Answer 1

malloc:
Parameters: Int, size of memory in bytes
Returns: void *, pointer to void , need to be type casted into valid pointer for proper pointer arithmetic.
calloc:
Parameters:
Int, size of each block in bytes, and
Int, total number of blocks.
Returns: same as malloc
Example:
int *arr = (int *)malloc(ELEMENT_COUNT * sizeof(int));
Read more : https://www.google.com/amp/s/www.geeksforgeeks.org/dynamic-memory-allocation-in-c-using-malloc-calloc-free-and-realloc/amp/