What functions are used for dynamic memory allocation in C language?

C Programming Language >   Dynamic Memory Allocation >   Introduction to DMA  

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Answer:

malloc()

• The malloc() function is used to allocate the memory during the execution of the program.
• It does not initialize the memory but carries the garbage value.
• It returns a null pointer if it could not be able to allocate the requested space.

Syntax

ptr = (cast-type*) malloc(byte-size) // allocating the memory using malloc() function.  

calloc()

• The calloc() is same as malloc() function, but the difference only is that it initializes the memory with zero value.

Syntax

ptr = (cast-type*)calloc(n, element-size);// allocating the memory using calloc() function. 

realloc()

• The realloc() function is used to reallocate the memory to the new size.
• If sufficient space is not available in the memory, then the new block is allocated to accommodate the existing data.

Syntax

ptr = realloc(ptr, newsize); // updating the memory size using realloc() function.  

In the above syntax, ptr is allocated to a new size.

free()

The free() function releases the memory allocated by either calloc() or malloc() function.

Syntax

free(ptr); // memory is released using free() function.  

The above syntax releases the memory from a pointer variable ptr.

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