Structures CS50 English Basque

StructuresYouTube↗ IA↗(long shot)
Education 26.4K views 123 likes 1 dislikes 07 Oct 2015

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>> [MUSIC PLAYING]

>> [Musika jotzen]

>> DOUG LLOYD: OK.

>> DOUG LLOYD: OK.

We've worked with integers, we've worked with characters,

Osoko zenbaki lan egin dugu, Pertsonaien lan egin dugu,

we've worked floats, doubles, strings, and bools.

Nik egin dugu lan karroza, bikoitzak, kateak, eta bools.

We've exhausted pretty much all of the [INAUDIBLE] types that

Nahiko agortu ditugu askoz guztiak [INAUDIBLE] mota duten

have been available to us all along.

izan dira gu guztion eskura batera.

But now we want to do something more.

Baina orain zerbait gehiago egin nahi dugu.

How do we do that?

Nola egiten dugu?

How do we create different data types?

Zelan datu-mota ezberdinak sortzen dugu?

We can do so by using structures.

Horrela egin ahal izango ditugu, egiturak erabiliz.

So structures allow us to unify variables of different types

Beraz egiturak behar bateratzeko gurekin baimendu Mota desberdinetako aldagaiak

into a single, new variable type, which we can assign its own type name.

motako aldagai bakar batean, zein bere motaren izen propioa ezarri ahal izango dugu.

This is a really strong thing to be able to do,

Hau da, benetan sendoa gauza egin ahal izateko,

because we can now group elements of different data types

orain ezin dugu talde delako Datu mota desberdinetako elementu

together that have a logical connection.

elkarrekin duen konexio logikoa dute.

We've been able to do this with arrays sort of, right?

Hau egin ahal izan dugu arrayak Sort batera, ezta?

We can group variables of the same data type

Ahal dugun aldagai-taldea datu-mota bereko

together in a large unit of memory, an array.

elkarrekin unitate handi batean memoria, array baten.

>> But we haven't been able to mix up different data types together.

>> Baina ez dugu nahastu ahal izan Datu mota desberdinak elkarrekin.

We can't, say, pair an integer, and a character, and a double all

Ezin, esan dugu, parekatu zenbaki oso bat, eta pertsonaia bat, eta bikoitza guztiak

in the same thing and call that a single unit.

Gauza bera, eta, deitu dute batasun bat dela.

But with structures, or frequently referred to as structs,

Baina egitura, edo Maiz structs gisa aipatzen,

we actually can.

Benetan ahal izango dugu.

So a structure is sort of like a super variable.

Beraz, egitura bat da, ordenatu super aldagai bat bezala.

It's a variable that contains other variables inside of it.

Egin dituen aldagai bat Beste aldagai horren barruan.

So here's an example of a very simple structure.

Hortaz, hona hemen adibide bat egitura oso erraza da.

This is what the syntax would look like to create a structure for a car.

Hau da, sintaxia zer bilatzen ari antzeko egitura bat sortzeko auto bat da.

Now, let's go through the syntax here.

Orain, goazen sintaxia barrena.

Struct, that's the keyword that indicates

Egiturari, hori da Hori dela adierazten keyword

that I'm creating a new data type here.

datu-mota berri bat sortzen ari naiz hemen.

In particular, the data type's name is going to be struct car, as we'll see.

Hain zuzen ere, datu-mota baten izena da Eta egitura autoa izango da, ikusiko dugun bezala.

But this is the sort of tip off to the compiler that this

Baina honek punta sailkatu da konpilatzailea off hori

as a group of variables that is going to be considered part of the same type

aldagai-multzo bat bezala hori joan Mota bereko parte hartu behar dira kontuan

>> Cars, just the name of the structure.

>> Autoak, besterik egitura baten izena.

Again, the data type here is going to be struct car, not just car.

Berriz ere, datu-mota hemen va Eta egitura autoa, ez bakarrik autoa izateko.

But if you have different-- if you create multiple structs

Baina desberdina izan beharko duzu Anitz structs sortzen baduzu

in the same program, you need to distinguish between struct and struct.

programa berean, behar duzun Eta egitura eta egiturari artean bereiztea.

