constant you don't know what that says don't worry about it's

just a random number I thought of or Euler thought of actually I could then go string Euler guess we wanted to do like a little quiz application uppercase

letter right there just makes it easier to be able to read the variable names and then I'll go Euler guess double and now come in here ask them what is those

constants I could and get whatever they enter inside of here don't worry about it I'm gonna show you how to convert from doubles and or

from strings to doubles we need to do to convert from a string to a double and we're gonna store it and you'll learn guess double is type in instead of sto I

sto D right like that and you alert guess is the string value they entered and then I'll say if you older guess double is equal to you lure constant

which you can see all those on the screen curly brackets again see out you are right and then else you are wrong up make sure

you come in here and put an s inside of there Euler's constant Euler's constant execute what's your name Derek what's Euler's constant 0.577 21 you're right

you can see exactly how that works couple other things we can do with strings you want to get this size or the number of characters in a string see out

size of string did you use Euler guess in this situation and then just call size so it's basically exactly what you thought would be when is check if a

string is empty Euler guess again and just type in empty great to use whenever you want to test input from a user could use append also to be able to add

strings together so we could get Euler guess and call append and then add something like was your guests bounced out of there there you go

Turk point five let's type that in you were wrong didn't matter size of string is equal to three see right there decimal five five that's

the three is string empty 0 comes back or false once obviously not empty and it prints out my guests there on the screen come

in here and create another string let's call this dog string give it the value of dog and cat string give it the value of cat we can compare numbers so let's

say when you see out or compare strings them in with the comparison function and let's change this to dog and this the cat and change this the dog and you can

see in this situation whenever a value is equal like it is here dog string and dog string you're gonna get a return value of 0 you're going to receive a 1

in this situation if it's less than and a negative one if it's greater than and this is all based off of alphabetical so we could also come in here and sign

copies of a value to another store we go hole name is equal to and go your name a sign and I could say your name and there you go I could then get a

substring so let's say that I wanted to get the first name while ago hole name like that dot a sign and I would pass in the string I want to work with then the

starting index from which I want to first start pulling characters and then the number of characters I want which is five I could then come it on here change

this the first name I typed in my full name then you're gonna say that it just grabbed the substring of Derrick I could then perform a search on a string so

let's say that I wanted to find the index of my last name get the last name index if we did not know it I could type in your name and then find followed by

the substring that I want to find inside of there and the index that I want to start searching from and then I could say index for last name last name index

is my full name dr. da and you can see the index starts at six and if you count over you're gonna see that B actually is six and

also insert is going to allow me to put in a string at the index that I tell it to put it in so I'll go insert five so starting in index five I want to put in

the word Justin change this to your name just so you can see that here in a second I could also erase or delete six characters starting at the index of

seven and I'll just go your name again the string want to work with a race starting at six I want to delete six characters starting

at the seventh index and then print it out there again and then finally I could also come in and replace let's say I want to replace five characters starting

at index six well there's the index six oh I want to replace five characters and let's say that I want to change it to Maximus so my new name will be Maximus

and make sure that is name your name and here's my name you can see all the changes that are made to it right there I inserted Justin inside of there right

there I got rid of it and then right here I've performed a replace to change my last name to Maximus so there is a lot of stuff about strings okay now

let's talk about vectors now vectors are just like a race the only real difference is that their size can change and how you create

vector is type in vector and then the data type you want to store and then let's say that I'm going to store or lottery numbers in my vector then going

to decide that the initial size should be 10 I could then create an array to show you how to put an array in a vector and let's say it has a size of five and

then we'll initialize it just like we did before 14 24 and 34 like that we can then go and take our vector and insert our array and how we're gonna do that is

go lottery number effect and say that we want to start inserting at the beginning of our vector and then we'll say the array that we want to insert into it and

then let's say that we only want to take the first three numbers from our array right like that we could then go see out and just print lottery number like that

and at and let's say we want what's the third item which would be second index whoops like this you want to output that on the screen cuz remember it didn't

take the whole Ray just took these first three numbers and there you can see 14 popped up now if you would want to also come in here and let's say we want to

