Question

＆gt; = method：

的比较有问题

public static bool operator >=(Fraction left, Fraction right)
     {
         return left.CompareTo(right) >= 0;
     }

它似乎不起作用？！

例如：

25＆gt; = 6/5返回FALSE

任何人都可以对此有所了解吗？

以下是请求的代码。我希望有人能发现它有什么问题。

    /// <summary>
    /// Compares an object to this Fraction
    /// </summary>
    /// <param name="obj">The object to compare against (null is less than everything)</param>
    /// <returns>-1 if this is less than <paramref name="obj"></paramref>,
    ///  0 if they are equal,
    ///  1 if this is greater than <paramref name="obj"></paramref></returns>
    /// <remarks>Will convert an object from longs, doubles, and strings as this is a value-type.</remarks>
    public int CompareTo(object obj)
    {
        if (obj == null)
            return 1;   // null is less than anything

        Fraction right;

        if (obj is Fraction)
            right = (Fraction)obj;
        else if (obj is long)
            right = (long)obj;
        else if (obj is double)
            right = (double)obj;
        else if (obj is string)
            right = (string)obj;
        else
            throw new ArgumentException("Must be convertible to Fraction", "obj");

        return this.CompareTo(right);
    }

    /// <summary>
    /// Compares this Fraction to another Fraction
    /// </summary>
    /// <param name="right">The Fraction to compare against</param>
    /// <returns>-1 if this is less than <paramref name="right"></paramref>,
    ///  0 if they are equal,
    ///  1 if this is greater than <paramref name="right"></paramref></returns>
    public int CompareTo(Fraction right)
    {
        // if left is an indeterminate, punt to the helper...
        if (this.m_Denominator == 0)
        {
            return IndeterminantCompare(NormalizeIndeterminate(this.m_Numerator), right);
        }

        // if right is an indeterminate, punt to the helper...
        if (right.m_Denominator == 0)
        {
            // note sign-flip...
            return -IndeterminantCompare(NormalizeIndeterminate(right.m_Numerator), this);
        }

        // they're both normal Fractions
        CrossReducePair(ref this, ref right);

        try
        {
            checked
            {
                long leftScale = this.m_Numerator * right.m_Denominator;
                long rightScale = this.m_Denominator * right.m_Numerator;

                if (leftScale < rightScale)
                    return -1;
                else if (leftScale > rightScale)
                    return 1;
                else
                    return 0;
            }
        }
        catch (Exception e)
        {
            throw new FractionException(string.Format("CompareTo({0}, {1}) error", this, right), e);
        }
    }


    /// <summary>
    /// Cross-reduces a pair of Fractions so that we have the best GCD-reduced values for multiplication
    /// </summary>
    /// <param name="frac1">The first Fraction [WILL BE MODIFIED IN PLACE]</param>
    /// <param name="frac2">The second Fraction [WILL BE MODIFIED IN PLACE]</param>
    /// <remarks>Modifies the input arguments in-place!</remarks>
    /// <example>(3/4, 5/9) = (1/4, 5/3)</example>
    public static void CrossReducePair(ref Fraction frac1, ref Fraction frac2)
    {
        // leave the indeterminates alone!
        if (frac1.m_Denominator == 0 || frac2.m_Denominator == 0)
            return;

        long gcdTop = GCD(frac1.m_Numerator, frac2.m_Denominator);
        frac1.m_Numerator = frac1.m_Numerator / gcdTop;
        frac2.m_Denominator = frac2.m_Denominator / gcdTop;

        long gcdBottom = GCD(frac1.m_Denominator, frac2.m_Numerator);
        frac2.m_Numerator = frac2.m_Numerator / gcdBottom;
        frac1.m_Denominator = frac1.m_Denominator / gcdBottom;
    }

Answer 1

CrossReducePair更改数字之间的关系。你的（3 / 4,5 / 9）=（1 / 4,5 / 3）的例子非常明显。如果你成倍增加交叉减少是有意义的，但如果你只是比较它们就没有。

Answer 2

CrossReducePair方法似乎没有多大意义。如评论中所述，它会将(3/4, 5/9)转换为(1/4, 5/3)。注意：3/4 > 5/9，但1/4 < 5/3。

此外，使用CompareTo方法修改对象是一个非常糟糕的主意。

C＃中的分数比较问题

2 个答案: