问题代码：
class Program
    {
        static void Main(string[] args)
        {
            Program myClass1 = new Program();
            int[,] arrayA = new int[2, 3];
            int[,] arrayB = new int[3, 2];

            for (int i = 0; i < 2; i++ )
            {
                for (int j = 0; j < 3; j++ )
                {
                    arrayA[2, 3] = i + j + 10;
                }
            }

            Console.WriteLine("以下输出矩阵arrayA结构！！");
            myClass1.为什么这里调不出printfArray()方法呢？
        }
    }
课本源码：

class Matrixm
{
    static void Main()
    {
        Matrixm myClass1 = new Matrixm();
        int[,] arrayA = new int[2, 3];
        int[,] arrayB = new int[3, 2];

        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 3; j++)
            {
                arrayA[i, j] = i + j + 10;
            }
        }
        Console.WriteLine("以下输出矩阵 arrayA 结构 !! ");
       myClass1.PrintArray(arrayA, 2, 3);这里又可以？

        for (int i = 0; i < 3; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                arrayB[i, j] = i + j + 1;
            }
        }
        Console.WriteLine("以下输出矩阵 arrayB 结构 !! ");
        myClass1.PrintArray(arrayB, 3, 2);

        Console.WriteLine("将矩阵 arrayA 与 arrayB  相乘输出其结果 !! ");
        myClass1.DMartix(arrayA, arrayB);

        Console.ReadLine();
    }
    void PrintArray(int[,] intArray, int row, int column)
    {
        for (int i = 0; i < row; i++)
        {
            Console.Write("\n");
            for (int j = 0; j < column; j++)
            {
                Console.Write(intArray[i, j] + "\t");
            }
            Console.Write("\n");
        }
        Console.Write("\n");
    }
    void DMartix(int[,] arrayA, int[,] arrayB)
    {
        int[,] resultArray = new int[2, 2];
        int result = 0;
        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                result = 0;
                for (int k = 0; k < 3; k++)
                    result = result + arrayA[i, k] * arrayB[k, j];
                resultArray[i, j] = result;
            }
        }
        PrintArray(resultArray, 2, 2);
    }
}

面向对象
你的类program的对象myclass1又怎么能调用你Matrixm类中PrintArray方法呢？？？

多谢你的回复 我没有看到printarrayA方法是自定义的……我还以为是系统自带的 呵呵 明白了