Question

what is malloc calloc realloc and free

Answer 1

methods used for manipulating memory.

Answer 2

These functions, as eSpeX said, are functions in the C/C++ standard library that are used for the allocation of memory.

Malloc 'alloc'ates a specific number of bytes, calloc allocates the number of bytes you called and initializes them at zero, realloc can increase (or decrease) the size of block of memory, and free will release the specified block of memory