add another value into the fifth index lottery number dot insert we could then go lottery num vector dot begin which is the beginning of the vector plus five to

get to the fifth index and then put 44 inside of there we could then jump down here to five and see the 44 popped up push back is going to add a value at the

end of our vector so push back and let's say we want to put 64 in there we then want to defined as you can see the vector resizes we then wanted to find

that final value we can call back and it would get it for us as you can see right there pop back it's gonna remove the final value well there's no point in

doing that which in this situation would be 64 and then we could get the first value in the vector by calling front step back we could get the last element

by calling back of course empty is going to return 0 if the vector is not empty and a1 or true whenever it is empty and then finally if we wanted to get the

size of our vector we can do that with size there's a run down of all we can do with vectors now let's take a look at what we can do with functions inside a

C++ now your functions are actually going to appear before your main function and it basically just has the return type so let's say that we wanted

to have a function that added numbers we would have our return type for our function if it didn't have a return type it would have void instead of integer

and then we're going to define the data types for our attributes that are going to be received by our function second num we could also set it up so that this

function would have a default value which means actually you wouldn't have to send a second attribute in that situation the only thing that you have

to do is if you do this is all of your functions that have a default value or all of your attributes that have a default value have to come last so this

has to come before that so that's the only rule there and this is also known as a function prototype we could then go and type in combined value is equal to

first numb Plus second numb store that in there and then return the combined value and I did it this way so that I could demonstrate

something else you could take this right here and put it right down here in the return part right there you don't have to create a new variable just to perform

that another thing I want to demonstrate since I'm up here and not inside of main is that you were able to overload functions which basically means you can

use exactly the same name but different attributes so I could come in here even though I have add numbers already actually it's just copy the whole thing

paste it in there so there's add numbers twice it's okay to have add numbers the only problem is we have to have different attributes inside of here so

let's say we have second num and we also have another integer which is going to be a third num and like I said before we don't need all that we could just go

return and perform our addition right inside of here second num num and return that now let's jump down inside of main and actually call these functions if I

didn't mention before functions basically allow you to reuse code and also add a certain level of organization to your code

so here add gnomes I'm passing in one I'm gonna use the default value of zero they're not gonna pass anything and just to demonstrate it and then I'll show the

other one as well at numbers one five and six and though you can see if I execute that right there you got one and twelve popped back on the screen let's

go and create a little bit more complicated function here and this is basically what they call a recursive function and this is normally

demonstrated using the getting of factorial so that's what I'll do get factorial int number and this is gonna be a function that calls itself

from inside of itself sounds way more complicated than this so I'm gonna go and create an integer called sum then I'm gonna say if number which is gonna

be passed inside of here is equal to one then I want to have some equal to one else sum is going to be equal to get factorial C calling itself

from inside of itself and here I'm gonna go a number minus one times number this is gonna get our factorial because here we're then going to return sum so a very

quick way to get the factorial of a number and basically what is going on here is right here we'll come down to this part this is the first time through

this function and let's say number is equal to three well in that situation get factorial is called with the value of three will it actually be two let's

just focus in on this one right here so three minus one is equal to two in that situation it's going to return a value of two and then we're going to multiply

that times three so right here whenever we're going through your the second time this time we're going to be passing two into the get factorial so there we are

and two minus one is going to be equal to one and in this situation this is going to return the value of one and get factorial in this situation whenever it

comes in here the third time number is going to be equal to one so sum is gonna be equal to one and that's gonna end that functions execution and then sin as

sort of ricochet back up to the beginning so what we're going to be left with in this situation is this is gonna return one which is gonna be multiplied

times two that to right here actually goes right here and then we'll multiply that 2 times 3 which is going to give us our final

value of sex and let's go through here and let's actually run it to make sure that that's what it does and how to find out is to go factorial of 3 is and then

call the function get factorial passing the value of 3 and I'll make sure I come up here and have the return value be an integer right there and then also come

in here and remove this little parentheses I put in there by accident if we execute it you can see factorial 3 is 6 exactly like we demonstrated up

here there's a rundown of functions inside of C++ now I want to cover file i/o or how to read and write files using either text or machine readable binary

so I'm going to create a string here I'm gonna call this Steve quote it's equal to and I'm gonna say a day without sunshine is like you know night now what

