Pointers and the indirection operator:-
The two fundamental operators used with the pointers are:
1. address operator &
2. indirection operator *
Example
main( )
{
int a = 5;
int *p; /*pointer declaration*/
p= &a; /*copying address of variable a to the pointer p*/
*p = 10; /*indirection or use of pointer to Change the value of variable a*/
printf(“%d”, a);
printf(“%d”,*p);
printf(“%d”,*(&a));
}
All the printf statements in the above program will give the output as 10. Since the variable p is not an ordinary variable like any other integer variable. It is A variable which stores the address of some other variable (a in this case).
Since p is a variable, the compiler must provide memory to this variable also. Any type of pointer gets two bytes in the memory. int *p1; float *p2; char *p3; all pointers p1, p2, p3 get 2 bytes each.
Memory and Pointer:-
Suppose if three pointers are declared for int, float, char. All the three pointers will occupy 2 bytes in the memory. This is because all the memory addresses are integer values ranging from 0 to 65536. Thus we can say that a pointer irrespective of its type is storing the addresses as integer values and each integer requires only two bytes.
Example
main( )
{
int a = 5,*p1;
float b=2.5,*p2;
char c=’a’,*p3;
p1= &a;
p2= &b;
p3= &c;
printf(“%d”,sizeof(p1));
printf(“%d”,sizeof(p2));
printf(“%d”,sizeof(p3));
}
Output:
2 2 2
