题目：

 假设square_matrix是n阶整型方阵，请实现下列运算：

（1）cin>> square_matrix

（2）cout<< square_matrix

（3）IntMatrix(n)生成一个n阶单位矩阵

（4）square_matrix+IntMatrix(n)

（5）square_matrix_A=square_matrix_B

源代码：

  1 //matrix.h
  2 #include<iostream>
  3 using namespace std;
  4 
  5 class Square_matrix;
  6 
  7 class IntMatrix{
  8     public:
  9         IntMatrix(int inputn)
 10         {
 11             n=inputn;
 12             int i,j;
 13             q=new int *[n];
 14             for(i=0;i<n;i++)
 15                 q[i]=new int[n];
 16             for(i=0;i<n;i++)
 17             {
 18                 for(j=0;j<n;j++)
 19                 {
 20                     if(i==j)
 21                         q[i][j]=1;
 22                     else
 23                         q[i][j]=0;
 24                 }
 25             }
 26             //cout<<"define a "<<n<<" order int matrix."<<endl;
 27         }
 28         friend class Square_matrix;
 29         friend Square_matrix operator+(const Square_matrix &,const IntMatrix &);
 30         ~IntMatrix()
 31         {
 32             int i,j;
 33             for(i=0;i<n;i++)
 34                 delete []q[i];
 35             delete []q;
 36             cout<<"the intmatrix is deleted!"<<endl;
 37         }
 38     private:
 39         int n;
 40         int **q;
 41 };
 42 
 43 class Square_matrix{
 44     public:
 45         Square_matrix(int inputn)
 46         {
 47             n=inputn;
 48             p=new int *[n];
 49             int i,j;
 50             for(i=0;i<n;i++)
 51                 p[i]=new int[n];
 52             //cout<<"you have define a "<<n<<" order matrix."<<endl;
 53         }
 54         friend ostream &operator<<(ostream &,const Square_matrix &);
 55         friend istream &operator>>(istream &,Square_matrix &);
 56         Square_matrix & operator=(const Square_matrix & m)
 57         {
 58             if(this==&m) return *this;
 59             int i,j;
 60             delete p;
 61             for(i=0;i<n;i++)
 62                 p[i]=new int[m.n];
 63             n=m.n;
 64             for(i=0;i<n;i++)
 65                 for(j=0;j<n;j++)
 66                     p[i][j]=m.p[i][j];
 67             return *this;
 68         }
 69         friend Square_matrix operator+(const Square_matrix &,const IntMatrix &);
 70         ~Square_matrix()
 71         {
 72             int i,j;
 73             for(i=0;i<n;i++)
 74                 delete []p[i];
 75             delete []p;
 76             cout<<"the matrix is deleted!"<<endl;
 77         }
 78     private:
 79         int **p;
 80         int n;
 81 };
 82 
 83 istream &operator>> (istream & input,Square_matrix &m)
 84 {
 85     int i,j;
 86     int mn=m.n;
 87     //cout<<"the order of the matrix is:"<<mn<<endl;
 88     for(i=0;i<mn;i++)
 89     {
 90         for(j=0;j<mn;j++)
 91         {
 92             input>>m.p[i][j];
 93         }
 94     }
 95     return input;
 96 }
 97 
 98 ostream &operator<< (ostream & output,const Square_matrix &m)
 99 {
100     int i,j;
101     int mn=m.n;
102     for(i=0;i<mn;i++)
103     {
104         for(j=0;j<mn;j++)
105             output<<m.p[i][j]<<"  ";
106         output<<endl;
107     }
108     return output;
109 }
110 
111 Square_matrix operator+(const Square_matrix &m1,const IntMatrix &m2)
112 {
113     int n=m1.n;
114     Square_matrix mt(n);
115     int i,j;
116     for(i=0;i<n;i++)
117         for(j=0;j<n;j++)
118             mt.p[i][j]=m1.p[i][j]+m2.q[i][j];
119     return mt;
120 };

 1 //main.cpp
 2 #include<iostream>
 3 #include "matrix.h"
 4 
 5 using namespace std;
 6 
 7 int main()
 8 {
 9 //    const int n=2;
10     int n;
11     cout<<"the order of the Square Matrix:";
12     cin>>n;
13     Square_matrix m0(n);
14     cout<<"Input the elements:"<<endl;
15     cin>>m0;
16     cout<<"m0:"<<endl;
17     cout<<m0;
18     Square_matrix m1(n);
19     cout<<"m1=m0"<<endl<<"m1:"<<endl;
20     m1=m0;
21     cout<<m1;
22     Square_matrix m3(n);
23     m3=m0+IntMatrix(n);
24     cout<<"m3=m0+Intmatrix("<<n<<")"<<endl<<"m3:"<<endl;
25     cout<<m3;
26     return 0;
27 }