What is structure? How to access the elements of structure? How to calculate size of structure? Explain with example.

Question: What is structure? How to access the elements of structure? How to calculate size of structure? Explain with example.

What is structure?

   Structure is a user-defined datatype in C language which allows us to combine data of different types together. Structure helps to construct a complex data type which is more meaningful. It is somewhat similar to an Array, but an array holds data of similar type only.

Accessing Structure Members

• Array elements are accessed using the Subscript variable, Similarly Structure members are accessed using dot [.] operator.
• (.) is called as “Structure member Operator”.
• Use this Operator in between “Structure name” & “member name”

How to access the elements of structure?
Structure members are accessed using dot (.) operator.

1. #include<stdio.h> 
2.   
3. struct Point 
4. { 
5.    int x, y; 
6. }; 
7.   
8. int main() 
9. { 
10.    struct Point p1 = {0, 1}; 
11.   
12.    // Accessing members of point p1 
13.    p1.x = 20; 
14.    printf ("x = %d, y = %d", p1.x, p1.y); 
15.   
16.    return 0; 
17. }

Output:

x = 20, y = 1

Output Screenshot:

How to calculate size of structure?

   Generally, size of structure is addition of size of each member field. But compiler may add some extra bytes for padding/align members appropriately. This is general guideline may differ depending upon compiler/platform you choose. The size is at least sizeof(int) + sizeof(struct node *) + sizeof(struct node *).

• Formula for Calculating Size of Structure:
• Size of Structure 'S' = sizeof(roll) + sizeof(name.
• = 2 + 10 + 2.
• = 14.

Example:

1. /***************************************************
2.  Statement - Calculate Size of Structure
3.  By            - www.info-gtu.in
4.  ************************************************/
5. 
   
6. 
   
7. #include<stdio.h>
8. 
   
9. struct stud {
10.     int roll;
11.     char name[10];
12.     int marks;
13. };
14. 
    
15. int main() {
16.     int size;
17.     struct stud s;
18.     
19.     size = sizeof(s);
20.     printf("nSize of Structure : %d", size);
21.     
22.     return(0);
23. }
24. 
    
25. /*
26.  Explanation:
27.  ---------------
28.  Structure is Collection of elements of the Different data Types.
29.  Size of the Structure Can be Evaluated using “sizeof Operator”
30.  
31.  size = sizeof(s);
32.  
33.  Formula for Calculating Size of Structure:
34.  -------------------------------------------
35.  Size of Structure 'S' = sizeof(roll) + sizeof(name) + sizeof(mark)
36.  = 2 + 10 + 2
37.  = 14
38.  ->Size depends on your computer
39.  
40.  Remember:
41.  ----------
42.  sizeof is Operator not function
43.  sizeof Operator Takes any Variable as Parameter.
44.  */

Output:

nSize of Structure : 20

Output Screenshot: