Memory And Pointer And The Indirection Operator In C Language

Indian Mirchi

8 years ago

Pointers and the indirection operator:-

The two fundamental operators used with the pointers are:

1. address operator &

2. indirection operator *

Example

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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