I'm gonna have to do is create an output file stream to create this file if it doesn't exist or what it will do is create a function or create a file if it

doesn't exist I'm gonna call it writer and I'm going to define the name that I want to save this text into and I'm gonna call it Steve quote dot txt and

then going to verify that the file stream was created so that I'll be able to write to the file if not I'm going to put out an error message and then if we

want to signal that an error has occurred we can return a negative one in this situation else if the file stream is open that means we can write to the

file and it's very simple to write text to the file just go writer and the string you want to write and then I'll throw a new line on there at the end and

then very importantly you also want to come in and close that file stream at the end I'm going to continue going here because we got to read from it let's say

that you also wanted to come in here our file stream is closed we're gonna create another one and I'll just call this right or two and then in this situation

what we're gonna do is we're going to define that we want to write to the Steve quote text file and then here we're going to say that we want to

append what we're gonna do next to the end of what's already there now there's a whole bunch of different symbols we can here use here to do different things

with files like I just said with iOS app we're gonna be able to append to the end of the file with iOS binary we're gonna be able to treat the file as if it's

binary iOS in is going to a file to read input what you're gonna see here a minute Iowa's trunk is the default what happens whenever you don't

use one of these symbols and NIOS out is gonna open a file to write output but in this situation we're gonna be a pending and once again we're gonna need to come

in here and check that this file stream is already open and I'm just gonna copy this paste that in there make sure this is right or up here instead of right

there you go and this is gonna be right or - we're gonna spit out an error again if the file stream was not opened and then to append in this situation we're

gonna go writer and then let's say that we want to put on a new line backslash N and then a dash and then type in Steve Martin we then could come in and say

right or close and there that is alright so we wrote and we appended and we created the file and did all that now I'm gonna create a character that's

gonna hold each of the individual characters we're gonna read from our file and we're gonna read these characters using an input file stream so

input file stream and I'm gonna call this reader and you need to tell it exactly what file you're gonna be reading from and then I'm gonna check if

that stream is gonna be open just like we did before the reader inside of there come in here and print error again turn Erica negative one else we know that we

got our stream open and we'll be able to read from that file and we're gonna use a for loop in this situation to read each character from the stream until we

get to the end of the line so I'm gonna go in I is equal to zero then I'm gonna go wow the reader does not get to the end of the file we're gonna continue

reading characters and then we'll call reader get to get the next letter of output that we want and then in this situation let's just say that we want to

print that out to the screen type in letter then after the for loops all done with Yosi out and del and then once again close the reader if we did that

all right day without sunshine is like you know night so you can see it worked out and those are all the different things you can do and in regards to

reading and writing data using c++ i'm going to briefly touch on exception handling and exception handling basically allows you to avoid potential

problems in this situation i'm just going to focus on one which is a division by a zero error that could cause all kinds of problem now when

you want to cover something that could cause an exception or an error that you want to be able to catch you're gonna surround the code that could potentially

cause that air inside of what's called a try block and then what we're gonna do is when it's an if statement inside of here that says if the number is not

equal to zero well in that situation we can say C out and divide by number like we have there but as we can see that is gonna cause an error and we're never

gonna get there else we're gonna say throw number now this throw is going to look for a catch and the catch area is where we are going to catch the number

that was entered don't have to do this but it helps so that we have the error message makes sense and then we could do something like number is not violet and

then maybe you have the mask or ask them for it again you can see here if we run zero is not valid so instead of causing an error right here by putting this

inside of a try block and then throwing if they would actually enter a zero which causes potential errors we're instead gonna catch it down in this area

right here and solve it and keep our program from crashing so that's a brief explanation of exceptions okay now let's talk about pointers now when that is

stored it is stored in an appropriately sized box that is based off of its data type just like we covered previously here we have an integer and here we have

