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Nested structure in C is nothing but structure within a structure. One structure can be declared inside other structure as we declare structure members inside a structure. The structure variables can be a normal structure variable or a pointer variable to access the data. You can learn the concepts in this section.

Structure within structure in C using normal variable

This program explains how to use structure within structure in C using normal variable. university_detail structure is declared inside student_detail structure in this program. Both structure variables are normal structure variables.

Please note that members of university_detail structure are accessed by 2 dot(.) operator and members of student_detail structure are accessed by single dot(.) operator.

#include 
#include 
 
struct university_detail
{
    int u_id;
    char u_name[50];
};
 
struct student_detail 
{
    int s_id;
    char s_name[20];
    float s_marks;
    // structure within structure
    struct university_detail u_data;
}stu_data;
 
int main() 
{
    struct student_detail stu_data = {1, "Rambo", 99.5, 89145,
                                       "Peace University"};
    printf(" Id is: %d \n", stu_data.s_id);
    printf(" Name is: %s \n", stu_data.s_name);
    printf(" Percentage is: %f \n\n", stu_data.s_marks);
 
    printf(" College Id is: %d \n", 
                    stu_data.u_data.u_id);
    printf(" College Name is: %s \n", 
                    stu_data.u_data.u_name);
    return 0;
}

 Id is: 1
 Name is: Rambo
 Percentage is: 99.500000

 College Id is: 89145
 College Name is: Peace University
Press any key to continue . . .

Structure within structure in C using pointer variable

This program explains how to use structure within structure in C using pointer variable. university_detail structure is declared inside student_detail structure in this program. one normal structure variable and one pointer structure variable is used in this program.

Please note that combination of .(dot) and ->(arrow) operators are used to access the structure member which is declared inside the structure.

Example Program

#include 
#include 
 
struct university_detail
{
    int u_id;
    char u_name[50];
};
 
struct student_detail 
{
    int s_id;
    char s_name[20];
    float s_marks;
    // structure within structure
    struct university_detail u_data;
}stu_data, *stu_data_ptr;
 
int main() 
{
    struct student_detail stu_data = {21, "Rambo", 99.5, 89145,
                                       "Peace University"};
                                       
    stu_data_ptr = &stu_data;                                  
                                       
    printf(" Id is: %d \n", stu_data_ptr->s_id);
    printf(" Name is: %s \n", stu_data_ptr->s_name);
    printf(" Percentage is: %f \n\n", 
                         stu_data_ptr->s_marks);
 
    printf(" College Id is: %d \n", 
                         stu_data_ptr->u_data.u_id);
    printf(" College Name is: %s \n", 
                      stu_data_ptr->u_data.u_name);
    return 0;
}

Output

 Id is: 21
 Name is: Rambo
 Percentage is: 99.500000

 College Id is: 89145
 College Name is: Peace University
Press any key to continue . . .

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