structure is declared with the keyword struct and structure 
variables occupy individual memory location.But Unoin is 
declared with the keyword union and its variables are 
allocated to a memory at which the highest byte of the 
variable is declared.

Thanks for these answer renuka..............
it means that 
struct student
{
int i;
char a,b;
}
it occupy 4 bytes of memory..........
 and in case of union
union student
{
int i;
char a,b;
}
 it occupies only 2 byte memory.............

Am i write or wrong

union is better then structure.union is declared with 
keyword union.it can store more data which can store at
hights byte of veeriable is declared.structure is declred 
a keyword struct.it will store for indivisul memory space.

Kapildalke -> u are rite..

the differance between a structure and union is that,

in structure memory is allocated to each and every element 
of the structure.

in union memory allocated is only of the element which 
requires maximum memory.

all of you are correct. ya, structure is declared with the 
keyword struct and structure 
variables occupy individual memory location.But Unoin is 
declared with the keyword union and its variables are 
allocated to a memory at which the highest byte of the 
variable which is declared.