Subj : Re: Htick Hatching
To   : Michael Dukelsky
From : Wilfred van Velzen
Date : Fri Mar 12 2021 13:52:18

Hi Michael,

On 2021-03-12 15:30:48, you wrote to me:

 ac>>> #define nfree(a) {if(a != NULL) {free(a); a = NULL;}}

 WV>> And the test for NULL isn't necessary, because free() is by definition
 WV>> doing nothing if the pointer passed to it is NULL.

 MD> Yes, I know it. It was written long ago and not by me and I do not change
 MD> it because I do not know whether free() always worked as it works now or it
 MD> did not test the pointer for NULL in some ancient systems.

The Second Edition (1988) of The C Programming Language by Kernighan & Ritchie (describes C as defined by the ANSI standard), already describes it as follows:

void free(void *p)
  free deallocates the space pointed to by p; it does nothing if p is NULL. p must be a pointer to space previously allocated by calloc, malloc, or realloc.

So I think you are save to assume it "always" worked that way! ;)

Bye, Wilfred.

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