What is the double pointer.

Answer 1

I think you mean by Pointer pointing to a Pointer.

Example :
/*C program to demonstrate pointer to pointer */

int main()
{
int var = 789;

// pointer for var
int *ptr2;

// double pointer for ptr2
int **ptr1;

// storing address of var in ptr2
ptr2 = &var;

// Storing address of ptr2 in ptr1
ptr1 = &ptr2;

// Displaying value of var using
// both single and double pointers
printf("Value of var = %d\n", var );
printf("Value of var using single pointer = %d\n", *ptr2 );
printf("Value of var using double pointer = %d\n", **ptr1);

return 0;
}

Answer 2

Do you mean a pointer to a pointer?