What REALLY happens when you don't free after malloc?

Question

This has been something that has bothered me for ages now.

We are all taught in school (at least, I was) that you MUST free every pointer that is allocated. I\'m a

Answer 1

What's the real result here?

Your program leaked the memory. Depending on your OS, it may have been recovered.

Most modern desktop operating systems do recover leaked memory at process termination, making it sadly common to ignore the problem, as can be seen by many other answers here.)

But you are relying on a safety feature you should not rely upon, and your program (or function) might run on a system where this behaviour does result in a "hard" memory leak, next time.

You might be running in kernel mode, or on vintage / embedded operating systems which do not employ memory protection as a tradeoff. (MMUs take up die space, memory protection costs additional CPU cycles, and it is not too much to ask from a programmer to clean up after himself).

You can use and re-use memory any way you like, but make sure you deallocated all resources before exiting.