| Defined in header <cfenv> | ||
|---|---|---|
int fetestexcept( int excepts ); | (since C++11) |
Determines which of the specified subset of the floating point exceptions 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
#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
See also
| (C++11) | clears the specified floating-point status flags (function) |
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