What is Malloc() function in C Programming Language?

What is Malloc() function in C Programming Language?

A malloc() function is used for  dynamic memory allocation. It is defined in stdlib.h or malloc.h depending on the operating system. Memory allocation by malloc() is persistent.  

• void  *malloc(size_t size);

Example:

• #include<stdio.h>
• #include<stdlib.h>
• void main()
• {
•           int array[10];
•           int *ptr = (int *) malloc(10 * sizeof (int));
• if (ptr == NULL)
• {
• }
•           else
•          {
•                   free(ptr);
•                   ptr=NULL;
•           }
• }

What is Calloc() function in C Programming Language?

What is Calloc() function in C Programming Language?

A calloc() function allocates space for an array of elements of a certain size and initializes the memory to zero. 

• void  *calloc(size_t num, size_t size);

Here num is number of objects to allocate and size is the size of each objects. If the allocation is successful then function returns a Pointer to the first byte and if allocation fails then the function returns NULL. 

Examples:

• #include<stdio.h>
• #include<stdlib.h>
• void main()
• {
•           unsigned a;
•           int *ptr;
•           printf(“Enter the number to allocate:-”);
•           scanf("%d", &a);
•           ptr= (int*) calloc(a, sizeof(int));
•           if(ptr!=NULL)
•           {
•                      puts("Memory allocation successful");
•            }
•           else
•           {
•                     puts("Memory allocation failed");
•           }
•           return(0);
• }

Output:-

• Enter the number to allocate:- 200
• Memory allocation successful
• Enter the number to allocate:- 111111111111
• Memory allocation failed