So struct car, I might also have struct student, for example,

Beraz, eta egitura autoa, agian dut, gainera, egitura ikaslea, adibidez,

in the same program.

programa berean.

Inside of the curly braces are all of the so-called fields,

Kizkur giltza Inside dira deiturikoak eremu guztiak,

or members of the structure.

edo egiturako kide.

So what are some of the things that are inherent in a car?

Beraz, zer dira gauza batzuk direla auto batek berezko?

Well, it usually has a year, has a model name, and a license plate,

Beno, normalean urte bat du, ha eredu baten izena, eta matrikula bat,

an odometer that usually has some number of miles on it,

distantzia bat izan ohi ditu mila gainean kopuru batzuk,

and maybe an engine size.

eta, agian, motorraren tamaina bat.

And as you can see, I'm mixing up integers and characters and doubles.

Eta ikusiko duzunez, nahasten ari naiz Osoko zenbaki eta pertsonaiak eta bikoitzak.

They're all going to be part of this new data type.

Ari dira guztiak ere izango da joan datu-mota berri honen zati.

>> Lastly, the final thing I need to do, don't forget this little semicolon

>> Azkenik, final gauza egin behar dut, ez ahaztu semicolon txiki honetan

After we finish defining the structure, we need to put a semicolon at the end.

Egitura definitzeko bukatu ondoren, puntu eta koma bat jarri amaieran behar dugu.

It's a very common syntactical mistake, because with a function,

Sintaktikoak oso ohikoa da Akats, funtzio bat delako,

for example, you would just have open curly brace, close curly brace.

adibidez, besterik ez litzateke izango duzu kizkur irekia, itxi kizkur.

You don't put a semicolon at the end of a function definition.

Zuk ez duzu jarri puntu eta koma at funtzioaren definizio baten amaieran.

This looks like a function definition, but it's not,

Hau funtzio baten itxura definition, baina ez da,

and so the semicolon there is just a reminder that you

eta, beraz, puntu eta koma ez oroigarri bat besterik ez da egin behar duzu

need to put it there, because the compiler will otherwise not

han jarri behar, zeren konpilatzailea izango Besterik ez

know what to do with it.

dakit zer egin.

It's a very common error to accidentally make

Error oso ohikoa da ustekabean egin

when you're first defining structures.

aurreneko egiturak definitzeko zaren.

So we usually define our structures at the very top of our programs

Beraz, gure egiturak definitu dugu gure programak hasieran zenbait

because they're probably going to be used by multiple functions.

seguruenik ari dira joan delako funtzio askotara erabiltzeko.

We don't want to define a struct inside of a function,

Ez dugu bat zehaztu nahi funtzio baten barruan, eta egitura,

because then we can only-- the scope of the structure really

orduan sor baitezakete daitekeelako dugu egitura esparrua benetan

only exists inside of that function.

bakarrik funtzio horren barruan lehendik.

We'd probably want to define a structure so we can use it in multiple functions,

Seguruenik litzaidake egitura bat definitu nahi dugu beraz, erabili ahal izango dugu, funtzio bat baino gehiago ere,

or perhaps in multiple files that are tied together

edo agian bat baino gehiago elkarrekin lotuta daude fitxategiak

to create our single program.

Gure programa bakar bat sortzeko.

Sometimes also instead of defining the structure

Batzuetan, gainera, ordez egitura definitzeko

at the very top where you put your pound includes and your pound defines,

Oso goian non jarri duzu zure etxean libra sartutakoak zure kiloko definitzen,

for example, you might put them in separate dot h files, which you then

adibidez, jartzea baliteke ere Aparteko dot h fitxategiak, eta gero

pound include yourself.

libra artean, zeure burua.

>> So we have structures, but now we need to get inside of them.

>> Beraz, egiturak izan dugu, baina, gaur egun, horietako barruan lortu behar dugu.

How do we get inside of a structure to access

Zelan barruan lortu dugun sarbide egitura

those sub-variables, those variables that exist inside the structure?

horiek azpi-aldagai, aldagai horiek egituraren barruan existitzen dela?

Well, we have something called the dot operator, which allows us

Beno, izeneko zerbait egin behar dugu dot operadorea, eta horrek aukera ematen digu

to access the fields of the structure.

egitura arloetan sartzeko.

