Nested structure / Structure with in Structure

A structure is a programmer defined datatype where group of different types of data are stored. Like nested loops C permits us to create structure with in another structure. Such structures are called nested structures. Such a nesting of structure more useful when you are working with complex data. In C, structures can be nested in two ways.

Defining One structure as a member of another structure

         One structure can be defined as member of another structure. Let us consider below example, where an employee structure is defines as a member of department structure.

Example:

struct department  

{

  char name[30];

  struct employee

  {

    int eid;

    int sal;

   char eaddress[20];

   }e;

}d;

The innermost members in nested structure (employee) can be accessed as follows.

printf("\n the employee id %d", d.e.eid);

Prints("\n the employee salary %d", d.e.sal);

Defining Nested structure using structure variables

      One can also define nested structure using structure variables. Here we define one structure variable as a member of another structure. Let us consider the following example,

struct dept

{

  int name[30];

  int no;

}

struct employee

{

  int eid;

  int easl;

  struct dept deptname;  // deptname is structure variable of type dept

}

Here in this example, I am defining "deptname" as a member of structure employee.