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

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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

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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


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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

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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 Malloc()

Why Malloc?

Now it's time to partition the microprocessor's memory to your 6 teams of your startup company, If you want to allocate contiguous memory location to every team, then malloc() will help you out there.

malloc in c

What is Malloc?

  • malloc() is the programmer's shorthand to represent memory allocation.
  • malloc() allocates a block of size bytes to a program from the heap.
  • malloc() allocate an exact quantity of memory explicitly to a program, when required.
  • allocation of memory is done in contiguous location.

Syntax - Malloc()

void *malloc  (size_t size);

C program - without using malloc() for unknown data

In the following program we will consider that we want to store two integer data , but unfortunately we are forced to store 4 integer data, but we allocated an array of size 2. Let us see what happen when we add 4 integer data in an array whose size is 2.

#include <stdio.h>
int main()
int numbers[2], i;
numbers[0] = 0;
numbers[1] = 1;
numbers[2] = 2;
numbers[3] = 3;
printf("\nStored integers are ");
for(i = 0; i < 4; i++)
printf("\nnumbers[%d] = %d ", i, numbers[i]);
return 0;
  • numbers[0] = 0
  • numbers[1] = 1
  • numbers[2] = 4132608
  • numbers[3] = 4132610

C program - using malloc() for unknown data

Let us redesign the above program using malloc() instead of array because when a memory is allocated either by using malloc() or calloc() inbuilt function, it can be reallocated using realloc() inbuilt function when some memory is demanded.

#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("\nnumbers[%d] = %d ", i, numbers[i]);
return 0;
  • numbers[0] = 0
  • numbers[1] = 1
  • numbers[2] = 2
  • numbers[3] = 3


Programmer might thinks that malloc() is initialized at the beginning itself, then why array should not. Simply, malloc() is capable of reallocation i.e.) extending its size. But unfortunately array can't be reallocated. Please check realloc to clear all your doubt's in memory allocation.

Did You Know?

Once a block memory is allocated by using malloc() inbuilt function. Each individual blocks of memory are represented by some garbage value.

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