Accepted answer
Score: 49

__STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS are a workaround to allow C++ programs 9 to use stdint.h macros specified in the C99 standard 8 that aren't in the C++ standard. The macros, such 7 as UINT8_MAX, INT64_MIN, and INT32_C() may be defined already in C++ applications 6 in other ways. To allow the user to decide 5 if they want the macros defined as C99 does, many 4 implementations require that __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS be defined 3 before stdint.h is included.

This isn't part of the 2 C++ standard, but it has been adopted by 1 more than one implementation.

Score: 7

The above issue has vanished. C99 is an 4 old standard, so this has been explicitly 3 overruled in the C++11 standard, and as 2 a consequence C11 has removed this rule.

More 1 details there:

Score: 4

In stdint.h under C++, they control whether to define 2 macros like INT32_MAX or INT32_C(v). See your platform's stdint.h for 1 additional information.

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