Is there a way to do check for numerical equality in macros?
I want to do something like
#define choice 3
#if choice == 3
....
#endif
#if choice == 4
...
#endif
Does C macros have support for things like this?
C macro: #if check for equality
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3 Answers
Another way to write your code uses chained #elif directives:
#if choice == 3
...
#elif choice == 4
...
#else
#error Unsupported choice setting
#endif
Note that if choice is not #defined, the compiler (preprocessor) treats it as having the value 0.
Indeed that should work. See http://gcc.gnu.org/onlinedocs/cpp/If.html#If
That reference is accurate, but written in "standards format": abstractly without examples.
As far as i know that should work. What compiler are you using ?
PS : Just for information, the defines names are usually written in caps !
#define CHOICE 3
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