Example of something which is, and is not, a “Constant Expression” in C?

Question

I\'m a tad confused between what is and is not a Constant Expression in C, even after much Googleing. Could you provide an example of something which is, and which is not, a

Answer 1

Another fun little wrinkle: in C, the value of an 'enum' is a constant, but may only be used after the declaration of the 'enum' is complete. The following, for example, is not acceptable in standard C, though it is acceptable in C++:

enum {foo=19, bar, boz=bar+5;};

It could be rewritten:

enum {foo=19, bar}; enum {boz=bar+5;};

though this would end up defining multiple different enumeration types, rather than one which holds all the values.