Difference Between Malloc and Calloc | Calloc vs Malloc in C

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Difference Between Malloc and Calloc is that calloc allocates the memory and initializes every byte in the allocated memory to 0. In contrast, malloc allocates a memory block of a given size and doesn’t initialize the allocated memory. Malloc() and calloc() in the programming language C are the memory allocation done dynamically. Dynamic allocation is done during run time. Here we will discuss the difference between malloc() and calloc() allocation in detail.

Difference Between Malloc and Calloc PDF

Malloc() and calloc() are library routines that allocate or free up memory while running the program. Both malloc and calloc serve the purpose of dynamic memory allocation, but they differ in memory initialization and efficiency. Choosing the appropriate function depends on specific requirements and considerations. Let us find out the difference between malloc() and calloc() in the coming sections, along with malloc() and calloc() details.

Difference between Malloc and Calloc

There are several differences between malloc and calloc. Malloc() and calloc() in the programming language C are the memory allocation done dynamically. Dynamic allocation is done while run time. Malloc allocates a large block of memory with a specific size, whereas Calloc allocates a specific amount of memory.

The malloc() function and calloc() function differ according to the use of the function while assigning the memory while run time. The major differences between the two are explained in the table provided below:



This function only carries unuseful/garbage values

Carries important values.

Faster allocation time than calloc()

Slower allocation time wrt malloc().

Do not initialize the memory.

Initializes the memory.

Less secure than calloc()

Secure than malloc()

More time-efficient.

Less time efficient.

Returns the starting address.

It makes the return, along with making it zero.

Creates and assigns only a single block of memory

Can create or assign multiple memory blocks.

What is Malloc()?

The malloc stands for memory allocation. Malloc() is a type of library routine. There are four types of library routines. It is used to save the block of memory. The saving of the memory in malloc() occurs dynamically. The malloc will reserve the memory space in it as well.

The syntax of malloc() is: ptr = (cast_type *) malloc (byte_size);

The malloc function can be assigned to any pointer. The main function of the malloc() is that it returns the null pointer pointing to the memory location. It will be a type of void. Knowing about malloc() will help understand the difference between malloc() and calloc(). Check here the difference between function and procedure to understand the functions properly.

What is Calloc()?

The calloc() is another type of library routine. It stands for contiguous allocation. It is also used for memory allocation. The calloc is used where memory allocation is required in complex data structures. Calloc() returns the null pointer on failing to allocate the specific space.

The syntax of calloc() is: ptr = (cast_type *) calloc (n, size);

Compatibility and Portability of malloc() and calloc()

When considering compatibility and portability, both malloc and calloc are widely supported and available in most standard C programming environments. They are part of the C standard library and are portable across different operating systems and platforms.

Compatibility: Both malloc and calloc are compatible with various C compilers and development environments. They adhere to the C language standards, making them compatible with a wide range of systems and compilers, including Windows, macOS, Linux, and others.

Portability: The portability of malloc and calloc refers to their ability to function consistently across different platforms and architectures. These functions have been implemented to ensure portability, allowing developers to write code that can be compiled and executed on different systems without major modifications.

Summary: Choosing Between malloc() and calloc()

Choosing between malloc and calloc depends on specific requirements and considerations.

malloc is suitable when dynamic memory allocation is needed without the requirement for initializing memory to zero. It offers flexibility in allocating memory blocks of a specified size.

On the other hand, calloc is preferable when initializing memory to zero is desired. It automatically sets allocated memory to zero, which can be useful for arrays or structures where initialization is necessary.

Consider factors such as memory efficiency, performance, error handling, and compatibility with existing code when making a decision. Evaluating the specific needs and trade-offs of each function will help determine the appropriate choice for a given scenario.

Conclusion: Malloc vs Calloc

There are four types of libraries to allocate memory and free it up during the program execution. They are routines, calloc(), free(), realloc(), and malloc(). All of them are different from each other. The comparison of malloc vs. calloc is given below.

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  • It reserves memory space of a specified size.
  • It is used to allocate objects which must exist beyond the execution of the current memory block.
  • In this, developers can allocate memory as per the requirement.

Calloc ()

  • It initializes the elements to zero to return a pointer to the memory.
  • It is used to request a page known to already be zeroed.
  • All the bytes are initialized to zero after the memory space is allocated.
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