How can such a macro be expanded and strengthened?
I am creating a wrapper for a string parser that converts a string to primitive types. I'm writing unit tests for it, so I need a string representation of the extreme values of these primitive types, so standard macros like INT_MIN and INT_MAX need to be rolled up.
Normal string macros look like this:
#define STRINGIFY(content) #content
#define EXPAND_AND_STRINGIFY(input) STRINGIFY(input)
It works well for EXPAND_AND_STRINGIFY(SHRT_MAX)
to be expanded to "32767".
However, when it works 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. Are there possible workarounds?
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No, there is no way to get a preprocessor macro to evaluate an arithmetic expression.
You can force the preprocessor to do arithmetic evaluation, but only in a context #if
that allows you to evaluate a boolean expression. You can use this function for a rather tedious output of a number, but only using preprocessor input in the #include
d files , as you cannot put #if
inside a macro.
You don't mention why you want to shrink INT_MIN
, so I can't suggest an alternative if one actually exists.
However, most likely your best bet is to simply create the string at runtime using snprintf
.
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