Array of Structures in C

There can be array of structures in C programming to store many information of different data types. The array of structures is also known as collection of structures.
see an example of structure with array that stores information of 5 students and prints it.
#include <stdio.h>
#include <string.h>
struct student{  
int rollno;  
char name[20];  
};  
void main(){  
int i;  
struct student st[4];    
printf("Enter Records of 4 students");  
for(i=0;i<4;i++){  
printf("\nEnter Rollno:");  
scanf("%d",&st[i].rollno);  
printf("\nEnter Name:");  
scanf("%s",&st[i].name);  
}  
printf("\nStudent Information List:");  
for(i=0;i<4;i++){  
printf("\nRollno:%d, Name:%s",st[i].rollno,st[i].name);  
}  
}
output:
Enter Records of 4 students
Enter Rollno: 1
Enter Name: pramesh
Enter Rollno: 2
Enter Name: Ranjan
Enter Rollno: 3
Enter Name: deepak
Enter Rollno: 4
Enter Name: anjali
Student Information List:
Rollno:1, Name: pramesh
Rollno:2, Name: Ranjan
Rollno:3, Name: deepak
Rollno:4, Name: anjali

Nested Structure in C

Nested structure in c language can have another structure as a member. There are two ways to define nested structure in c language.
By separate structure
By Embedded structure

Separate structure

We can create 2 structures, but dependent structure should be used inside the main structure as a member. Let's see the code of nested structure.
struct Date  
   {  
int dd;  
int mm;  
int yyyy;   
 };  
struct student
  {     
int id;  
char name[30];  
struct Date doj;  
}stu1;
As you can see, doj (date of joining) is the variable of type Date. Here doj is used as a member in student structure. In this way, we can use Date structure in many structures.

Embedded structure

We can define structure within the structure also. It requires less code than previous way. But it can't be used in many structures
struct Student { 
int id;  
char name[30];  
struct Date  
 {  
int dd;  
int mm;  
int yyyy;   
 } doj;  
} stu1;

Accessing Nested Structure

We can access the member of nested structure by Outer_Structure.Nested_Structure.member as given below:
s1.doj.dd  
s1.doj.mm  
s1.doj.yyyy

Nested Structure example

see a simple example of nested structure in C language. 
#include <stdio.h>
#include <string.h>
struct Student {     
int id;  
char name[30];  
struct Date {  
int dd;  
int mm;  
int yyyy;   
 } doj;  
 } s1;  
int main( ) {  
 //storing student information  
s1.id=110;  
strcpy(s1.name, "pramesh gupta");    //copying string into char array  
s1.doj.dd=10;  
s1.doj.mm=8;  
s1.doj.yyyy=2017;  
      //printing first student information  
printf( "student id : %d\n", s1.id);  
printf( "student name : %s\n", s1.name);  
printf( "student date of joining (dd/mm/yyyy) : %d/%d/%d\n", s1.doj.dd,s1.doj.mm,s1.doj.yyyy);  
 return 0;  
    }  
Output:
student id : 110
student name : pramesh gupta 
student date of joining (dd/mm/yyyy) : 10/8/2017