C Pointer to pointer

Pointers to pointers are a form of multilevel indirection, or a pointer chain. Typically, a pointer contains the address of a variable. When we define a pointer to a pointer, the first pointer contains the address of the second pointer, and the second pointer points to the position that contains the actual value.

A pointer variable pointing to a pointer must be declared as follows, placing two asterisks before the variable name. For example, the following declares a pointer to the INT type pointer:

int * *var;

When a target value is indirectly directed to another pointer by one pointer, access to the value requires the use of two asterisk operators, as shown in the following example:

1#include <stdio.h>2  3 intMain ()4 {5    int  var;6    int*ptr;7    int**pptr;8 9    var= the;Ten  One    /*get the address of Var*/ APTR = &var; -  -    /*Use the operator & get the address of PTR*/ thePptr = &ptr; -  -    /*get a value using Pptr*/ -printf"Value of var =%d\n",var ); +printf"Value available at *ptr =%d\n", *ptr); -printf"Value available at **pptr =%d\n", **pptr); +  A    return 0; at}

When the above code is compiled and executed, it produces the following results:

var  the   about

C Pointer to pointer