c - 在实际指针的副本上使用 free() 是可以接受/正确的吗？

Question

这是:

int *a = malloc (sizeof (int) );
int *b = a;
free (b);

与此相同:

int *a = malloc (sizeof (int) );
free (a);

如果是，则无需解释，但如果不是，请详细说明原因!

Answer 1

是的，它们是等价的。

引用 C11，第 §7.22.3.3 章，(强调我的)

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 a memory management function, or if the space has been deallocated by a call to free or realloc, the behavior is undefined.

因此，只要您传递先前由 malloc() 或系列返回的相同 ptr 值(指针本身或其副本)，您就可以一切顺利。