a character now like we did before we're going to be able to come in here and use sizeof to determine how many bytes that data is gonna take off and we can see

here whenever we run the program that the integer is gonna take up four bytes and the character is gonna take up one byte

now you're gonna be able to reference this box or this memory address where all of your data is stored with what is called the reference operator which is

an M purse and so we could come in here and go see out and my age is located at and then use the reference operator followed by my age and when we execute

that you can see the memory address right here now what's really cool about this is whenever we don't use pointers or we don't use reference operators and

we change a value of a variable in a regular old function that change of value does not carry on it is lost and the reason why is whenever

we use regular functions what we are in essence doing is passing a value into that function so even if we had let's say and these and we passed in some as a

variable into a function called add these just like this what's going to happen is the value of sums so let's say we have an integer here integers sum is

equal to 5 and we pass some into the add these function well if we change the value of sum and we do not pass it back sum is still going to be equal to 5

because we are passing a value with the reference operator and with pointers in general what we're gonna be able to do instead is pass by reference and any

change that is made inside of there is going to show now a pointer is going to be able to store a memory address to recreate my age to demonstrate this and

whenever you're defining a pointer you just have to use the same data type followed by a star and we'll say age pointer like this is equal to and then

you're gonna use the reference operator to pass that over just like before we're going to be able to access the memory address with this pointer of pointer by

just typing in age PTR but we'll also be able to dereference to get the data at that memory address so we'll say data at memory address and how you dereference

is to put store in front of age pointer right like that you'll see here with this pointer will now be able to get the memory address as well as the data that

is stored at that memory address let's take a look at arrays as well let's say we have our bad numbers array just like we used previously we can then go int

star to create a pointer and we'll call this number array pointer is equal to bad nums what's neat here is we're going to actually be able to increment through

our array just using shorthand notation like plus plus and minus minus so we can go see out address number array pointer and value and then to get the actual

value in the array we can go um array pointer and then close that off and then come in and go numb array pointer plus plus to get the next value

in our array I'm set in there and there you can say jumped in there grabbed four and thirteen as well as the memory addresses and as we saw previously an

integer takes up four bytes you can see the difference in the memory addresses right there you're learning about how this stuff is stored inside of here and

something else that is interesting is an array name is just a pointer to the array so we could come in and go address and put the array name by itself inside

of there at gnomes to get the value that's stored there and you can see that it works also say same memory address same value so something interesting

think about now like I said previously whenever we pass a variable to function you're passing by value however whenever you pass a pointer to a function you are

actually passing a reference that can be changed so let's jump up here and let's create a function to demonstrate exactly how this works

this isn't gonna return anything so I'm gonna pull it up void inside of there and I'm gonna say make me young and this is going to receive a pointer so I'm

gonna put int with a star after it and then age like that and then let's pull up out here on the screen the previous age I used to be like that and to get

the value of age I put a star and age because otherwise its memory address have to put that store in there but then I can also go in and change that value

by putting store and age is equal to 21 don't return anything don't have to do anything otherwise then I can come down here and call make me young and if I

want to pass a reference to that guy passing by reference that's all that means I can do that and then I could put I'm

and then just a check or verify that it actually changed that age you can do this and you can say I used to be 39 that came from the function then we

changed it to 21 inside of the function and then you can see here that it changed globally can also come in here and once again this ampersand is going

to denote that age reference will be a reference to the assigned variable so there is reference difference between a reference and a

Poynter which I'm gonna get more into when you should use one and when you should use another one I'm gonna be able to go see out you're actually going to

use references more than you use pointers like I said that's coming in a second another thing that's interesting is we could take this reference and

increment it and see that that also changed my age right like this you can see here's my age of 21 here's my age of 22

again globally we're changing all those then let's create another function this one's going to be called act your age just to pass the reference and show the

difference between passing that reference and dealing with pointers come up here and create another function it's also not gonna return anything just to

prove that nothing's exchanging hands act your age except we're passing a reference this time so we're gonna put the Empress and inside of there and I'm

just gonna put age there again doesn't matter what I put and here I'm just gonna say age is equal to 39 back down here again just demonstrating a

