How do I send a function to a function

I apologize for my ignorance on how to talk about this stuff but I haven't programmed for a few years and I've lost the lingo.

Anyway, I'm trying to write a function to estimate definite integrals and I don't know how to send a function to a function. Um... what I mean is, I want to write a function which will accept as one of its arguments any function of type double f (double x).

The best I can remember how to do this involves pointers and the address-of operator, but I've completely forgotten where to put the * or the &, or if I have to use the * operator multiple times.

If no one has any idea what I'm talking about, I'll try to explain myself better. Thanks in advance for any help.