So for example, let's say I've declared my structure data type somewhere

Beraz, adibidez, demagun deklaratu dut Nire egitura datuak idatzi nonbait

at the top of my program, or perhaps in a dot h file that I've pound included.

Nire programa goialdean, edo, agian, sartzen dot h fitxategi hori dizkiat kiloko.

If I then want to create a new variable of that data type, I can say,

Orduz berri bat sortu nahi dut Datu mota horretako aldagai, esan dezaket,

struct car, my car, semicolon.

Eta egitura autoa, nire autoa, koma.

Just like I could say int x, or string name semicolon.

Just like int esan izan dut x, edo kate izena koma.

>> The data type here is struct car, the name of the variable is my car,

>> Datu-mota hemen struct autoa da, aldagaiaren izena, nire autoa da,

and then I can use the dot operator to access the various fields of my car.

eta ondoren dot operadorea erabili ahal izango dut Nire autoa hainbat arlotan sartzeko.

So I can say my car dot year equals 2011.

Beraz, nire auto esan dezaket dot urteko berdinen 2011.

That's perfectly fine.

Hori da, guztiz fina.

Year, if you recall, was defined as an integer field inside of this struct car

Urtea, gogoratzen baduzue, zen bezala definitu Eta egitura auto honen barruan zenbaki oso eremu

So any variable of the struct car data type, such as my car, I can say my car

Beraz, eta egitura auto datuen aldakorra duen mota, hala nola, nire autoa bezala, nire auto esan dezaket

dot year equals and then assign it some integer value, 2011.

dot urteko berdinen eta ondoren esleitu zenbaki oso balio batzuk, 2011.

My car dot plate equals CS50.

Nire autoa dot plaka berdinen CS50.

My card dot odometer equals 50505 semicolon.

Nire txartela dot distantzia 50505 semicolon berdin.

All of those are perfectly fine and that's

Horiek guztiak ez dira guztiz fina eta hori da

how we access the fields of the structure.

nola sartzeko dugu egitura arloetan.

Structures, though, do not need to be created on the stack.

Egiturak, ordea, ez da beharrezkoa pilan sortuko.

Just like any other variable, we can dynamically allocate them.

Bezalakoa, aldakorra, dugu dinamikoki esleitu ahal izango die.

If we have a program that might be generating many structures,

Programa bat izaten badugu agian den egitura asko sortuz,

we don't know how many we're going to need,

ez dakigu zenbat behar dugu,

then we need to dynamically allocate those structures

Orduz dinamikoki behar dugu egitura horiek esleitu

as our program is running.

Gure programa bezala exekutatzen da.

And so if we're going to access the fields of a structure in that context,

Eta hala bada gabiltza sartzeko joan Testuinguru horretan egitura baten eremuak,

recall that we first need to dereference the pointer to the structure,

gogoratzen dugun lehen erreferentzia kenduta behar egitura erakuslea,

and then once we dereference the pointer, then we can access the fields.

eta gero guk dereference behin erakuslea, gero eremu horretan sartzeko aukera izango dugu.

If we only have a pointer to the structure,

Izanez a dugu egitura erakuslea,

we can't just say pointer dot field name and get what we're looking for.

Ezin dugu besterik gabe, esan erakuslea dot eremu izendatzeko eta zer bilatzen ari gara.

There's the extra step of dereferencing.

Ez dago aparteko dereferencing urratsa da.

So let's say that instead of the previous--

Beraz, demagun ordez previous-- du

just like the previous example, instead of declaring it

besterik gabe, aurreko adibide bezala, ordez geratuko

on the stack, struct car, my car, semicolon, I say struct car,

pila, egiturari autoa, nire autoa, puntu eta koma, eta egitura auto esan dut,

star, a pointer to a struct car called my car,

izarra, erakuslea Eta egitura auto nire autoa deitzen,

equals malloc size of struct car.

Eta egitura auto tamaina malloc berdin.

Size of we'll figure out how many bytes your new data type takes up.

Dugu neurria irudikatu zenbat byte zure datu-mota berri hartzen.

You don't necessarily only need to use size of, width, int, or char, or any

Ez duzu zertan bakarrik erabili behar ren, zabalera, int edo char, edo edozein tamaina

of the built-in data types.

eraiki-datu motak.

