compilation error using constexpr in C++

Question

I'm trying to use constexpr in C++ but get the compile error: 'constexpr' was not declared in this scope.

I tried both in CodeBlocks using the GNU GCC compiler, and in Visual Studio 2013.

the code is:

#include <iostream>

int main()
{
    constexpr double ft2m = 0.3048;
    std::cout << ft2m;
}

What could be the problem?

Also, [partial duplicate here](http://stackoverflow.com/q/20264644/440558) (regarding VS2013). — Some programmer dude, Mar 06 '17 at 07:54
I'm going guess that you need to change your compiler settings so that it compiles against the C++11 standard. — R Sahu, Mar 06 '17 at 07:55

score 2 · Answer 1 · answered Mar 06 '17 at 07:54

2

What version of gcc are you using?

You might need at -std=c++11 to your command line

answered Mar 06 '17 at 07:54

qianfg

score 2 · Answer 2 · answered Mar 06 '17 at 07:55

The problem is that MSVC2013 does not support constexpr. It does not purport to implement the C++11 standard.

The first version that does is MSVC2015.

Your constexpr statement is grammatically correct C++11. Make sure you have a GCC version compliant with that standard.

2 Answers2