My question is why i have to assign NULL to pointer after freeing allocated memory?
free(*ptr);
*ptr = NULL;
I mean situation like this, why it is necesssary?
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1Not doing it would make your pointer reference a deallocated chunk of memory, meaning you would have a dandling pointer, which is really dangerous. – imperosol Mar 31 '22 at 07:40
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1It also means you can `free` it again without harm, because `free(NULL)` does nothing. – Weather Vane Mar 31 '22 at 07:46
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1I assume you actually meant `ptr=NULL;`. What you wrote means that you access `*ptr` after the memory was free which is illega.l. – Gerhardh Mar 31 '22 at 10:06
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1It's not necessary. It's useful. Sort of. – user253751 Mar 31 '22 at 10:11