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std::feclearexcept

来自 cppreference.com
< cpp‎ | numeric‎ | fenv
 
 
 
浮点环境
函数
feclearexcept
(C++11)
(C++11)(C++11)
(C++11)(C++11)
宏常量
(C++11)
 
定义在头文件 <cfenv>
int feclearexcept( int excepts );
(自 C++11)

尝试清除在位掩码参数 excepts 中列出的浮点异常,该参数是 浮点异常宏 的按位 OR。

内容

[编辑] 参数

excepts - 列出要清除的异常标志的位掩码

[编辑] 返回值

0 如果成功清除了所有指示的异常,或者 excepts 为零。如果出错,则返回非零值。

[编辑] 示例

#include <cfenv>
#include <cmath>
#include <iostream>
 
// #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 << "division 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";
}

可能的输出

1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported

[编辑] 另请参阅

确定哪些指定的浮点状态标志被设置
(函数) [编辑]
C 文档 针对 feclearexcept