In this section of the C programming tutorial, you will learn about structures and unions. We will first have a look at structures.
What is structure in the C programming language?
Structure(defined as struct) in C programming language is a complex data type that defines a physically grouped list of variables under one name in a memory block that allows you to access different variables with a single pointer or by the declared name structure that returns the same address.
- If you want to access members of a structure in C, you must change the structure variable.
- Many structure variables can be declared for one structure, and memory will be allocated for each.
- Structure data type may contain other types of data, so it is used for records of mixed data types, such as recording a directory on the hard disk.
Declaration of structure in C
The general syntax for a struct declaration in C is:
struct tag_name {
type member1;
type member2;
...
type member;
};
Defining a Structure
The general syntax for a defining a struct in C is:
struct [structure tag] {
member1 definition;
member2 definition;
...
member definition;
} [one or more structure variables];
| Using normal variable | Using pointer variable |
| Syntax: struct tag_name { data type var_name1; data type var_name2; data type var_name3; }; |
Syntax: struct tag_name { data type var_name1; data type var_name2; data type var_name3; }; |
| Example: struct student { int mark; char name[10]; float average; }; |
Example: struct student { int mark; char name[10]; float average; }; |
| Declaring structure using normal variable: struct student report; |
Declaring structure using pointer variable: struct student *report, rep; |
| Initializing structure using normal variable: struct student report = {100, “Mani”, 99.5}; |
Initializing structure using pointer variable: struct student rep = {100, “Mani”, 99.5}; report = &rep; |
| Accessing structure members using normal variable: report.mark; report.name; report.average; |
Accessing structure members using pointer variable: report -> mark; report -> name; report -> average; |
Example of structure in C programming language:
The following example shows how to use a structure in a program.
#include <stdio.h>
#include <string.h>
struct student
{
int rollno;
char name[60];
}s1; //declaring s1 variable for structure
void main( )
{
s1.rollno=234;
strcpy(s1.name, “John”);//copying string into char array
//printing first employee information
printf( "Rollno : %d\n", s1.rollno);
printf( "Name : %s\n", s1.name);
}
Output:
Rollno : 234
Name : John