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  \ 
(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 floatingpoint exceptions. Each macro is only defined 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 floatingpoint exceptions are not supported by the implementation.
Constant  Explanation 
FE_DIVBYZERO

pole error occurred in an earlier floatingpoint operation 
FE_INEXACT

inexact result: rounding was necessary to store the result of an earlier floatingpoint operation 
FE_INVALID

domain error occurred in an earlier floatingpoint operation 
FE_OVERFLOW

the result of the earlier floatingpoint operation was too large to be representable 
FE_UNDERFLOW

the result of the earlier floatingpoint operation was subnormal with a loss of precision 
FE_ALL_EXCEPT

bitwise OR of all supported floatingpoint exceptions 
The implementation may define additional macro constants in <cfenv>
to identify additional floatingpoint exceptions. All such constants begin with FE_
followed by at least one uppercase letter.
See math_errhandling for further details.
[edit] Example
Run this code
#include <iostream> #include <cfenv> #include <cmath> #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 << "divsion 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"; } }
Output:
1.0/0.0 = inf division by zero reported 1.0/10 = 0.1 inexact result reported sqrt(1) = nan invalid result reported
[edit] See also
(C++11)(C++11)(C++11)

defines the error handling mechanism used by the common mathematical functions (macro constant) 
C documentation for floating point exception macros