difference between passing by reference and passing by pointer and we could go in and prove that it's still changed age is equal to and L and there you can

see it did indeed change so basically you might ask yourself well whenever you're deciding whether you want to use pointers or references when should you

use which well basically you should use pointers if you don't want to have to initialize at declaration what that means is you can see right here I am

defining we're initializing what I'm referencing whenever I am using the reference option whenever I am dealing with pointers I do not need to

immediately initialize and then on top of that with a pointer I'm gonna be able to assign another variable to it so a pointer is gonna be able to deal with

more than one while a reference is gonna get this one reference to this one variable and be stuck with it so if you don't need to be able to change whatever

you're going to be pointing at use a reference that's pretty much the ironclad rule so and that's the basis of pointers we're gonna get more into them

here in a second but now I'm gonna jump over and talk about classes now now in object-oriented programming what we're trying to do is model real world objects

like an animal in code and how you do that is you think about well what makes a specific object an object well each object has attributes such as high

and wait and whatever and it also has capabilities so it can run and it can eat just to be really simple there well these attributes are going to be

modeled in the variables and these capabilities are going to be modeled in the functions or the methods same thing just a different name so what I'm gonna

do here inside of my class is I'm going to have some of these things be private and by private what I'm saying is that anything that is marked private

in regards to attributes or variables is only going to be able to be changed by functions inside of my class and we do that just to keep them protected and

this is called encapsulation so I'm going to have my name height and weight all be private and while I'm in here I might as well talk about static

variables basically if you put static in front of something all that means is that this variables value is going to be shared by every object of type animal

that is ever created so let's say that I want to also keep track of the number of animals that are created from my class well it wouldn't make sense that an

animal would count that's another reason why we have static here because static variables also normally are attributes that the class object would not have so

we want to be able to count the number of animals that are created but we do not want to actually have the animal type defined to be able to do it and

that brings us to public well if we have variables that are private we're going to have to have public methods that are going to be able to access the values

inside of there so we're gonna have something like get height there we go and I'm actually gonna just create this here on one line and whenever this is

called it is going to return the value that is stored for my animal object to whoever calls for it and we can also do the same thing with weight and this is

also encapsulation we're keeping all of our data protected and this is going to return a string whenever they get named functions called and we can just go

return and and there we go but what we really want to do whenever we're dealing with encapsulation is protect the values that

are going to be stored so they might want to come in here and set the height and let's say that we decide that we only want them to be able to enter a

reasonable height we could provide a check inside of here to verify that the animal height makes sense and otherwise discard it but in this situation I'll

just keep this nice and simple also going to do the exactly the same thing here for the weight so weight now let's have this be kilograms weight kilograms

and of course it doesn't matter if you put centimeters or kilograms or what you put inside of there and setname say animal name right now we have to have

this be different from this but I'm going to show you how to change that here in a second animal name right there everything else looks perfectly fine and

then we could also create another function inside of here let's call this at all and here we're creating a prototype of a function that we are

going to declare here in a second you're gonna see it and that's how we declare a prototype another thing we would want to have is a constructor and what a

constructor is first off its names gonna start with whatever the classes name is and then here we're going to create a prototype of that and this is going to

be the function that it's going to be called whenever an object is created and so it'll pass in the height the weight and the name and the constructor is

going to handle creating every object if we have a constructor we all shows should have a destructor and it just has that little tilde sign there

once again this is gonna be a prototype where I'm gonna build you don't declare the actual one down below and then let's say that we want to have another

constructor that doesn't receive anything and this is an example of overloading and to overload a function like I talked about previously the name

can be the same but the attributes need to be different so here we have two int sand a string here we are getting past nothing there's also protected members

when basically whenever we're dealing with protected what we're saying is that anything marked as protect is going to be available to members of the same

class as well as subclasses but nothing else and we could also come in here and define a static method and a static

method is set aside because they are attached to the class and to the object as you're gonna see I'm gonna show you in a second how to

actually call for a static method and in this situation static methods also can only access static member variables like this guy we have up here right there so

