相关疑难解决方法(0)

比较两个double或两个float值的最有效方法是什么？

简单地这样做是不正确的:

bool CompareDoubles1 (double A, double B)
{
   return A == B;
}

但是像这样:

bool CompareDoubles2 (double A, double B) 
{
   diff = A - B;
   return (diff < EPSILON) && (-diff < EPSILON);
}

似乎浪费处理.

有谁知道更聪明的浮动比较器？

我正在编写一个开始的C++类,我的书(从C++ Early Objects第7版开始)有一个非常糟糕的例子,说明如何检查浮点变量的值.

有问题的书籍例子(文件名pr4-04.cpp):

// This program demonstrates how to safely test a floating-point number
// to see if it is, for all practical purposes, equal to some value.
#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    double result = .666667 * 6.0; 

    // 2/3 of 6 should be 4 and, if you print result, 4 is displayed.
    cout << "result = " << result << endl;

    // However, internally result is NOT precisely equal to 4.
    // …