quick guide

The values of structure variables can be assigned to another
structure variable of the same type using the assignment
operators. It is not necessary to copy the structure elements
piecemeal.

1.
main()
{
struct employee
{
char name[10];
int age;
float sal;
};
struct employee e1={"sanjay",30,1000.00};
struct employee e2,e3;
/* piecemeal copying*/
strcpy(e2.name,e1.name);
e2.age=e1.age;
e2.sal=e1.sal;
/*copying all elements at one time */
e3=e2;
printf("\n %s %d %f",e1.name,e1.age,e1.sal);
printf("\n%s %d %f",e2.name,e2.age,e2.sal);
printf("\n%s %d %f",e3.name,e3.age,e3.sal);
}

OUTPUT:
sanjay 30 1000.0000
sanjay 30 1000.0000
sanjay 30 1000.0000

For copying arrays we have to copy the contents of the
array element by element.This copying of all structure elements
at one time has been possible only because the structure
elements are stored in contiguous memory locations.

2.One structure can be nested within another structure.Using
this facility complex data types can be Created.

Main()
{
struct address
{
char phoneno[15];
char city[30];
int pin;
};
struct emp
{
char name[];
struct address a;
};
struct emp e={"sneha","531046","Texas",507};
printf("\n name=%s phone=%s",e.name,e.a.phoneno);
printf("\n city=%spin=%d" ,e.a.city,e.a.pin);
}

OUTPUT:
name=sneha phone=531046
city=Texas pin=507