C Foundation

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C Basics

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What is Operator C Comma Operator C Arithmetic Operators C Relational Operators C Logical Operators C Bitwise Operators C Conditional Operators C : : Operator C Operator Priority

Basic IO's

Basic IO's C Formatted Functions C Unformatted Functions C Common Functions

Control Statements

What is Control Statement C if Statement C if else Statement C Nested if Statement C Else if Statement C Break Statement C Continue Statement C Switch Statement C Goto Statement


What is Control Loop C for Loop C Nested for Loop C while Loop C Nested while Loop C do while Loop C Nested do while loop


What is Function C User Defined Functions C Recursion C Passing Parameters


Scope C Local Scope C Global Scope

Storage Classes

What is Storage Class C Auto C Extern C Static C Register


What is Array C One Dimensional Array C Two Dimensional Array C Multi Dimensional Array C Arrays Of Strings


What is String C String Functions


What is Pointer C Pointers Arithmetic C Pointer to Pointer C Pointers and Arrays C Pointers and Strings C Pointer to Functions Void Pointers Null Pointers C Null and Void Pointer


What is Structure C Struct within Struct C Array within Structure C Pointer to Structure C Structure and Function C Enum C Bitfield Structure C Type def


What is Union


What is File C read a file C write a file C File Handling C Error Handling C Low Level Disk I/O C Other file functions

Memory Allocation

What is Memory Allocation C Malloc() C Calloc() C Free() C Realloc() C Coreleft()

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The ones who are crazy enough to think they can change the world are the ones who do.
- Steve Jobs

C Pointer to Pointer

A pointer variable containing the address of another pointer variable is known as pointer to pointer or a chain of pointers. The pointer variable that holds the address of another variable should be declared with additional asterisk (*).

pointer to pointer in c

Pointer To Pointer First Look

int i = 5, *ptr;
int **ptrptr;     //declaration of pointer with additional asterisk
ptr = &i;
ptrptr = &ptr;     //assigning a pointer variable address to pointer (ptrptr)

C Program - Pointer to Pointer

#include <stdio.h>
int main()
int i = 5;
int *ptr, **ptrptr;
ptr = &i;
ptrptr = &ptr;
printf("The value of i = %d ", i);
printf("\nThe value of ptr = %d ", *ptr);
printf("\nThe value of ptrptr = %d ", **ptrptr);
return 0;
  • The value of i = 5
  • The value of ptr = 5
  • The value of ptrptr = 5


In the above program, ptr is declared as an integer pointer variable. The variable ptrptr is also declared as integer pointer variable to hold another pointer variable ptr.

C Program - Pointer to Pointer in Array

#include <stdio.h>
void function(char**);
int main()
char *arr[] = { "ant", "bat", "cat", "dog", "egg", "fly" };
return 0;
void function(char **ptr)
char *ptr1;
ptr1 = (ptr += sizeof(int))[-2];
printf("%s\n", ptr1);
  • cat


Here function() gives the address of first value("ant") in an arr. This address is summationed by a sizeof(int) which is 4. Now the address in ptr points the value eggs, which is then reduced by 2. Now it points to the value cat which is finally displayed.

Purpose Of Pointer To Pointer

  • Whenever you are insisted to declare pointer array, then you have to go for pointer to pointer variable to access the value in an array.

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