类定义（包括数据成员和成员函数功能描述）#include<iostream> #include<fstream> #include<iomanip> using namespace std; double M[3][3]; double N[10][10]; bool ReadMatrix() { int i, j; ifstream Nfile("d:\N矩阵.txt"); if (!Nfile) return false; ifstream Mfile("d:\M矩阵.txt"); if (!Mfile) { Nfile.close(); return false; } for (i = 0;i < 10;i++) for (j = 0;j < 10;j++) Nfile >> N[i][j]; for (i = 0;i < 3;i++) for (j = 0;j < 3;j++) Mfile >> M[i][j]; Mfile.close(); Nfile.close(); return true; } double algorithms1(int I, int J) { double Mij, Nij; double a, b; int i, j, in, jn; a = 0; b = 0; for (i = 0;i <= 2;i++) for (j = 0;j <= 2;j++) { Mij = M[i][j]; in = I - i - 1; jn = J - j - 1; if (in < 0 || jn < 0 || in>9 || jn>9) Nij = 0; else Nij = N[in][jn]; a = a + Mij * Nij; b = b + Mij; } if (b != 0) return a / b; else return 0; } double algorithms2(int I, int J) { double Mij, Nij; double a, b; int i, j, in, jn; a = 0; b = 0; for (i = 0;i <= 2;i++) for (j = 0;j <= 2;j++) { Mij = M[i][j]; in = I - i - 1; jn = J - j - 1; if (in < 0 || jn < 0 || in>9 || jn>9) Nij = 0; else Nij = N[9 - in][9 - jn]; a = a + Mij * Nij; b = b + Mij; } if (b != 0) return a / b; else return 0; } int main() { int i, j; double v1, v2; char c; if (!ReadMatrix()) { cout << "打开文件出错，程序退出" << endl; return -1; } cout << "读入矩阵数据成功，请输入I:"; cin >> i; cout << endl << "请输入J:"; cin >> j; cout << "输入的I=" << i << "输入的J= " << j << endl; v1 = algorithms1(i, j); cout << "算法1的结果=" << v1 << endl; v2 = algorithms2(i, j); cout << "算法2的结果=" << v2 << endl; return 0; }

这段代码中并没有定义任何类，只是一些全局变量和函数。如果要将其改为类定义，可以将全局变量M和N作为类的数据成员，并将ReadMatrix()、algorithms1()和algorithms2()作为类的成员函数。具体实现如下：

#include<iostream>
#include<fstream>
#include<iomanip>
using namespace std;

class MatrixCalculator {
private:
    double M[3][3];
    double N[10][10];
public:
    bool ReadMatrix() {
        int i, j;
        ifstream Nfile("d:\N矩阵.txt");
        if (!Nfile) return false;
        ifstream Mfile("d:\M矩阵.txt");
        if (!Mfile) {
            Nfile.close();
            return false;
        }
        for (i = 0;i < 10;i++)
            for (j = 0;j < 10;j++)
                Nfile >> N[i][j];
        for (i = 0;i < 3;i++)
            for (j = 0;j < 3;j++)
                Mfile >> M[i][j];
        Mfile.close();
        Nfile.close();
        return true;
    }
    
    double algorithms1(int I, int J) {
        double Mij, Nij;
        double a, b;
        int i, j, in, jn;
        a = 0;
        b = 0;
        for (i = 0;i <= 2;i++)
            for (j = 0;j <= 2;j++) {
                Mij = M[i][j];
                in = I - i - 1;
                jn = J - j - 1;
                if (in < 0 || jn < 0 || in>9 || jn>9)
                    Nij = 0;
                else
                    Nij = N[in][jn];
                a = a + Mij * Nij;
                b = b + Mij;
            }
        if (b != 0)
            return a / b;
        else
            return 0;
    }
    
    double algorithms2(int I, int J) {
        double Mij, Nij;
        double a, b;
        int i, j, in, jn;
        a = 0;
        b = 0;
        for (i = 0;i <= 2;i++)
            for (j = 0;j <= 2;j++) {
                Mij = M[i][j];
                in = I - i - 1;
                jn = J - j - 1;
                if (in < 0 || jn < 0 || in>9 || jn>9)
                    Nij = 0;
                else
                    Nij = N[9 - in][9 - jn];
                a = a + Mij * Nij;
                b = b + Mij;
            }
        if (b != 0)
            return a / b;
        else
            return 0;
    }
};

int main() {
    MatrixCalculator mc;
    int i, j;
    double v1, v2;
    char c;
    if (!mc.ReadMatrix()) {
        cout << "打开文件出错，程序退出" << endl;
        return -1;
    }
    cout << "读入矩阵数据成功，请输入I:";
    cin >> i;
    cout << endl << "请输入J:";
    cin >> j;
    cout << "输入的I=" << i << "输入的J= " << j << endl;
    v1 = mc.algorithms1(i, j);
    cout << "算法1的结果=" << v1 << endl;
    v2 = mc.algorithms2(i, j);
    cout << "算法2的结果=" << v2 << endl;
    return 0;
}

这样，我们就将这段代码改写成一个包含一个类的程序，使其更加面向对象。