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# std::feraiseexcept

From cppreference.com
< cpp‎ | numeric‎ | fenv

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.

### [edit] Parameters

excepts | - | bitmask listing the exception flags to raise

### [edit] Return value

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

### [edit] 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

### [edit] See also

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

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