Difference Between malloc() and calloc()

webmaster — Fri, 07 Oct 2022 09:22:19 +0000

calloc	malloc
We need to split and pass the memory we want	We can pass how much memory we want.
Ex: p=calloc(5,sizeof(int)	Ex: p=malloc(5,sizeof(int)
Function return void	Functions Return void
Returns starting address but before allocating to us it will zero it. It will clear the previous garbage value.	Returns starting address.
Calloc is slower than malloc	Faster than calloc.
It is safe as compared to malloc	Not safe as calloc.
Dynamic memory allocation	A function which allocates block memory during run time.
There are 4 library routines calloc(), free(), alloc(),and malloc() which is used to allocate memory and free it up during the program execution	Once when a memory space of specific size is allocated, it returns null pointer pointing to that allocated memory location.
Calloc() initialized the allocated memory to zero	Malloc() doesn’t initializes the allocated memory. It contains garbage Values
It allocates multiple block of requested memory.	It allocates only single block of requested memory.

Why use malloc()

You can use malloc when you have to allocate objects which must exist beyond the execution of the memory block.
Malloc can be used if we need to allocate memory greater than size of stack.
Returns the pointer to the first byte of allocated space.
Enables developers to allocate memory as it is needed in the exact amount.
This function allocates memory block size bytes from the heap.

ptr = (cast_type *) malloc (byte_size);

In above syntax, ptr is a pointer of cast_type. Malloc function returns the pointer to the allocated memory of byte _size.

ptr = (int * ) malloc(50)

When this statement is executed, malloc reserves a memory space of 50 bytes. The address of the first byte reserved space is assigned to the pointer

When you have to set the allocated memory to 0.
You can use calloc() that returns a pointer to get access to memory heap.
Used when you need to initialize the elements to 0 to return a pointer to the memory.
To prevent overflow that is possible with malloc()
Use calloc() to request a page that is known to already be 0.

ptr = (cast_type *) calloc (n, size);

The above syntax is used to allocate n memory blocks of the same size. After the memory space is allocated, all the bytes are initialized to zero. The pointer, which is currently at the first byte of the allocated memory space, is returned.

Editor — Mon, 12 Jul 2021 19:45:16 +0000

Here malloc(), calloc(), realloc() are the memory allocation function. whereas free() is used to free the memory which is allocated by the above function.
so the free() is odd term.

The function malloc() reserves a block of memory of specified size and return a pointer of type void which can be casted into pointer of any form.
It allocates single block of memory

calloc() allocates multiple blocks of memory each of same size and sets all bytes to zero.
It allocates space for an array elements, initializes to zero and then returns a pointer to memory.

If suppose we assigned more or less memory than required, then we can change the size of the previously assigned memory space using realloc.

The function free is used to deallocate or free the memory after the program finishes which was dynamically allocated in the program.