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Asked: 2026-05-23T04:39:40+00:00

Possible Duplicates: checking for NULL before calling free What happens when you try to

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Possible Duplicates:
checking for NULL before calling free
What happens when you try to free() already freed memory in c?

Hope this isn’t a totally dumb question. Anyway…

What happens when a null pointer is passed to free.

Thank you!

P.S. What about a standard compliant allocator? Thanks again!

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1 Answer

  1. Editorial Team

    It immediately returns without doing anything.

    Per 7.20.3.2, paragraph 3:

    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.

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