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

 #include<iostream>
 using namespace std;

 class Matrix
 {
     private:
         int row,list;
         double **HL;
     public:
         Matrix(int r_ = , int l_ = );
         Matrix(int r_ , int l_ , double **newone);
         Matrix(const Matrix & rhs);
         ~Matrix();
         Matrix operator + (const Matrix & rhs);
         Matrix operator - (const Matrix & rhs);
         Matrix operator = (const Matrix & rhs);
         friend ostream & operator << (ostream & os , const Matrix & rhs);
 };

 int i,j;

 Matrix::Matrix(int r_ , int l_):row(r_),list(l_)　　//构造函数
 {
     HL = new double *[row];
     for(i = ;i < row;i++)
         HL[i] = new double [list];
     cout<<"please enter Matrix :"<<endl;
     for(i = ;i < row;i++)
         for(j = ;j < list;j++)
             cin>>HL[i][j];
 } 

 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
 {
     HL = new double *[row];
     for(i = ;i < row;i++)
         HL[i] = new double [list];
     for(i = ;i < row;i++)
         for(j = ;j < list;j++)
             HL[i][j] = newone[i][j];
 } 

 Matrix::Matrix(const Matrix & rhs)
 {
     if(this != & rhs)
     {
         this->row = rhs.row;
         this->list = rhs.list;
         HL = new double *[row];
         for(i = ;i < row;i++)
             HL[i] = new double [list];
         for(i = ;i < row;i++)
             for(j = ;j < list;j++)
                 this->HL[i][j] = rhs.HL[i][j];
     }
 }

 Matrix::~Matrix()　　　　//　析构函数，删除开辟的空间
 {
     cout<<"~ Matrix : row ="<<row<<" , list = "<<list<<endl<<endl;
     for(i = ;i < row;i++)
         delete [] HL[i];
     delete [] HL;
 }

 Matrix Matrix::operator + (const Matrix & rhs)
 {
     if( (this->row == rhs.row)&&(this->list == rhs.list) )
     {
         double **newone;
         int r_,l_;
         r_ = row;l_ = list;
         newone = new double *[row];
         for(i = ;i < row;i++)
             newone[i] = new double [list];
         for(i = ;i < row;i++)
             for(j = ;j < list;j++)
                 newone[i][j] = HL[i][j] + rhs.HL[i][j];
         return Matrix(r_,l_,newone);
     }
 //    else
 //        cout<<"error ——矩阵类型不符 "<<endl;
 }

 Matrix Matrix::operator - (const Matrix & rhs)
 {
     if( (this->row == rhs.row)&&(this->list == rhs.list) )
     {
         double **newone;
         int r_,l_;
         r_ = row;l_ = list;
         newone = new double *[row];
         for(i = ;i < row;i++)
             newone[i] = new double [list];
         for(i = ;i < row;i++)
             for(j = ;j < list;j++)
                 newone[i][j] = HL[i][j] - rhs.HL[i][j];
         return Matrix(r_,l_,newone);
     }
 //    else
 //        cout<<"error ——矩阵类型不符 "<<endl;
 }

 Matrix Matrix::operator = (const Matrix & rhs)
 {
     if((this->row == rhs.row)&&(this->list == rhs.list))
     {
         for(i = ;i < row;i++)
             for(j = ;j < list;j++)
                 this->HL[i][j] = rhs.HL[i][j];
         return (*this);
     }
 //    else
 //        cout<<"error ——矩阵类型不符 "<<endl;
 }

 ostream & operator << (ostream & os,const Matrix & rhs)
 {
     os<<"Matrix : row ="<<rhs.row<<" , list = "<<rhs.list<<endl;
     for(i = ;i < rhs.row;i++)
     {
         for(j = ;j < rhs.list;j++)
             os<<rhs.HL[i][j]<<" ";
         os<<endl;
     }
     return os;
 }

 int main()
 {
     int m,n,x,y;
     cin>>n>>m>>x>>y;
     Matrix aa(n,m),bb(n,m),cc(n,m),dd(x,y);
     cout<<endl<<aa<<endl<<bb<<endl<<cc<<endl<<dd<<endl;
     cout<<(aa+bb+cc)<<endl<<(cc-bb)<<endl;
     return ;
 } 

2019-11-02    15:34:51