std::feraiseexcept

C++

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Concepts library (C++20)

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Technical Specifications

Numerics library

Common mathematical functions

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Floating-point environment (C++11)

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Compile-time rational arithmetic (C++11)

Numeric algorithms

gcd (C++17)

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iota (C++11)

accumulate

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reduce (C++17)

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bit_cast (C++20)

ispow2 (C++20)

ceil2 (C++20)

floor2 (C++20)

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Floating-point environment

Functions

feclearexcept (C++11)

fetestexcept (C++11)

feraiseexcept (C++11)

fegetexceptflagfesetexceptflag (C++11)(C++11)

fegetroundfesetround (C++11)(C++11)

fegetenvfesetenv (C++11)

feholdexcept (C++11)

feupdateenv (C++11)

Macro constants

FE_ALL_EXCEPTFE_DIVBYZEROFE_INEXACTFE_INVALIDFE_OVERFLOWFE_UNDERFLOW (C++11)

FE_DOWNWARDFE_TONEARESTFE_TOWARDZEROFE_UPWARD (C++11)

FE_DFL_ENV (C++11)

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

Attempts to raise all floating point exceptions listed in excepts (a bitwise OR of the floating point exception macros). If one of the exceptions is FE_OVERFLOW or FE_UNDERFLOW, this function may additionally raise FE_INEXACT. The order in which the exceptions are raised is unspecified, except that FE_OVERFLOW and FE_UNDERFLOW are always raised before FE_INEXACT.

Parameters

excepts

-

bitmask listing the exception flags to raise

Return value

0 if all listed exceptions were raised, non-zero value otherwise.

Example

Run this code

#include <iostream>
#include <cfenv>

#pragma STDC FENV_ACCESS ON

int main()
{
    std::feclearexcept(FE_ALL_EXCEPT);
    int r = std::feraiseexcept(FE_UNDERFLOW | FE_DIVBYZERO);
    std::cout <<  "Raising divbyzero and underflow simultaneously "
              << (r?"fails":"succeeds") << " and results in\n";
    int e = std::fetestexcept(FE_ALL_EXCEPT);
    if (e & FE_DIVBYZERO) {
        std::cout << "division by zero\n";
    }
    if (e & FE_INEXACT) {
        std::cout << "inexact\n";
    }
    if (e & FE_INVALID) {
        std::cout << "invalid\n";
    }
    if (e & FE_UNDERFLOW) {
        std::cout << "underflow\n";
    }
    if (e & FE_OVERFLOW) {
        std::cout << "overflow\n";
    }
}

Output:

Raising divbyzero and underflow simultaneously succeeds and results in
division by zero
underflow

See also

feclearexcept (C++11)	clears the specified floating-point status flags (function)
fetestexcept (C++11)	determines which of the specified floating-point status flags are set (function)