free function in c code example

Example 1: free in c

the C library function void free(void *ptr) 
  deallocates the memory previously allocated by a call to calloc, malloc, or realloc.

Example 2: c malloc array

#define ARR_LENGTH 2097152
int *arr = malloc (ARR_LENGTH * sizeof *arr);

Example 3: what is the use of malloc in c

In C, the library function malloc is used to allocate a block of memory on the heap. The program accesses this block of memory via a pointer that malloc returns. When the memory is no longer needed, the pointer is passed to free which deallocates the memory so that it can be used for other purposes.