CODEWITHSUNDEEP
c++gccc++11
tower120
tower120

Reputation: 5265

__STDC_VERSION__ not defined in C++11?

I tried to get __STDC_VERSION__ with gcc 4.8 and clang, but it just not defined. Compiler flags:

g++ -std=c++11 -O0 -Wall -Wextra -pedantic -pthread main.cpp && ./a.out

http://coliru.stacked-crooked.com/a/b650c0f2cb87f26d

#include <iostream>
#include <string>

int main()
{
    std::cout << __STDC_VERSION__  << std::endl;
}

As result:

main.cpp:6:18: error: '__STDC_VERSION__' was not declared in this scope

I have to include some header, or add compiler flags?

Upvotes: 5

Views: 8541

Answers (2)

quent
quent

Reputation: 2185

For those who come across the following warning:

warning: "__STDC_VERSION__" is not defined

This is due to the -Wundef flag which is enabled:

-Wundef

Warn if an undefined identifier is evaluated in an #if directive. Such identifiers are replaced with zero.

(from official GCC documentation)

So you can just define __STDC_VERSION__ to zero (-D__STDC_VERSION__=0) to suppress these warnings.

Upvotes: 2

nmaier
nmaier

Reputation: 33192

The official documentation states:

__STDC_VERSION__

...

This macro is not defined if the -traditional-cpp option is used, nor when compiling C++ or Objective-C.

Also, the C++ standard(s) leave it up to the implementation to define this macro or not, and g++ opted for the latter.

Depending on what you're trying to do the __cplusplus macro might be an alternative (it is not just defined, it has a value, too ;)

Upvotes: 5

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