we are going to have this method specifically be able to return the number of animals that are created here we go and this time we're not gonna do a

prototype we'll just have it actually do what it's supposed to do there it is and also finally we'll create a two string which is going to

print out all the information we have on our animals okay so we went and we declare our class it's after this little curly bracket we're going to put a

semicolon and now we're going to declare everything so the very first thing we're gonna declare is our static number of animals and how we refer to static

variables is put the class name followed by these two colons right here and then whatever the name of it is say it's tied to the class it has absolutely nothing

to do with the object itself we can then define the prototype method first set all so set all is right here we're gonna go and define it there that was just a

prototype and we're gonna do that by putting void animal and then set all like that and then we have to define exactly what's being passed in here so

we're gonna have to inch for the height and the weight as well as the string name this basically does what the constructor does I just wanted to show

you something now if you want to refer to an object specific height and not just a generic type of height you put this inside of here and the reason we

have to do that is whenever the class is created there are no animal objects created so if we want to refer to the animals you know the specific animal

objects version or value for height we have to put this in front of it and there we go and now we can also do the same thing for weight and also name

just change this to weight and change this to weight and we could have also come up here and used this here see how we had to use centimeters instead of

having height or weight or whatever inside of there if we would have used this we would have been able to get around that just a way to refer so that

the you know the code actually knows what you're trying to code or what you're trying to do can also come in here and

change that static variable remember we are creating or changing the values here and then once again we're basically going to do this with the constructor as

well and remember the constructor is called every single time an animal object is created so there we go and it's going to be called animal going to

get to this right here int weight string name and this is basically going to do exactly the same thing that this does let's just go in there paste it in there

and you can see that basically said all does exactly the same thing that constructor does so there's no reason to put that in there I just did it just so

I could show you another function inside of there so let's just get rid of this to show you the regular functions and constructors all are the same for the D

constructor we're just gonna go animal two colons ampersand animal doesn't receive anything and we could come in here and just put a message out animal

we get the specific animal name put this in there again name and destroyed just so that we have a message on the screen to see what's going on we have our

overloaded constructor that's gonna be called whenever no attributes are passed in an animal animal it's still constructor no attributes and in this

situation we could also call that we have created another animal then we have the two string where's that uh there it is say just void two string let's come

down here and declare that void doesn't get anything animal class name two string doesn't receive attributes and here we could come in and just print out

all the information we have on our animal is and get the height for our specific animal object jump down on the next line just keep this neat

centimeters tall and this get the weight for it kilograms and weight and just close that off then we'll be able to go down in

Maine and start creating animal object so to create this let's say we want to create an animal named Fred we could then go into Fred and set his height to

thirty three set his weight to ten and set his name of course to Fred I like that just new fred animal we could then get the

values back from it i going Fred dot get name is we're not using this here just to show you the difference between trying to get the data from inside of

the class itself and then trying to get it somewhere else centimeters tall and Fred get weight kilograms in weight there we are and we

could also come in and use our constructor in this situation here we are using the default constructor that doesn't get any attributes and here

we'll use the constructor that does get attributes so we'll pass in 3615 and Tom and then we're gonna be able to also print out all the differences between

Tom and Fred let's print that out and then just change this to Tom there's Tom there's Tom there's Tom and made little error here let's just jump up to set

name and let's make sure we change this to a string and on an integer move a little bit too fast here sometimes make little mistakes and there's animal name

it's also come down here and change this name and then change this to name all right there you go now you saw that we created a Fred and a Tom object let's go

over and execute that and there you can see Fred is 33 centimeters tall 10 kilograms in weight Tom is 36 centimeters tall 15 kilograms in weight

and here you can see the destructor was called to destroy both those objects since we no longer need them now we can also come in and inherit all of the

attributes and the methods that are created from the animal object and instead use them in our dog class so there we go just news create a new dog

class and to inherit all the animal classes we just put a colon and then public and animal and that's all we need to do and we have everything that is

defined in the animal class we could come in here of course and create some new ones so let's say we wanted to have a sound string that is going to have the

value of wolf and then we could also come in and create a bunch of public methods that do some different things one thing it's going to have to do is

