Is free() zeroing out memory?

Question

Until today I lived in belief that calling free() on memory space releases it for further allocation without any other modifications. Especially, considering th

Answer 1

There is another pitfall you might have not known actually, here:

free(pointer);

printf("After free(): %p \n", pointer); 

Even just reading the value of pointer after you free it is undefined behaviour, because the pointer becomes indeterminate.

Of course dereferencing the freed pointer - like in below example - is also not allowed:

free(pointer);

printf("After free(): %p, %d\n", pointer, *pointer);

ps. In general when printing address with %p (like in printf) cast it to (void*), e.g. (void*)pointer - otherwise you get undefined behaviour also