C – Pointer

• C Pointer is a variable that stores/points the address of another variable.
• C Pointer is used to allocate memory dynamically i.e. at run time.
• The variable might be any of the data type such as int, float, char, double, short etc.

Syntax : data_type *var_name;
Example : int *p;  char *p;

• Where, * is used to denote that “p” is pointer variable and not a normal variable.

Key points to remember about pointers in C:

• Normal variable stores the value whereas pointer variable stores the address of the variable.
• The content of the C pointer always be a whole number i.e. address.
• Always C pointer is initialized to null, i.e. int *p = null.
• The value of null pointer is 0.

• & symbol is used to get the address of the variable.
• * symbol is used to get the value of the variable that the pointer is pointing to.
• If pointer is assigned to NULL, it means it is pointing to nothing.
• Two pointers can be subtracted to know how many elements are available between these two pointers.

• But, Pointer addition, multiplication, division are not allowed.
• The size of any pointer is 2 byte (for 16 bit compiler).

Example program for pointer in C:

#include <stdio.h>

int main()
{
        int *ptr, q;
        q = 50;  
        /* address of q is assigned to ptr       */
        ptr = &q;     
        /* display q's value using ptr variable */      
        printf("%d", *ptr); 
        return 0;
}

Output:

50