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std::fetestexcept(3)	       C++ Standard Libary	    std::fetestexcept(3)

NAME
     std::fetestexcept - std::fetestexcept

Synopsis
	Defined in header <cfenv>
	int fetestexcept( int excepts );  (since C++11)

	Determines  which  of  the specified subset of the floating point excep-
     tions are
	currently set. The argument excepts is a  bitwise  OR  of  the	floating
     point exception
	macros.

Parameters
	excepts - bitmask listing the exception flags to test

Return value
	Bitwise OR of the floating-point exception macros that are both included
     in excepts
	and correspond to floating-point exceptions currently set.

Example
     // Run this code

      #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
	feclearexcept clears the specified floating-point status flags
	(C++11)       (function)
	C documentation for
	fetestexcept

http://cppreference.com 	   2024.06.10		    std::fetestexcept(3)
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