Structures in C

A structure is a user defined data type in C/C++. A structure creates a data type that can be used to group items of possibly different types into a single type.

Suppose if we want to store the employee details like name, age, department and gender we can create a user-defined type which is structure.

Structure will allocate individual address to each of the member variables.

Define a Structure

The struct keyword is used to define a structure. The struct defines a new data type which is a collection of primary and derived data types.

Syntax

struct [structure_tag]
{
    //member variable 1
    //member variable 2
    //member variable 3
    ...
}[structure_variables];

To create a structure we use struct keyword and provide a tag name to it as an identifier. Now inside the body of the struct we define the member variables and after closing the struct, we can specify one or more structure variables. This is optional.

Example

struct Employee
{
    char name[25];
    int age;
    char department[10];
    char gender;
};

Here the structure name is Employee with variables name, age, department and gender.

Declaring Structure variable

Method 1

struct Employee
{
    char name[25];
    int age;
    char department[10];
    char gender;
};
// declaring variables of struct Employee
struct Employee emp1, emp2; 

Method 2

struct Employee
{
    char name[25];
    int age;
    char department[10];
    char gender;
}emp1,emp2;

The recommended method to use structure is the method 1.

How to access Structure Members:

Structure members have no meaning individually without the structure. In order to assign a value to any structure member, the member name must be linked with the structure variable using a dot . operator also called period or member access operator.

Example

#include<stdio.h>
#include<string.h>

struct Employee
{
    char name[25];
    int age;
    char department[10];
    char gender;
};

int main()
{
    struct Employee emp1;
	// using string function to add name
	printf("Enter employee name\n");
	scanf("%s", emp1.name);
	printf("Enter employee age\n");
	scanf("%d", emp1.age);
	printf("Enter employee gender\n");
	scanf("%c", emp1.gender);
	
    printf("Employee Name %s\n", emp1.name);
    printf("Employee Age: %d\n", emp1.age);
	printf("Employee Gender: %c\n", emp1.gender);
    return 0;
}

Output

Enter employee name
Andrew
Enter employee age
25
Enter employee gender
M
Employee Name:
Andrew
Employee Age:
25
Employee Gender:
M

Array of Structures

Suppose if we need to get the details of multiple employees, instead of creating multiple structure variables we can create array of structures.

Syntax

struct Employee emp[10];

Now each element of array emp is of type Employee.

Example

#include<stdio.h>
#include<string.h>

struct Employee
{
    char name[25];
    int age;
    char gender;
};

int main()
{
    struct Employee emp[5];
	for(int i=0;i<5;i++;)
	{
	// using string function to add name
	  printf("Enter employee name\n");
	  scanf("%s", emp1[i].name);
	  printf("Enter employee age\n");
	  scanf("%d", emp1[i].age);
	  printf("Enter employee gender\n");
	  scanf("%c", emp1[i].gender);
	}
	printf("Employee Records");
	for(int j=0;j<5;j++)
	{
	  printf("Employee Name %s\n", s1.name);
      printf("Employee Age: %d\n", s1.age);
	  printf("Employee Gender: %c\n", s1.gender);
	  printf("-------------------");
	}
    return 0;
}