二元运算符的参数之一必须是包含类型 c#

Question

public static int[,] operator *(int[,] arr1, int[,] arr2)
    {
        int sum;
        int[,] res = new int[arr1.GetLength(0), arr2.GetLength(1)];
        for (int i = 0; i < arr1.GetLength(0); i++)
        {
            for (int j = 0; j < arr2.GetLength(1); j++)
            {
                sum = 0;
                for (int k = 0; k < arr1.GetLength(1); k++)
                {
                    sum = sum + (arr1[i, k] * arr2[k, j]);
                }
                res[i, j] = sum;
                //Console.Write("{0} ", res[i, j]);
            }
            //Console.WriteLine();
        }

        return res;
    }

这里我试图重载 * 运算符来将两个矩阵相乘.. 但编译器不断向我显示错误...

" 二元运算符的参数之一必须是包含类型 c#"

请告诉我我的代码中有什么问题以及如何解决它..

Answer 1

编译器已经告诉您哪里出了问题 - 但引用 C# 5 规范的第 7.3.2 节：

User-defined operator declarations always require at least one of the parameters to be of the class or struct type that contains the operator declaration. Thus, it is not possible for a user-defined operator to have the same signature as a predefined operator.

换句话说，如果有：

class Foo
{
    public static int[,] operator *(int[,] arr1, Foo arr2)
    {
        ...
    }
}

... 因为第二个操作数是声明类型。但在你的情况下，两个操作数都是 int[,].

您可以做的是添加一个扩展方法：

public static class ArrayExtensions
{
    public static int[,] Times(this int[,] arr1, int[,] arr2)
    {
        ...
    }
}

那么你可以：

int[,] x = ...;
int[,] y = ...;
int[,] z = x.Times(y);

另一种解决方案 - 更好的解决方案，IMO，将声明您自己的 Matrix class 来封装矩阵运算。然后你可以定义你自己的乘法运算符：

public static Matrix operator *(Matrix left, Matrix right)

...而且您不会干扰 int[,] 不打算被视为矩阵的数组。

二元运算符的参数之一必须是包含类型 c#

one of the parameters of a binary operator must be the containing type c#

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visual-studio-2010

visual-c#-express-2010