Working with an Array Udacity English English (auto-generated)

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all right so I think we have a better

So I think we have a better idea now of when we should and

idea now of when we should and should

should not use arrays.

not use a raise

>> Yeah. But we haven't talked about how to

yeah but we haven't talked about how to

use arrays in code.

use a raise in code like do each of

Like do each of these thoughts have a variable name?

these thoughts have a variable name well

>> Well not exactly.

So the entire array itself has a single name.

slowly entire rate itself has a single

So, for example, we can call this array something like words.

name so for example we can call this array something like words okay so the

>> Okay. So the whole array is called words.

whole array is called words but how do I

But how do I get access to the string in each slot.

get access to the string in each side

>> Well each slot is called an element of the array and we can access each

well each slot is called an element of the array and we can access each element

element by referring to its numerical position or index in the array.

by referring to its a numerical position or index in the array weight index

>> Wait, index? >> Yeah, so each position is numbered, It's kind of weird but

yeah so each position is numbered and

we start with the next zero and then move up to next one, two and so

it's kind of weird but we start with the index 0 and then move up to index 1 2

on until we reach the end of the array.

and so on until we reach the end of the

>> Okay, so for an array of length seven we start at index zero and

array okay so for an array of length 7 we start at index 0 and we end at index

we end at index six. >> Yeah, precisely.

6 precisely and all these numbers

And all these numbers together are called indices.

together are called indices because a

>> Because the plural word for index is indices.

plural word for indexes indices okay so

Okay so it makes sense.

it makes sense now my question is how do

Now my question is how do we put values into the array in the first place?

we put values into the array in the

>> Well, similar thing.

first place well similar thing so we

So we refer to a specific index of the array by using the equal sign

refer to a specific index of the array by using the equal sign which remember

which remember is the Simon operator and we assign the value into that position.

is the címon operator and we assign the value into that position

>> Wait I think I need to see this written down can I look at

wait I think I need to see this written

the code for this?

down can you look at the code for this

>> Yeah for sure. Anything for you, Kay.

yeah for sure anything for you okay I'm

I'm going to walk you through some code samples now and

gonna walk you through some code samples

I don't want to give away the solution for the me walk up.

now and I don't want to give away the solution for the Miwok app so I'm gonna

So I'm going to be using a different example.

be using a different example so say we

So say we have an app where users can buy shoes online and

have an app where users can buy shoes

our app needs to keep track of which types of shoes are still in stock.

online and our app needs to keep track of which types of shoes are still in

So one particular type of shoe is really popular but

stock so one particular type of shoe is

we only have three sizes left.

really popular but we only have three

How should we store that information?

sizes left how should we store that

Well since this is all related information about the same

information well since this is all related information about the same pair

of shoes we should keep them in our

We should keep them in an array.

Later, this makes it easier to figure out which sizes are available

later this makes it easier to figure out which sizes are available because we can

because we can refer to the single array variable

refer to this single array variable

instead of checking a bunch of separate variables.

instead of checking a bunch of separate

So first we start off by creating the array.

variables so first we start off by

Since there are three sizes left, we'll create an integer array of length three.

creating the array since there are three sizes left we'll create an integer array of length three each element of the

Each element of the array will be one shoe size that is available and

array will be one shoe size that is

the shoe size is an integer.

available and the shoe size is an

I know the syntax can be a little tricky, it may look a little

integer I know the syntax can be a little tricky I may look a little

overwhelming because there's brackets and spaces all in weird places but

overwhelming because there's brackets and spaces all in weird places but

creating this array variable is similar to how we've created integer and

creating this array variable is similar to how we've created integer and

string variables in the past.

string variables in the past on the left

On the left here, we have the data type.

here we have the data type which in this

Which in this case is an integer array.

case is an integer array it's the name

It's the name of the data type which is the word int, followed by the open and

of the data type which is the word int followed by the open and close bracket

close bracket. Then, we have the name of the array variable,

then we have the name of the array

which is shoe sizes available, followed by an equal sign then the new cue word

variable which is shoe sizes available followed by an equal sign then the new

followed by the data type of the array again.

keyword followed by the data type of the

Int, with the open and close brackets again.

array again int with open and closed

But this time, notice that we put the length of the array inside the bracket.

brackets again but this time notice that we put the length of the array inside

Now we have an empty array of length three.

the bracket now we have an empty array

So if you ever wanted to change the type of data in this array,

of length three so if you ever wanted to change the type of data in this array

such as having it store Booleans to be a Boolean array,

such as having it store boolean to be a

then you would put Boolean here and here.

boolean array then you would put boolean here and here now we can assign values

Now we can assign values to each element of the array

to each element of the array based on

based on the index position.

the index position for the given array

For the given array, the recalling shoe sizes available here.

that we're calling shoe sizes available

We use the open and close brackets with the index number in the middle.

here we use the open and closed brackets with the index number in the middle

Example we've, and in this first example, we've assigned the number

example we've and in this first example we've assigned the number five into the

5 into the index 0 slot of the array by using the equal sign and so

index 0 slot of the array by using the

in this case the equal sign is the assignment operator.

equal sign and so in this case this equal sign is the assignment operator

Notice that there is no space between the name of the array and the brackets.

notice that there's no space between the name of the array in the brackets so

So when these three statements have been executed the array looks like this.

when these three statements have been executed the array looks like this later

Later if you need to retrieve or access elements of the array use the name of

if you need to retrieve or access elements of the array use the name of

the array variable followed by the brackets and index in the middle.

the array variable followed by the brackets and index in the middle so this

So this line of code here, will retrieve the first element of the array.

line of code here will retrieve the first element of the array and the

And the result of this call, is 5.

result of this call is 5 remember that

Remember that indices start at 0 and increment consecutively. So this is index zero, one and two.

the indices start at 0 and increment consecutively so this is index 0 1 and 2

And similarly the result of the next line of code is 7 and

and similarly the result of the next line of code is 7 and the following one

the following one is 10. If you need to get the size of the array

is 10 if you need to get the size of the

write out the name of the array variable and then call .length.

array write out the name of the array variable and then call dot length in

In this case this expression yields the number three for

this case this expression yields the

the three slots in the array.

number 3 for the three slots in there

So here's some practice on how to use an array.

rain so here's some practice on how to

There are many real world things that can be represented as an array.

use an array there are many real-world things that can be represented as an

For example, think of a soccer team with 11 players,

array for example think of a soccer team

where each member has a different jersey number.

with 11 players where each member has a different jersey number we want to

We want to assign the number of their soccer jerseys at each

assign the number of their soccer

place in this integer array.

jerseys at each place in this integer

Assume we've chosen four players for the roster already.

array assume we've chosen four players for the roster already we can store

We can store the jersey numbers of these four players at

the jersey numbers of these four players

four different array indices.

at four different array indices so for

So for the purpose of this exercise.

the purpose of this exercise we'll put

We'll put the jersey numbers in random spots of the array.

the jersey numbers in random spots of

Look at the different options of code in the provided gist and

the array look at the different options of code in the provided gist and pick

pick the option that contains the code that would create the array above.

the option that contains the code that would create the array above

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