What is the difference between malloc() and calloc()

Improve Article. Like Article. Previous How to deallocate memory without using free in C? Next Dynamic Memory Allocation in C using malloc , calloc , free and realloc. Recommended Articles. What is the difference between single quoted and double quoted declaration of char array? Article Contributed By :. This presents a risk. Speed of execution: calloc is a tiny bit slower than malloc because of the extra step of initializing the memory region allocated.

However, in practice the difference in speed is very small and can be ignored. There are two major differences between malloc and calloc in C programming language: first, in the number of arguments.

The malloc takes a single argument, while calloc takess two. Second, malloc does not initialize the memory allocated, while calloc initializes the allocated memory to ZERO. Both malloc and calloc are used in C language for dynamic memory allocation they obtain blocks of memory dynamically. Dynamic memory allocation is a unique feature of C language that enables us to create data types and structures of any size and length suitable to our programs. Following are the major differences and similarities between malloc and calloc in detail with their syntax and example usage.

Vipin 01 Jul The following are the differences between malloc and calloc : - Byte of memory is allocated by malloc , whereas block of memory is allocated by calloc. Medishetti 30 Jun Both are the built in functions stdlib Both are used to create the memory dynamically from heap segment during runtime. Vaibhav 28 Jun Well,Calloc and Malloc both are library functions which are used to allocate memory dynamically.

Calloc stands for clear allocation of memory while malloc stands for memory allocation. It is the efficient method to deal with memory. It is used generally in case of linked list where we create memory dynamically.

Now ,coming to the real question differences between these two:-well,1 in case of malloc we have only one argument,while in case of calloc we have two arguments. Rishabh 05 Jan Malloc :- 1 The name malloc stands for memory allocation. Calloc :- 1 The name calloc stands for contiguous allocation. Other Related Discussions. Regarding for Data Structure. They are used for obtaining and dynamically allocating memory blocks. The pointer returned by both malloc or calloc has proper alignment with regards to the object in the reckoning.

However, they must first be cast into appropriate types for the process to be successful. By proper alignment, we mean that the value assigned to the returned address will be guaranteed to figure as an even multiple of alignment. Here, the value attributed to the alignment should be a power of two; also, it must either be equal to or greater than the size of a given the word.

Yet another similarity is that the calloc and malloc functions will fail to be successful in the following cases:. If the physical limits defined for the system is exceeded by n memory bytes that cannot be assigned. If adequate memory is not available for the allocation of n bytes of system memory; it becomes possible for the application to try again later.

Dynamic memory allocation is an essential and unique feature attributed to C language. It enables programmers to create data structures and types of different sizes and lengths as is suited to the program in the reckoning. Memory allocation relates to the assigning of computer memory to enable the execution of processes and applications.

Dynamic allocation techniques are generally used when the coders are not aware of the amount of memory space that will be required for the running of any program and process. Dynamic memory allocation in C language is attributed to the issues linked with static memory assigning.

The reason being that if fewer elements are attached to the memory and saved within the same, then the rest of the allocated memory would go to waste. Therefore, C dynamic memory allocation declarations are used to overcoming the issues of static memory allocation.

Herein, the memory is assigned as and when required and not earlier on. Both these functions in C language - malloc and calloc — are useful for the dynamic allocation of memory space. They have quite a few differences and similarities between them. Additionally, their benefits and disadvantages can be gauged to assess which function would suit a particular C program or process.

For instance, malloc is faster in comparison to calloc. More so, malloc is much easier to put into use as it merely requires one argument.

Calloc takes more time as it first initialises the memory space to ZERO and allocates the required memory to the same. The decision to use calloc or malloc would depend on the need for variable initialisation and how important it is for the performance of your program — take your pick accordingly. Consider the following example below:. If you consider calloc syntax, it will take 2 arguments.

Number of blocks: malloc assigns single block of requested memory, calloc assigns multiple blocks of the requested memory. Initialization: malloc - doesn't clear and initialize the allocated memory. Speed: malloc is fast. Manner of memory Allocation: The malloc function assigns memory of the desired 'size' from the available heap.

Meaning on name: The name malloc means "memory allocation". The name calloc means "contiguous allocation". Behavior: malloc allocates a memory block, without initializing it, and reading the contents from this block will result in garbage values. Syntax: malloc takes 1 argument the size to be allocated , and calloc takes two arguments number of blocks to be allocated and size of each block.

The return value from both is a pointer to the allocated block of memory, if successful. Otherwise, NULL will be returned indicating the memory allocation failure. The same functionality as calloc can be achieved using malloc and memset :. Note that malloc is preferably used over calloc since it's faster. If zero-initializing the values is wanted, use calloc instead. This ability is not often used in many platforms with linear addressing. Now if such a system can supply such a large allocation is another matter.

Most today will not. Both malloc and calloc allocate memory, but calloc initialises all the bits to zero whereas malloc doesn't. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Difference between malloc and calloc? Ask Question. Asked 12 years, 1 month ago.

Active 1 year, 1 month ago. Viewed k times. Improve this question. Mat k 39 39 gold badges silver badges bronze badges. In C you don't cast the result of malloc family — phuclv. Nathaniel J. Add a comment. Active Oldest Votes. Improve this answer. Jarvis 8, 3 3 gold badges 23 23 silver badges 53 53 bronze badges.

Fred Larson Fred Larson Use malloc if you are going to set everything that you use in the allocated space. Use calloc if you're going to leave parts of the data uninitialized - and it would be beneficial to have the unset parts zeroed.