std::feclearexcept

 

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通用的数值运算 Original: Generic numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

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浮点环境

功能 Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

feclearexcept （C++11）

fetestexcept （C++11）

feraiseexcept （C++11）

fegetexceptflag fesetexceptflag （C++11） （C++11）

fegetround fesetround （C++11） （C++11）

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宏常量 Original: Macro constants The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

FE_ALL_EXCEPT FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW FE_UNDERFLOW （C++11）

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Defined in header <cfenv>
int feclearexcept( int excepts );		（C++11 起）

尝试清除浮点异常中列出的位掩码参数excepts，这是一个按位或浮点例外宏的.

Original:

Attempts to clear the floating-point exceptions that are listed in the bitmask argument excepts, which is a bitwise OR of the 浮点例外宏.

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参数

excepts

-

位掩码列出的异常标志清除 Original: bitmask listing the exception flags to clear The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

返回值

​0​如果成功清除了所有指出的异常，或者如果excepts是零。在发生错误时，返回一个非零值.

Original:

​0​ if all indicated exceptions were successfully cleared or if excepts is zero. Returns a non-zero value on error.

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为例

#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

另请参阅

fetestexcept （C++11）	确定哪些指定浮点状态标志被设置 Original: determines which of the specified floating-point status flags are set The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数）