free (NULL) & delete NULL

7.20.3.2 The free function
Synopsis
1 #include
void free(void *ptr);
Description
2 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. Otherwise, if
the argument does not match a pointer earlier returned by the calloc, malloc, or
realloc function, or if the space has been deallocated by a call to free or realloc,
the behavior is undefined.
Returns
3 The free function returns no value.
ISO/IEC 9899:1999 (E)

5.3.5 Delete
If the operand has a class type, the operand is converted to a pointer type by calling the above-mentioned conversion function, and the converted operand is used in place of the original operand for the remainder of this section. In either alternative, if the value of the operand of delete is the null pointer the operation has no effect.
ISO/IEC 14882