C++中Matrix，矩阵的基本运算

利用二维指针开辟空间形成二维数组；

原题为设计一个Matrix类，实现基本的矩阵运算；

初次设计为HL[10][10]数组，存放矩阵元素，后改为二维指针；

主要问题存在于二维指针理解的不透彻，无法理解其开辟空间的方法；

HL = new double *[row];
for(i = 0;i < row;i++)
    HL[i] = new double [list];
其次对于不同类型矩阵相加没有找到合适的处理方式，只能手动控制不使不同类型矩阵相加或相减；
其中 row 为行，list为列，HL为存放矩阵的二维指针；
附上一个new运算符的用法；
https://www.cnblogs.com/2015-16/p/11782595.html

  1 #include<iostream>
  2 using namespace std;
  3 
  4 class Matrix
  5 {
  6     private:
  7         int row,list;
  8         double **HL;
  9     public:
 10         Matrix(int r_ = 0, int l_ = 0);
 11         Matrix(int r_ , int l_ , double **newone);
 12         Matrix(const Matrix & rhs);
 13         ~Matrix();
 14         Matrix operator + (const Matrix & rhs);
 15         Matrix operator - (const Matrix & rhs);
 16         Matrix operator = (const Matrix & rhs);
 17         friend ostream & operator << (ostream & os , const Matrix & rhs);
 18 };
 19 
 20 int i,j;
 21 
 22 Matrix::Matrix(int r_ , int l_):row(r_),list(l_)　　//构造函数
 23 {
 24     HL = new double *[row];
 25     for(i = 0;i < row;i++)
 26         HL[i] = new double [list]; 
 27     cout<<"please enter Matrix :"<<endl;
 28     for(i = 0;i < row;i++)
 29         for(j = 0;j < list;j++)
 30             cin>>HL[i][j];
 31 } 
 32 
 33 Matrix::Matrix(int r_ , int l_ , double **newone ):row(r_),list(l_)　　//构造函数重载，主要用于加法减法中的return使用
 34 {
 35     HL = new double *[row];
 36     for(i = 0;i < row;i++)
 37         HL[i] = new double [list]; 
 38     for(i = 0;i < row;i++)
 39         for(j = 0;j < list;j++)
 40             HL[i][j] = newone[i][j];
 41 } 
 42 
 43 Matrix::Matrix(const Matrix & rhs)
 44 {
 45     if(this != & rhs)
 46     {
 47         this->row = rhs.row;
 48         this->list = rhs.list;
 49         HL = new double *[row];
 50         for(i = 0;i < row;i++)
 51             HL[i] = new double [list]; 
 52         for(i = 0;i < row;i++)
 53             for(j = 0;j < list;j++)
 54                 this->HL[i][j] = rhs.HL[i][j];
 55     }
 56 }
 57 
 58 Matrix::~Matrix()　　　　//　析构函数，删除开辟的空间
 59 {
 60     cout<<"~ Matrix : row ="<<row<<" , list = "<<list<<endl<<endl;
 61     for(i = 0;i < row;i++)
 62         delete [] HL[i];
 63     delete [] HL;
 64 }
 65 
 66 Matrix Matrix::operator + (const Matrix & rhs)
 67 {
 68     if( (this->row == rhs.row)&&(this->list == rhs.list) )
 69     {
 70         double **newone;
 71         int r_,l_;
 72         r_ = row;l_ = list;
 73         newone = new double *[row];
 74         for(i = 0;i < row;i++)
 75             newone[i] = new double [list]; 
 76         for(i = 0;i < row;i++)
 77             for(j = 0;j < list;j++)
 78                 newone[i][j] = HL[i][j] + rhs.HL[i][j];
 79         return Matrix(r_,l_,newone);
 80     }
 81 //    else
 82 //        cout<<"error ——矩阵类型不符 "<<endl; 
 83 }
 84 
 85 Matrix Matrix::operator - (const Matrix & rhs)
 86 {
 87     if( (this->row == rhs.row)&&(this->list == rhs.list) )
 88     {
 89         double **newone;
 90         int r_,l_;
 91         r_ = row;l_ = list;
 92         newone = new double *[row];
 93         for(i = 0;i < row;i++)
 94             newone[i] = new double [list]; 
 95         for(i = 0;i < row;i++)
 96             for(j = 0;j < list;j++)
 97                 newone[i][j] = HL[i][j] - rhs.HL[i][j];
 98         return Matrix(r_,l_,newone);
 99     }
100 //    else
101 //        cout<<"error ——矩阵类型不符 "<<endl; 
102 }
103 
104 Matrix Matrix::operator = (const Matrix & rhs)
105 {
106     if((this->row == rhs.row)&&(this->list == rhs.list))
107     {
108         for(i = 0;i < row;i++)
109             for(j = 0;j < list;j++)
110                 this->HL[i][j] = rhs.HL[i][j];
111         return (*this); 
112     } 
113 //    else
114 //        cout<<"error ——矩阵类型不符 "<<endl; 
115 }
116 
117 ostream & operator << (ostream & os,const Matrix & rhs)
118 {
119     os<<"Matrix : row ="<<rhs.row<<" , list = "<<rhs.list<<endl;
120     for(i = 0;i < rhs.row;i++)
121     {
122         for(j = 0;j < rhs.list;j++)
123             os<<rhs.HL[i][j]<<" ";
124         os<<endl;    
125     }
126     return os;
127 }
128 
129 int main()
130 {
131     int m,n,x,y;
132     cin>>n>>m>>x>>y;
133     Matrix aa(n,m),bb(n,m),cc(n,m),dd(x,y);
134     cout<<endl<<aa<<endl<<bb<<endl<<cc<<endl<<dd<<endl;
135     cout<<(aa+bb+cc)<<endl<<(cc-bb)<<endl;
136     return 0;
137 } 

2019-11-02 15:34:51