Thread: free-ing un-malloc-ed memory

Originally Posted by bithub

You can call realloc() on a NULL pointer.

I agree, of course you can. You have to be able to allocate pointer for NULL pointers, because of the simple concept of the "initialize your variables before you attempt to use them" mantra.

All a NULL pointer is is a variable whose value has been set to nothing. It's like initializing an int to 0 first.

Quzah.

Originally Posted by laserlight

Unless a mistake is made for the same reason as you cite NULL being useful. The reader would then be misinformed unless he/she checked, but if he/she checked then the use of NULL would no longer be useful.

6 in one, half a dozen in the other...
Both ways have advantages & disadvantages.
I would assume that if someone did find a discrepancy as you mentioned, they would fix it so the next reader doesn't have to go through the same head scratching motion. In 10 years I've never seen anyone try to assign NULL to a non-pointer. So I would say it's an extremely remote possibility.

Originally Posted by cpjust

6 in one, half a dozen in the other...
Both ways have advantages & disadvantages.

That's right, which is why I think it boils down to personal choice. In C++ we can wait for nullptr, but I am afraid there is no good solution coming up for C.

Originally Posted by cpjust

In 10 years I've never seen anyone try to assign NULL to a non-pointer.

I have done it myself when using some of those crazy programming interfaces with an excessive number of parameters, some of which are pointers while others are not. It is arguably a problem with the interface, but in such cases it does not matter whether the reader sees a NULL or a 0: he/she has to double check anyway.