Memory Allocation Of C Structure Program

Structure within structure in C using pointer variable

#include 

#include 

struct student_college_detail

{

    int college_id;

    char college_name[50];

};

struct student_detail 

{

    int id;

    char name[20];

    float percentage;

    struct student_college_detail clg_data; 

}stu_data, *stu_data_ptr;

int main() 

{

  struct student_detail stu_data = {1, "Raju", 90.5, 71145, 

                                    "Anna University"};

    stu_data_ptr = &stu_data;

    printf(" Id is: %d \n", stu_data_ptr->id);

    printf(" Name is: %s \n", stu_data_ptr->name);

    printf(" Percentage is: %f \n\n", 

                         stu_data_ptr->percentage);

    printf(" College Id is: %d \n", 

                         stu_data_ptr->clg_data.college_id);

    printf(" College Name is: %s \n", 

                      stu_data_ptr->clg_data.college_name);

    return 0;

}

Output

Id is: 1
Name is: Raju
Percentage is: 90.500000

College Id is: 71145
College Name is: Anna University

Memory allocation in C structure

#include 

#include

#include 

struct student 

{

       int id1;

       int id2;

       char a;

       char b;

       float percentage;

};

int main() 

{

    int i;

    clrscr();

    struct student record1 = {1, 2, 'A', 'B', 90.5};

    printf("size of structure in bytes : %d\n", 

                           sizeof(record1));

    printf("\nAddress of id1        = %u", &record1.id1 );

    printf("\nAddress of id2        = %u", &record1.id2 );

    printf("\nAddress of a          = %u", &record1.a );

    printf("\nAddress of b          = %u", &record1.b );

    printf("\nAddress of percentage = %u",&record1.percentage);

    return 0;

}

 Output

size of structure in bytes : 16
Address of id1 = 675376768
Address of id2 = 675376772
Address of a = 675376776
Address of b = 675376777
Address of percentage = 675376780

Structure padding in C

#include 

#include

#include 

struct structure1 

{

       int id1;

       int id2;

       char name;

       char c;

       float percentage;

};

struct structure2 

{

       int id1;

       char name;

       int id2;

       char c;

       float percentage;                      

};

int main() 

{

    struct structure1 a;

    struct structure2 b;

    printf("size of structure1 in bytes : %d\n", sizeof(a));

    printf ( "\n   Address of id1        = %u", &a.id1 );

    printf ( "\n   Address of id2        = %u", &a.id2 );

    printf ( "\n   Address of name       = %u", &a.name );

    printf ( "\n   Address of c          = %u", &a.c );

    printf ( "\n   Address of percentage = %u",&a.percentage );

    printf("   \n\nsize of structure2 in bytes : %d\n",sizeof(b));

    printf ( "\n   Address of id1        = %u", &b.id1 );

    printf ( "\n   Address of name       = %u", &b.name );

    printf ( "\n   Address of id2        = %u", &b.id2 );

    printf ( "\n   Address of c          = %u", &b.c );

    printf ( "\n   Address of percentage = %u",&b.percentage );

    getchar();

    return 0;

}

Output

size of structure1 in bytes : 16
Address of id1 = 1297339856
Address of id2 = 1297339860
Address of name = 1297339864
Address of c = 1297339865
Address of percentage = 1297339868
size of structure2 in bytes: 20
Address of id1 = 1297339824
Address of name = 1297339828
Address of id2 = 1297339832
Address of c = 1297339836
Address of percentage = 1297339840