What is dynamic memory allocation? Mention four functions used for dynamic memory manipulation.

 

DOEACC

[M3-R4: PROGRAMMING AND PROBLEM SOLVING THROUGH ‘C’ LANGUAGE]

[ July, 2010 (New)]

 

Q. What is dynamic memory allocation? Mention four functions used for dynamic memory manipulation. 

Answer: Dynamic memory allocation in programming refers to the process of allocating memory at runtime (during program execution) rather than at compile time. This allows programs to allocate memory as needed and release it when it's no longer required. Dynamic memory allocation is particularly useful when the size of data structures is not known at compile time or when memory needs to be managed more flexibly.

Four functions commonly used for dynamic memory manipulation in C are:

malloc() (Memory Allocation):

Prototype: void* malloc(size_t size);
Description: Allocates a specified number of bytes of memory. It returns a pointer to the beginning of the allocated memory block.
calloc() (Contiguous Allocation):

Prototype: void* calloc(size_t num, size_t size);
Description: Allocates a block of memory for an array of elements, each of a specified size. It initializes all bytes in the allocated memory to zero.
realloc() (Reallocate Memory):

Prototype: void* realloc(void* ptr, size_t size);
Description: Changes the size of the previously allocated memory block. It can be used to resize a previously allocated memory block, either increasing or decreasing its size.
free() (Free Memory):

Prototype: void free(void* ptr);
Description: Releases the memory block pointed to by the given pointer. It deallocates the memory previously allocated by malloc, calloc, or realloc.
Here's a brief explanation of each function:

malloc: Allocates a specified amount of memory, but the initial content is undefined.

calloc: Allocates a specified number of blocks of memory, each with a specified size. It initializes the memory to zero.

realloc: Changes the size of the allocated memory block. It can be used to resize or reallocate memory.

free: Releases the allocated memory, making it available for other uses.

It's important to use these functions carefully to avoid memory leaks or accessing memory that has been freed. Additionally, in C++, the new and delete operators are often used for dynamic memory allocation and deallocation.