Zašto koristiti strukturu?

U C-u postoje slučajevi kada moramo pohraniti više atributa entiteta. Nije nužno da entitet ima sve informacije samo jedne vrste. Može imati različite atribute različitih vrsta podataka. Na primjer, entitet Student može imati svoje ime (string), broj role (int), oznake (float). Za pohranjivanje takve vrste informacija o entitetskom studentu, imamo sljedeće pristupe:

• Konstruirajte pojedinačne nizove za pohranjivanje imena, brojeva rola i oznaka.
• Koristite posebnu strukturu podataka za pohranjivanje zbirke različitih tipova podataka.

Pogledajmo detaljnije prvi pristup.

 #include void main () { char names[2][10],dummy; // 2-dimensioanal character array names is used to store the names of the students int roll_numbers[2],i; float marks[2]; for (i=0;i<3;i++) { printf('enter the name, roll number, and marks of student %d',i+1); scanf('%s %d %f',&names[i],&roll_numbers[i],&marks[i]); scanf('%c',&dummy); enter will be stored into dummy character at each iteration } printf('printing details ...
'); for (i="0;i&lt;3;i++)" printf('%s %f
',names[i],roll_numbers[i],marks[i]); < pre> <p> <strong>Output</strong> </p> <pre> Enter the name, roll number, and marks of the student 1Arun 90 91 Enter the name, roll number, and marks of the student 2Varun 91 56 Enter the name, roll number, and marks of the student 3Sham 89 69 Printing the Student details... Arun 90 91.000000 Varun 91 56.000000 Sham 89 69.000000 </pre> <p>The above program may fulfill our requirement of storing the information of an entity student. However, the program is very complex, and the complexity increase with the amount of the input. The elements of each of the array are stored contiguously, but all the arrays may not be stored contiguously in the memory. C provides you with an additional and simpler approach where you can use a special data structure, i.e., structure, in which, you can group all the information of different data type regarding an entity.</p> <h2>What is Structure</h2> <p>Structure in c is a user-defined data type that enables us to store the collection of different data types. Each element of a structure is called a member. Structures ca; simulate the use of classes and templates as it can store various information </p> <p>The <strong>,struct</strong> keyword is used to define the structure. Let&apos;s see the syntax to define the structure in c.</p> <pre> struct structure_name { data_type member1; data_type member2; . . data_type memeberN; }; </pre> <p>Let&apos;s see the example to define a structure for an entity employee in c.</p> <pre> struct employee { int id; char name[20]; float salary; }; </pre> <p>The following image shows the memory allocation of the structure employee that is defined in the above example.</p> <img src="//techcodeview.com/img/c-tutorial/01/c-structure.webp" alt="c structure memory allocation"> <p>Here, <strong>struct</strong> is the keyword; <strong>employee</strong> is the name of the structure; <strong>id</strong> , <strong>name</strong> , and <strong>salary</strong> are the members or fields of the structure. Let&apos;s understand it by the diagram given below:</p> <img src="//techcodeview.com/img/c-tutorial/01/c-structure-2.webp" alt="c structure"> <h2>Declaring structure variable</h2> <p>We can declare a variable for the structure so that we can access the member of the structure easily. There are two ways to declare structure variable:</p> <ol class="points"> <li>By struct keyword within main() function</li> <li>By declaring a variable at the time of defining the structure.</li> </ol> <p> <strong>1st way:</strong> </p> <p>Let&apos;s see the example to declare the structure variable by struct keyword. It should be declared within the main function.</p> <pre> struct employee { int id; char name[50]; float salary; }; </pre> <p>Now write given code inside the main() function.</p> <pre> struct employee e1, e2; </pre> <p>The variables e1 and e2 can be used to access the values stored in the structure. Here, e1 and e2 can be treated in the same way as the objects in <a href="/c-tutorial">C++</a> and <a href="/java-tutorial">Java</a> .</p> <p> <strong>2nd way:</strong> </p> <p>Let&apos;s see another way to declare variable at the time of defining the structure.</p> <pre> struct employee { int id; char name[50]; float salary; }e1,e2; </pre> <h3>Which approach is good</h3> <p>If number of variables are not fixed, use the 1st approach. It provides you the flexibility to declare the structure variable many times.</p> <p>If no. of variables are fixed, use 2nd approach. It saves your code to declare a variable in main() function.</p> <h2>Accessing members of the structure</h2> <p>There are two ways to access structure members:</p> <ol class="points"> <li>By . (member or dot operator)</li> <li>By -&gt; (structure pointer operator)</li> </ol> <p>Let&apos;s see the code to access the <em>id</em> member of <em>p1</em> variable by. (member) operator.</p> <pre> p1.id </pre> <h3>C Structure example</h3> <p>Let&apos;s see a simple example of structure in C language.</p> <pre> #include #include struct employee { int id; char name[50]; }e1; //declaring e1 variable for structure int main( ) { //store first employee information e1.id=101; strcpy(e1.name, &apos;Sonoo Jaiswal&apos;);//copying string into char array //printing first employee information printf( &apos;employee 1 id : %d
&apos;, e1.id); printf( &apos;employee 1 name : %s
&apos;, e1.name); return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> employee 1 id : 101 employee 1 name : Sonoo Jaiswal </pre> <p>Let&apos;s see another example of the structure in <a href="/c-programming-language-tutorial">C language</a> to store many employees information.</p> <pre> #include #include struct employee { int id; char name[50]; float salary; }e1,e2; //declaring e1 and e2 variables for structure int main( ) { //store first employee information e1.id=101; strcpy(e1.name, &apos;Sonoo Jaiswal&apos;);//copying string into char array e1.salary=56000; //store second employee information e2.id=102; strcpy(e2.name, &apos;James Bond&apos;); e2.salary=126000; //printing first employee information printf( &apos;employee 1 id : %d
&apos;, e1.id); printf( &apos;employee 1 name : %s
&apos;, e1.name); printf( &apos;employee 1 salary : %f
&apos;, e1.salary); //printing second employee information printf( &apos;employee 2 id : %d
&apos;, e2.id); printf( &apos;employee 2 name : %s
&apos;, e2.name); printf( &apos;employee 2 salary : %f
&apos;, e2.salary); return 0; } </pre> <p> <strong>Output:</strong> </p> <pre> employee 1 id : 101 employee 1 name : Sonoo Jaiswal employee 1 salary : 56000.000000 employee 2 id : 102 employee 2 name : James Bond employee 2 salary : 126000.000000 </pre> <hr></3;i++)>