The compiler is smart enough to figure out how many bytes

Konpilatzailea smart nahikoa da Irudikatu nahi byte zenbat

are required by your new structure.

Zure egitura berriak eskatzen dituzte.

So I malloc myself a unit of memory big enough to hold a struct car,

Beraz, neure burua malloc I memoria unitate bat big nahikoa struct auto bat eduki,

and I get a pointer back to that block of memory,

eta erakuslea lortu dut atzera oroimenaren bloke hori,

and that pointer is assigned to my car.

eta erakuslea da nire autoa esleitzen.

>> Now, if I want to access the fields of my car,

>> Orain, bada sarbidea nahi dut Nire autoa arloetan,

I first dereference my car using the dereference operator, star

Lehenengo nire autoa dereference erabiliz I dereference operadorea, izarraren

that we've seen from the pointers videos, and then after I dereference,

Nik dugun erakusle ikusita bideoak, eta orduan ez dereference ondoren,

then I can use the dot operator to access the various fields of my car.

Orduz dot operadorea erabili ahal izango dut Nire autoa hainbat arlotan sartzeko.

Star my car dot year equals 2011.

Star Nire autoa dot urteko berdinen 2011.

That would have the effect we want in this case,

Eragina izango luke Kasu honetan, nahi dugu,

because we've dynamically allocated my car.

dinamikoki dut dugulako Nire autoa esleitu.

>> That's kind of annoying, though, right?

>> Hori da mota gogaikarriak, ordea, ezta?

There's a 2-step process now.

Badira 2-prozesuan urrats bat da gaur egun.

Now we have to dereference-- we have a star operator,

Orain dereference-- daukagu izar operadorea bat dugu,

and we have a dot operator.

eta puntu operadorea bat behar dugu.

And as you might expect, because C programmers love shorter ways

Eta espero dezakezun bezala, zeren C programatzaileak maite modutan laburragoa

to do things, there is a shorter way to do this.

gauzak egin ahal izateko, ez da bat bide laburragoa hori egin ahal izateko.

There is another operator called arrow, which makes this process a lot easier.

Ez dago gezi izeneko beste operadore da, Horri esker, prozesu honetan asko errazagoa.

The way arrow works is it first dereferences

Modu gezi lan egiten da Lehenengo Dereferences da

the pointer on the left side of the operator,

ezkerreko erakuslea operadoreak alde,

and then, after having dereferenced the pointer on the left,

eta, ondoren, dereferenced ondoren ezkerreko erakuslea,

it accesses the field on the right.

eskuin hegaletik eremu sartzen da.

And so previously we had this sort of star my car dot all this stuff,

Eta, beraz, aldez aurretik moduko hau izan genuen izar nire autoa guzti hau dot,

like there was a lot going on there.

atsegin han asko han izan zen.

But what we can instead do is this-- my car arrow year equals 2011.

Baina zer dugun ordez egin ahal izango da hau Nire autoa gezi urteko berdinen 2011.

>> Again, what's happening here?

>> Berriz ere, zer gertatzen da hemen?

First, I'm dereferencing my car.

Lehenik eta behin, nire autoa dereferencing naiz.

Which again, is a pointer here.

Zein berriz, erakusle bat da hemen.

Then, after having dereferenced my car, I

Gero, ondoren Nire autoa dereferenced, I

can then access the fields year, plate, and odometer

ondoren, eremu horretan sartzeko dezake Urte, plaka, eta distantzia

just as I could before having first used star to dereference my car,

nuen bezala, aurreneko aurretik Nire autoa dereference izarra,

and dot to access the field.

eta sakabanatutako eremuan sartzeko.

So you can have structures, you can have pointers to structures,

Beraz, egiturak izan dezakezu, zuk erakusle izan daiteke egituretan,

and you have ways to access the fields of those structures,

eta sarbide moduak duzu egitura horiek arloetan,

whether you have pointers to them or the variables themselves.

erakusleak egin behar duzun ala ez Horietako edo aldagai beraiek.

Dot or arrow, depending on how the variable was declared.

Dot edo gezi, arabera aldakorreko nola izendatu zuten.

I'm Doug Lloyd, this is CS50.

Naiz Doug Lloyd, hau CS50 da.

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