get the sound and in this situation I'm just gonna have that print out on our screen so sound there we go since we are going to have a sound in our dog

class and our dog objects we're going to have to declare a new constructor that's also going to get the sound so int int string and string I like that with that

prototype we could also come in here and declare a default constructor that's not going to receive anything and then on top of that called a default superclass

constructor just like going like this and there we are and we could also decide to overwrite two strings since we are also going to

be printing out the dog sound that's all we're gonna do there and then put another semicolon here at the end of course very important for our class now

we have to go in here and actually define everything that was is going to change so this is going to be the constructor for our dog and it's going

to get passed the in tight and the integer Waits and string name as well as the string mark now to reference the animal class here put a colon in animal

and we're gonna say here that we want the animal constructor to handle the height and the weight since it handled it so well previously however I want in

this constructor to be able to handle the sound part because sound doesn't exist in the animal class and here we're just gonna have it be bark so that's a

great way to have the animal constructor handle height/weight name because all those attributes are going to be shared and at the same time just change the

thing that is different saves us some space also could come in here because to string also changed so let's go in here and change it and because the attributes

like name and height and weight were private in animal I'm gonna have to use the get method to be able to access them so I'm gonna say this get name right

like that is this good height centimeters tall and this get weight kilograms in weight and says this is the thing that's different jump down here

this sound okay now I can demonstrate actually creating a dog object so let's just go dog and let's call him spot we're gonna pass

in 3816 his name is spot and the sound is going to be wolf if I also just want to demonstrate using static methods here go see out number of animals that were

created animal and to call a static method you go get numb of animals believe that's what I called it find out in a second and now I'm also gonna be

able to go spot dot get sound and we could also go in and get tom test to string which basically does with all that other stuff did up there spot dot

to string and just to show you one other thing we could also call the superclass version of a method by going animal spot animal and then putting two colons and

string and by the way I keep calling this two colons this is called the scope operator if you want to know what that's really called and of course the end here

make sure we put our return statement with zero and if we execute it you can say there is everything number of animals that were created you can see

it's three right there and that includes spot being the dog as well as Fred and also Tom so that's the reason why that showed up and the reason why is the

animal constructor was called every single time whether dog was created or animals were created you can see wolf right here is this guy right here

calling get sound you can see we're calling to string on tom to print out the information on that we can see here that spot also says wolf while the

regular animal does not not automatically works and here we're just demonstrating the use of calling to string and in this situation spot

whether he has a sound or not doesn't matter because we are calling the animal version of two string and the animal version of two string only prints out

the height and the weight as well as the name and then finally you can see right here where the destructors are called and all of our objects are destroyed

okay now it's time to talk about virtual methods and polymorphism I'm gonna hold off on the definition for polymorphism here and instead create a new animal

class and it's gonna have some public stuff that it does and what its gonna do here first off is get family which I'm going to refer to as a family

objects and there's just say we are animals close that off and then this is where we get to virtual methods I'm gonna mark this as virtual and then I'm

gonna change it back from virtual basically we mark a method as virtual when we know that an animal in this situation will be a base class that may

have this method overwritten by a subclass and you're gonna see it in action here it'll make more sense when you see it in action so in this

situation let's say get class and then I'm gonna go I'm and animal ok so these are all in the family of animals but the specific class for this is animal in

this situation and close that off and now we're gonna need to create a subclass called dog of type and more it's going to inherit from animal and

it's going to have public course it inherits everything get class in this case I'm a dog is gonna get printed out and then close off that class now what

we're gonna be able to do here is come down inside of here create an animal class is equal to new animal and dog in this situation new dog now in this

situation it's not going to matter if this is marked as virtual or not because these are both references to animals and dogs as you can see right here I can

just go animal - get class and dog dot get class right like that here I got the virtual part off of there and here you can see if I execute this I'm a dog and

