How to expand & stringify such macro?

Question

I'm making a wrapper for the string parser, which converts string to primitive types. I'm writing unit tests for it, so I need the string representation of the extreme values of these primitive types, so it is needed to stringify the standard macros such as INT_MIN and INT_MAX.

The normal stringify macros look like this:

#define STRINGIFY(content) #content
#define EXPAND_AND_STRINGIFY(input) STRINGIFY(input)

It works well for EXPAND_AND_STRINGIFY(SHRT_MAX), which will be expanded to "32767".

However, when it going to work with EXPAND_AND_STRINGIFY(SHRT_MIN), it will be expanded to "(-32767 -1)", because #define SHRT_MIN (-SHRT_MAX - 1). This is not what I want. Is there any possible workarounds for it?

Answer 1

No, there is no way to get a preprocessor macro to evaluate an arithmetic expression.

You can get the preprocessor to do arithmetic evaluate, but only in the context of #if, which allows you to evaluate a boolean expression. You can use that feature to rather laboriously output a number, but only by using preprocessor input in #included files, since you cannot put #if inside a macro.

You don't mention why you want to stringify INT_MIN, so I'm not in a position to offer an alternative, if indeed one exists.

However, it's most likely that your best bet is to simply produce the string at run-time, using snprintf.