C Programming Code Examples

C > Pointers Code Examples

Pointer to Pointer (Double Pointer)

Pointer to Pointer (Double Pointer)

We already know that a pointer holds the address of another variable of same type. When a pointer holds the address of another pointer then such type of pointer is known as pointer-to-pointer or double pointer. In this guide, we will learn what is a double pointer, how to declare them and how to use them in C programming. To understand this concept, you should know the basics of pointers.

#include <stdio.h>
int main()
{
     int num=123;

     //A normal pointer pointer2
     int *pointer2;

     //This pointer pointer2 is a double pointer
     int **pointer1;

     /* Assigning the address of variable num to the
      * pointer pointer2
      */
     pointer2 = #

     /* Assigning the address of pointer pointer2 to the
      * pointer-to-pointer pointer1
      */
     pointer1 = &pointer2;

     /* Possible ways to find value of variable num*/
     printf("\n Value of num is: %d", num);
     printf("\n Value of num using pointer2 is: %d", *pointer2);
     printf("\n Value of num using pointer1 is: %d", **pointer1);

     /*Possible ways to find address of num*/
     printf("\n Address of num is: %p", &num);
     printf("\n Address of num using pointer2 is: %p", pointer2);
     printf("\n Address of num using pointer1 is: %p", *pointer1);

     /*Find value of pointer*/
     printf("\n Value of Pointer pointer2 is: %p", pointer2);
     printf("\n Value of Pointer pointer2 using pointer1 is: %p", *pointer1);

     /*Ways to find address of pointer*/
     printf("\n Address of Pointer pointer2 is:%p",&pointer2);
     printf("\n Address of Pointer pointer2 using pointer1 is:%p",pointer1);

     /*Double pointer value and address*/
     printf("\n Value of Pointer pointer1 is:%p",pointer1);
     printf("\n Address of Pointer pointer1 is:%p",&pointer1);

     return 0;
}