I'm an animal both print there on the screen if I was however going to try and call get class from a function you're going to see that we get some problems

so here we're gonna say void what class are you and we pass in an animal object they're both animal objects remember well you would think I'd be able to go

animal get class and get exactly the same results however as you're going to say if I do that by passing in animal and dog we don't get the results we

expect instead what happens is I'm an animal gets passed in both times if we want to be able to call the proper get class for the dog and the proper get

class for the animal all we need to do is come up here and type in virtual and all that means is it's saying hey we expect this to change so if you get a

dog whether it's an animal or not why don't you go take a chance and take a look at if getclass resides in the dog class or dog object and they're gonna

say everything prints out exactly the right way now we're gonna come up and create a couple more classes let's say that we also want to create another

class and let's call this German Shepherd which is a little bit more specific and it is going to be of type dog and then we'll go in and type in

public void and overwrite get class with I'm a German Shepherd ndele closing curly bracket and void get derived I'm an animal and dog endo

closing curly bracket and now come down here and experiment a little bit more see basically polymorphism all it means is whenever a animal is passed in in

this situation like it did right here we passed in an animal object it's automatically going to find the right method to call so that's that's

basically it now there's many ways you can apply polymorphism but polymorphism on its own looks like that so let's create a dog object and let's create a

German Shepherd and call him max the base class can also call derived class methods as long as they exist in the base class so we're gonna come up here

create an animal it's a pointer to the dog and to get a reference to spot we just put that little Empress and in there create another one and point this

to the german shepherd get a reference to that with max we can now call the method that was not overwritten by any of the other classes get family that's

the same an animal we could also call get class which was overwritten and then come in here change this to void sorry about that and then of course also close

off our class the curly bracket and execute it and there you can see we are dogs we were able to call this guy properly and then I'm a dog see this is

a reference to dogs spot and we were able to call the proper get family because this was listed as an animal and also we were able to call the

a specific class that resides in dog even though these were listed as animals another example of polymorphism another thing that's neat is we can actually

call the superclass or a German Shepherd because everything is inherited so we can call get family that resides in the animal class and of course we can also

call the overwritten German Shepherd version from Shepherd and it's automatically going to go and get the right thing as you can see right there

we are animals and I'm a German Shepherd so there's an example of using virtual methods as well as a whole bunch of different examples on how polymorphism

works and then to finally get polymorphism 100 percent in your head let's go and create an animal object as well as a dog object and a cat object

that all inherit from the animal class now the animal is going to be a virtual method again because we're going to override it and we're gonna treat them

as animals because they are curly bracket and we'll say the animal says ger basically gonna do exactly make sure you put that closing curly bracket on

there and then we're not gonna copy the virtual part in this situation in the dog here we're gonna say the dog says wolf and the cat says meow as homework

you could look into how you would actually set up an animal class as a capability class that exists only to be derived from so look into that that is

your homework because you guys asked for homework all the time and now I'm gonna also jump in here and give you an example of what an abstract data type

looks like so let's say we have a car and this is more for completionists reasons than anything else we could come in here and public again virtual int get

numb wheels the value is zero and virtual int get numb doors and then you'd be able to derive this by coming in here and creating a new class called

stationwagon inherit from car even though car doesn't do anything closing bracket move that up and then come in and define everything that we saw in the

generic car or the generic car abstract data type get numb wheels as for wheels like that close that off and then we could go int get numb doors

just like we defined I'll pair in this abstract data type for car stationwagon has four doors and then we could also come in here and go stationwagon

create an empty constructor and a destructor right like that now let's jump down in main and play around with these guys so we're gonna create another

animal here for our cat and to do that we just call cat and animal dog new dog and we can see that if we call the cat specifically saying we want it to make a

sound and then we do the same thing with the dog you can see that the cat says meow and the dog says woof even though they're both set off as animals now

let's go in and test our abstract data type with the car let's create a stationwagon of type car it's equal to the new

station wagon like this and even though is a car object it Nam wheels you can see that station wagon has four wheels shows up there on the screen

there's a whole bunch of different examples of polymorphism and a whole lot of information on C++ hope you guys enjoyed this video if you actually watch

the whole entire thing please leave a comment telling me so I would really appreciate that and please leave your questions and

comments below otherwise till next time