Gornji program može ispuniti naše zahtjeve za pohranjivanje podataka entitetskog studenta. Međutim, program je vrlo složen, a složenost se povećava s količinom unosa. Elementi svakog niza pohranjuju se kontinuirano, ali svi nizovi možda neće biti kontinuirano pohranjeni u memoriji. C vam pruža dodatan i jednostavniji pristup gdje možete koristiti posebnu podatkovnu strukturu, tj. strukturu, u kojoj možete grupirati sve informacije različitih tipova podataka o entitetu.

Što je Struktura

Struktura u c-u korisnički je definirana vrsta podataka koja nam omogućuje pohranjivanje zbirke različitih vrsta podataka. Svaki element strukture naziva se član. Strukture ca; simulirati korištenje klasa i predložaka jer može pohraniti različite informacije

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The ,struct ključna riječ se koristi za definiranje strukture. Pogledajmo sintaksu za definiranje strukture u c.

 struct structure_name { data_type member1; data_type member2; . . data_type memeberN; }; 

Pogledajmo primjer za definiranje strukture za zaposlenika entiteta u c.

 struct employee { int id; char name[20]; float salary; }; 

Sljedeća slika prikazuje raspodjelu memorije strukture zaposlenika koja je definirana u gornjem primjeru.

Ovdje, strukturirati je ključna riječ; zaposlenik je naziv strukture; iskaznica , Ime , i plaća su članovi ili polja strukture. Razumimo to prema donjem dijagramu:

Deklaracija strukturne varijable

Možemo deklarirati varijablu za strukturu tako da možemo lako pristupiti članu strukture. Postoje dva načina za deklariranje varijable strukture:

je odnos

1. Pomoću ključne riječi struct unutar funkcije main().
2. Deklaracijom varijable u trenutku definiranja strukture.

1. način:

Pogledajmo primjer za deklariranje varijable strukture pomoću ključne riječi struct. Treba se deklarirati unutar glavne funkcije.

 struct employee { int id; char name[50]; float salary; }; 

Sada napišite zadani kod unutar funkcije main().

 struct employee e1, e2; 

Varijable e1 i e2 mogu se koristiti za pristup vrijednostima pohranjenim u strukturi. Ovdje se e1 i e2 mogu tretirati na isti način kao i objekti u C++ i Java .

2. način:

alfa-beta rezidba

Pogledajmo još jedan način za deklariranje varijable u vrijeme definiranja strukture.

 struct employee { int id; char name[50]; float salary; }e1,e2; 

Koji pristup je dobar

Ako broj varijabli nije fiksan, upotrijebite 1. pristup. Omogućuje vam fleksibilnost deklariranja strukturne varijable mnogo puta.

Ako ne. varijabli su fiksne, koristite 2. pristup. Sprema vaš kod za deklariranje varijable u funkciji main().

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Pristup članovima strukture

Postoje dva načina za pristup članovima strukture:

1. Autor . (član ili operator točka)
2. By -> (operator pokazivača strukture)

Pogledajmo kod za pristup iskaznica član p1 varijabla po. (član) operator.

 p1.id 

C Primjer strukture

Pogledajmo jednostavan primjer strukture u jeziku C.

 #include #include struct employee { int id; char name[50]; }e1; //declaring e1 variable for structure int main( ) { //store first employee information e1.id=101; strcpy(e1.name, 'Sonoo Jaiswal');//copying string into char array //printing first employee information printf( 'employee 1 id : %d
', e1.id); printf( 'employee 1 name : %s
', e1.name); return 0; } 

Izlaz:

 employee 1 id : 101 employee 1 name : Sonoo Jaiswal 

Pogledajmo još jedan primjer strukture u C jezik za pohranu informacija o mnogim zaposlenicima.

 #include #include struct employee { int id; char name[50]; float salary; }e1,e2; //declaring e1 and e2 variables for structure int main( ) { //store first employee information e1.id=101; strcpy(e1.name, 'Sonoo Jaiswal');//copying string into char array e1.salary=56000; //store second employee information e2.id=102; strcpy(e2.name, 'James Bond'); e2.salary=126000; //printing first employee information printf( 'employee 1 id : %d
', e1.id); printf( 'employee 1 name : %s
', e1.name); printf( 'employee 1 salary : %f
', e1.salary); //printing second employee information printf( 'employee 2 id : %d
', e2.id); printf( 'employee 2 name : %s
', e2.name); printf( 'employee 2 salary : %f
', e2.salary); return 0; } 

Izlaz:

 employee 1 id : 101 employee 1 name : Sonoo Jaiswal employee 1 salary : 56000.000000 employee 2 id : 102 employee 2 name : James Bond employee 2 salary : 126000.000000