C++中实现矩阵的加法和乘法实例

#include<iostream>using namespace std;class Matrix{  int row;//矩阵的行  int col;//矩阵的列  int **a;//保存二维数组的元素public:  Matrix();//默认构造函数  Matrix(int r, int c);  Matrix(const Matrix &is);//拷贝构造函数  void Madd(const Matrix &is);//矩阵加  Matrix Mmul(const Matrix &is);//矩阵乘  void display();//显示矩阵元素};Matrix::Matrix(int r, int c){  row = r;  col = c;  a = (int **)malloc(sizeof(int*)*row);  for (int r = 0; r < row; r++)  {    *(a + r) = (int*)malloc(sizeof(int)*col);  }  printf("请输入数：/n");  for (int i = 0; i < row; i++)    for (int j = 0; j < col; j++)      cin >> a[i][j];}Matrix::Matrix(const Matrix & is){//拷贝构造函数  row = is.row;  col = is.col;  a = new int*[row];  for (int i = 0; i < row; i++)  {    a[i] = new int[col];  }  a = is.a;}void Matrix::Madd(const Matrix & is){  if (row != is.row || col != is.col)//判断两矩阵是否符合相加条件  {    cout << "相加的矩阵必须行和列一致";  }  else  {    for (int i = 0; i < row; i++)    {      for (int j = 0; j < col; j++)      {        a[i][j] += is.a[i][j];      }    }  }}Matrix Matrix::Mmul(const Matrix & is){  Matrix M3(this->row, is.col);  if (this->col != is.row)//判断是否符合相乘条件  {    cout << "不符合两矩阵相乘的条件";  }  else  {    for (int i = 0; i < M3.row; i++)    {      for (int j = 0; j < M3.col; j++)      {        M3.a[i][j] = 0;        for (int n = 0; n < is.row; n++)        {          M3.a[i][j] += this->a[i][n] * is.a[n][j];        }      }    }  }  return M3;}void Matrix::display(){//输出矩阵  for (int i = 0; i < row; i++)  {    for (int j = 0; j < col; j++)    {      cout << a[i][j] << " ";    }    cout << endl;  }  cout << endl;}int main(){  Matrix m1(3, 3);  m1.display();  Matrix m2(3, 3);  m2.display();  Matrix m3(3, 2);  m3.display();  cout << "m1+m2=" << endl;  m1.Madd(m2);  m1.display();  Matrix m4(m1.Mmul(m3));  cout << "m1*m3=" << endl;  m4.display();  system("pause");  return 0;}