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C.3.4 Preprocessor Arithmetic

In C99 and later, preprocessor arithmetic, used for #if expressions, must be evaluated as if all signed values are of type intmax_t and all unsigned values of type uintmax_t. Many compilers are buggy in this area, though. For example, as of 2007, Sun C mishandles #if LLONG_MIN < 0 on a platform with 32-bit long int and 64-bit long long int. Also, some older preprocessors mishandle constants ending in LL. To work around these problems, you can compute the value of expressions like LONG_MAX < LLONG_MAX at configure-time rather than at #if-time.