Pointer and Its Key Points

WHAT IS POINTER?

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

• Pointer 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 a pointer in C 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:

#include <stdio.h>

int main()

{

   int *ptr, p;

   p = 123;

   /* address of p is assigned to ptr */

   ptr = &p;

   /* display p's value using ptr variable */

   printf("%d", *ptr);

   return 0;

}

 Output:

            123