Under what circumstances can malloc return NULL?

Question

It has never happened to me, and I\'ve programming for years now.

Can someone give me an example of a non-trivial program in which malloc will actually

Answer 1

Any program at all written in c that needs to dynamically allocate more memory than the OS currently allows.

For fun, if you are using ubuntu type in

 ulimit -v 5000

Any program you run will most likely crash (due to a malloc failure) as you've limited the amount of available memory to any one process to a pithy amount.