Include <cstdlib> in header file but not main file?

Question

Hi all, I was practicing class earlier and I was stuck in compiling the program error. My program has a cstdlib function which is abs, but i include <cstdlib> in my main.cpp first and it shows error. It works when I put include <cstdlib> in the header file. Could someone explain this? Thanks!

Answer 1

If you expicitly use your function inside of "main" including cstdlib in main file should work. BUT if you create instance of your class in main, and then you call some method in which said "abs" is used, then you need to include library in this class file because linker will not know where to take function from during compilation.

Answer 2

Exactly Jakub Stasiak !
As a general rule include it where you use it.