My son is about to start an introductory C programming module at Uni. Tuition will use a command line UNIX C (not C++) compiler.
He wants to practice during the summer break using either a Windows PC or a Mac, but with a C compiler that is fully compatible with standard C, as used on UNIX, so he doesn't get confused with non-standard syntax, compiler directives or libraries. This is a very basic course so something that lets him practice C language constructs without getting bogged down in other complexities is what he needs (provided it is compatible with standard C).
Can anyone recommend a good free compiler (command line, not GUI) and is he better off running it under Windows or on a Mac (which is, after all, UNIX under the skin).