C Foundation

What is C? C Compiler Installation C Extensions C Compiler C Interpreter C Program Structure

C Basics

C Keywords C Data Types C Identifiers C Variables C Constant C Escape Sequences C Constant and Volatile C Typecast


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()

C Reference

All ASCII Code Basic C Questions

C Interview

C Interview Sets All Star Patterns All Number Patterns All Alphabet Patterns All Series Patterns
The ones who are crazy enough to think they can change the world are the ones who do.
- Steve Jobs

C free()

Why free()

A good person will recycle things whereas good programmer will recycle the memory. In most components such as microprocessor we have only certain range of memory spaces. It's programmer's responsibility to reuse the memory, If you found any data which will no longer get used, then you can delete the data from the memory to free some spaces for future use. To free memory spaces you can use free() inbuilt memory function.

free in c

What is free?

  • free() deallocates a memory block which are all allocated previously by malloc, calloc and realloc.
  • free() is mainly used when the data in the memory blocks will no longer required.

free() Syntax

free ( variable );

C Program - free()

In the following program we will allocate space for number variable using malloc() inbuilt memory function and then we will initialize that variable with some data, finally we will deallocate or clear the memory of number variable using free() inbuilt memory function in c.

#include <stdio.h>
#include <stdlib.h>
int main()
int *numbers = (int*)malloc(4* sizeof(int));
int i;
numbers[0] = 0;
numbers[1] = 1;
numbers[2] = 2;
numbers[3] = 3;
printf("\nStored integers are ");
for(i = 0; i < 4; i++)
printf("\numbers[%d] = %d ", i, numbers[i]);
return 0;
  • numbers[0] = 0
  • numbers[1] = 0
  • numbers[2] = 0
  • numbers[3] = 0

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