Is there any danger in allocating memory with realloc using the
initially NULL-valued ptr
If ptr is a null pointer, the realloc function behaves like the malloc
function for the speciﬁed size.
For the second part:
int* ptr; // no value given to ptr
would it be a problem to call realloc using ptr?
If you’re using uninitialized pointers then that is a very serious problem indeed since you can’t predict what their value will be. The function
realloc only works correctly for
NULL or values obtained from
Otherwise, if ptr does not match a pointer earlier returned by a
memory management function […] the behavior is undeﬁned