std::numeric_limits<double>::epsilon() undefined in Visual C++ 2015

Question

The following code produces an error: std::numeric_limits<double>::epsilon() undefined error.

Using numeric_limits<double>::epsilon also produces this error.

#ifndef _USE_MATH_DEFINES
#define _USE_MATH_DEFINES
#endif // !_USE_MATH_DEFINES

#include <math.h>
#include <limits.h>

class plusCartesianPoly {

public:

    static bool isClose(double a, double b)
    {
        if (fabs(a-b) <= std::numeric_limits::epsilon())
            return true;

        return(false);
    }
};

Answer 1

numeric_limits is declared in limits, not limits.h which is the C version of climits (by the way, math.h is the C version of cmath):

#ifndef _USE_MATH_DEFINES
#define _USE_MATH_DEFINES
#endif // !_USE_MATH_DEFINES

#include <cmath>
#include <limits>

class plusCartesianPoly {

public:

    static bool isClose(double a, double b)
    {
        if (std::fabs(a-b) <= std::numeric_limits<double>::epsilon())
            return true;

        return(false);
    }
};

Answer 2

<limits.h> contains the macro-type limits from the C standard library

You need <limits> to use the C++ standard library functions.