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Function Free() in C doesn't work

I just asked a question about free(), check the link below. If I can’t use if(pointer != NULL), then what can I use, just in case it doesn’t work because of a stupid mistake I made.

Function free() in C isn't working for me

Answer 1

Whenever you free a pointer you should set it to null – then you can use your test safetly

free(pointer);
pointer=NULL;

if(!pointer)
{
    pointer=malloc(42);
}

You could even create your own free function so you dont forget to set to null.

void myfree(void **ptr)
{
    free(*ptr);
    *ptr=NULL;
}