In C this became possible after C89, code is cleaner.
C89: 4.10.3.2 The free function.
The free function causes the space pointed to by ptr to be deallocated, that is, made available for further allocation. If ptr is a null pointer, no action occurs.
More info: https://stackoverflow.com/questions/13818803/check-for-null-before-delete-in-c-good-practice
In C this became possible after C89, code is cleaner.