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std::fetestexcept

Defined in header <cfenv>

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int fetestexcept( int excepts );

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(since C++11)

确定当前设置了浮点异常的哪个指定子集。争论excepts是按位或按位计算的。浮点异常宏...

参数

excepts

-

bitmask listing the exception flags to test

返回值

中包含的浮点异常宏的位或。excepts并对应于当前设置的浮点异常。

二次

代码语言:javascript
复制
#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";
    }
}

二次

产出:

二次

代码语言:javascript
复制
1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported

二次

另见

feclearexcept (C++11)

clears the specified floating-point status flags (function)

代码语言:txt
复制
 ? cppreference.com

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