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In this tutorial we will be learning dynamic memory allocation. It is used to allocate memory dynamically at run time.

C dynamic memory allocation

Consider the below program where we have declared an array of size 100.

#include<stdio.h>
int main() {
   int a[100], i;
   for (i = 0; i < 100; i++)
      scanf("%d", &a[i]);
   printf("\nPrinting array -");
   for (i = 0; i < 100; i++)
      scanf("A[%d]", &a[i]);
    return (0);
}

In this program we are accepting 100 numbers from the user and printing the array of size 100.

Some scenarios when you want dynamic allocation -

We cannot predict at compile time how much size is required at run time. Memory requirement can be insufficient or can be more than sufficient.

Dynamic memory allocation in c programming will allow program to allocate/release memory at run time (i.e while running program)

Important Notes

Point,Explanation
Header File,stdlib.h
Total Functions,4
Header File,stdlib.h

Dynamic Memory Allocation : malloc / Calloc function

1. Dynamic Memory Allocation means to Allocate Memory at run-time i.e at the time of Program execution 
2. In C malloc and calloc functions are used to allocate memory at Run-time
3. It returns pointer to block of n bytes of memory allocated during run-time
4. If the Process fails i.e if it is unable to allocate memory then returns NULL
5. Note : Typecasting is necessary.

Must See :

1. Calloc
2. Malloc