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Question

VS 2015 for x86-32，虽然我从.NET 2003开始就看到了这个问题。

我想知道为什么没有解决这个问题：

#include <cfenv>
#include <cmath>

int main(int argc, char **argv)
{
    fesetround(FE_DOWNWARD);
    auto y_lo = sin(1.0); // y_lo = 0.84147098480789650
    fesetround(FE_UPWARD);
    auto y_hi = sin(1.0); // y_hi = (same)

    // y_hi SHOULD BE 0.84147098480789662

    return 0;
}

单步执行sin的dissasembly会显示它在执行fsin之前重置舍入模式（为什么？）。除了手工重写所有库函数外，可以采取哪些措施来解决这个问题呢？

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以下是cmp在[esp]检查已保存的控制字的有问题的call - 在此之前没有任何幻想，只有cmp word ptr [esp],27Fh ; WTF? Why force a default here?。

#include "stdafx.h"
    #include <iostream>
    #include <Windows.h>


    using namespace std;

    const int width = 12;
    const int height = 25;
    char bucket [width][height] ={"x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x"," "," "," "," "," "," "," "," "," "," ","x",
                                  "x","x","x","x","x","x","x","x","x","x","x","x",
    };
    void setCursorTo(int x, int y){
        HANDLE handle;
        COORD position;
        handle = GetStdHandle(STD_OUTPUT_HANDLE);
        position.X = x;
        position.Y = y;
        SetConsoleCursorPosition(handle, position);
    }


    int _tmain(int argc, _TCHAR* argv[])
    {

            setCursorTo(0,0);
            cout<<bucket<<endl;



        return 0;
    }enter code here

所以，AFAIK，这片小小的辉煌（或类似的东西）已经在CRT中恶化了至少12年。没人注意到这个吗？我无法找到或想象任何合理的理由背后。

fesetround不影响库函数

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