Structure padding is a concept in C that adds one or more empty bytes between the memory addresses to align the data in memory.

Let's first understand the structure padding in C.

//displaying first_structure and second_structure output

printf("===================FIRST STRUCTURE===============================\n");

printf("size of first_structure in bytes : %d\n",sizeof(s1));

printf ( "\n   Address of rollNo1        = %u",&s1.rollNo1 );

printf ( "\n   Address of rollNo2        = %u",&s1.rollNo2 );

printf ( "\n   Address of firstName       = %u",&s1.firstName );

printf ( "\n   Address of character          = %u",&s1.character);

printf ( "\n   Address of salary = %u",&s1.salary);

printf("\n===================SECOND STRUCTURE===============================\n");

printf("size of second_structure in bytes : %d\n",sizeof(s2));

printf ( "\n   Address of rollNo1        = %u",&s2.rollNo1 );

printf ( "\n   Address of rollNo2        = %u",&s2.rollNo2 );

printf ( "\n   Address of firstName       = %u",&s2.firstName );

printf ( "\n   Address of character          = %u",&s2.character);

printf ( "\n   Address of salary = %u",&s2.salary);

printf("First Name of Employee is :%s\n",e.first_name);

printf("Last Name of Employee is :%s\n", e.last_name);

printf("==================1ST STRUCTURE=========================\n");

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

printf ( "\n   Address of first_name        = %u",&e.first_name);

printf ( "\n   Address of last_name        = %u",&e.last_name );

A few examples will be given along with the padding of structure in C in the latter part of the blog post.

structure padding