This document discusses double pointers or pointer-to-pointers in C. A double pointer is a pointer that holds the address of another pointer variable. The first pointer stores the address of a variable, while the second pointer stores the address of the first pointer. To declare a double pointer in C, an additional asterisk is placed before the pointer variable name, such as int **ptr, which declares a pointer that points to a pointer of type int.

1. Double Pointer (Pointer to
pointer)
Prepared By: Mr. Sangram A. Patil
Assistant Professor PVPIT,Budhgaon

2. Double Pointer
 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.
 The first pointer is used to store the address of the variable. And the second
pointer is used to store the address of the first pointer. That is why they are also
known as double pointers.

3. How to declare a pointer to pointer in C?
 Declaring Pointer to Pointer is similar to declaring pointer in C. The difference is
we have to place an additional ‘*’ before the name of pointer.
 Syntax:
int **ptr; // declaring double pointers
 Here, we have used two indirection operator(*) which stores and points to the
address of a pointer variable i.e, int *
*.

4. int a =10;
int *p1;
int **p2;
p1 = &a;
P2=&p1;