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FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW, FE_UNDERFLOW, FE_ALL_EXCEPT

From cppreference.com

Defined in header <cfenv>

#define FE_DIVBYZERO /*implementation defined power of 2*/

 (since C++11)

#define FE_INEXACT /*implementation defined power of 2*/

 (since C++11)

#define FE_INVALID /*implementation defined power of 2*/

 (since C++11)

#define FE_OVERFLOW /*implementation defined power of 2*/

 (since C++11)

#define FE_UNDERFLOW /*implementation defined power of 2*/

 (since C++11)

#define FE_ALL_EXCEPT FE_DIVBYZERO | FE_INEXACT | \ FE_INVALID | FE_OVERFLOW | \ FE_UNDERFLOW

 (since C++11)

All these macro constants (except FE_ALL_EXCEPT) expand to integer constant expressions that are distinct powers of 2, which uniquely identify all supported floating-point exceptions. Each macro is defined only if it is supported.

The macro constant FE_ALL_EXCEPT, which expands to the bitwise OR of all other FE_*, is always defined and is zero if floating-point exceptions are not supported by the implementation.

Constant Explanation
FE_DIVBYZERO pole error occurred in an earlier floating-point operation
FE_INEXACT inexact result: rounding was necessary to store the result of an earlier floating-point operation
FE_INVALID domain error occurred in an earlier floating-point operation
FE_OVERFLOW the result of the earlier floating-point operation was too large to be representable
FE_UNDERFLOW the result of the earlier floating-point operation was subnormal with a loss of precision
FE_ALL_EXCEPT bitwise OR of all supported floating-point exceptions

The implementation may define additional macro constants in <cfenv> to identify additional floating-point exceptions. All such constants begin with FE_ followed by at least one uppercase letter.

See math_errhandling for further details.

Example

#include <cfenv>
#include <cmath>
#include <iostream>

// #pragma STDC FENV_ACCESS ON

volatile double zero = 0.0; // volatile not needed where FENV_ACCESS is supported
volatile double one = 1.0;  // volatile not needed where FENV_ACCESS is supported

int main()
{
    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout <<  "1.0/0.0 = " << 1.0 / zero << '\n';
    if (std::fetestexcept(FE_DIVBYZERO))
        std::cout << "division by zero reported\n";
    else
        std::cout << "division by zero not reported\n";

    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "1.0/10 = " << one / 10 << '\n';
    if (std::fetestexcept(FE_INEXACT))
        std::cout << "inexact result reported\n";
    else
        std::cout << "inexact result not reported\n";

    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "sqrt(-1) = " << std::sqrt(-1) << '\n';
    if (std::fetestexcept(FE_INVALID))
        std::cout << "invalid result reported\n";
    else
        std::cout << "invalid result not reported\n";
}

Possible output: 

1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported

See also