Understanding pointer-to-pointer in c

[user1234]

So I wanted to understand pointers-to-pointers in c, especially when using linked lists.

What I have assumed a pointer to be, is that it is a space in PC's ram that has been used to save addresses of other spaces (variables).

Is that correct? And if it is correct then how would you define pointer-to-pointer?

Thanks!

[rockedge]

That is correct.

A pointer to a pointer is a form of multiple indirection, or a chain of pointers. Normally, 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, which points to the location that contains the actual value

Example code:

Code: Select all

#include <stdio.h>
 
int main () {

   int  var;
   int  *ptr;
   int  **pptr;

   var = 3000;

   /* take the address of var */
   ptr = &var;

   /* take the address of ptr using address of operator & */
   pptr = &ptr;

   /* take the 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);

   return 0;
}

When compiled and run the code produces:

Code: Select all

Value of var = 3000
Value available at *ptr = 3000
Value available at **pptr = 3000

[some1]

https://www.tutorialspoint.co/m/cprogra ... ointer.htm