C++中Matrix(矩陣)的基本運算( +、-、=、<<)

利用二維指針開辟空間形成二維數組；

原題為設計一個Matrix類，實現基本的矩陣運算；

初次設計為HL[10][10]數組，存放矩陣元素，后改為二維指針；

主要問題存在於二維指針理解的不透徹，無法理解其開辟空間的方法；

HL = new double *[row];
for(i = 0;i < row;i++) HL[i] = new double [list];

其次對於不同類型矩陣相加沒有找到合適的處理方式，只能手動控制不使不同類型矩陣相加或相減；
其中 row 為行，list為列，HL為存放矩陣的二維指針；

附上一個new運算符的用法；

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_ = 0, int l_ = 0);
        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_)　　//構造函數
{
    HL = new double *[row];
    for(i = 0;i < row;i++)
        HL[i] = new double [list]; 
    cout<<"please enter Matrix :"<<endl;
    for(i = 0;i < row;i++)
        for(j = 0;j < list;j++)
            cin>>HL[i][j];
} 

Matrix::Matrix(int r_ , int l_ , double **newone ):row(r_),list(l_)　　//構造函數重載，主要用於加法減法中的return使用
{
    HL = new double *[row];
    for(i = 0;i < row;i++)
        HL[i] = new double [list]; 
    for(i = 0;i < row;i++)
        for(j = 0;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 = 0;i < row;i++)
            HL[i] = new double [list]; 
        for(i = 0;i < row;i++)
            for(j = 0;j < list;j++)
                this->HL[i][j] = rhs.HL[i][j];
    }
}

Matrix::~Matrix()　　　　//　析構函數，刪除開辟的空間
{
    cout<<"~ Matrix : row ="<<row<<" , list = "<<list<<endl<<endl;
    for(i = 0;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 = 0;i < row;i++)
            newone[i] = new double [list]; 
        for(i = 0;i < row;i++)
            for(j = 0;j < list;j++)
                newone[i][j] = HL[i][j] + rhs.HL[i][j];
        return Matrix(r_,l_,newone);
    }
//    else
//        cout<<"error ——矩陣類型不符 "<<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 = 0;i < row;i++)
            newone[i] = new double [list]; 
        for(i = 0;i < row;i++)
            for(j = 0;j < list;j++)
                newone[i][j] = HL[i][j] - rhs.HL[i][j];
        return Matrix(r_,l_,newone);
    }
//    else
//        cout<<"error ——矩陣類型不符 "<<endl; 
}

Matrix Matrix::operator = (const Matrix & rhs)
{
    if((this->row == rhs.row)&&(this->list == rhs.list))
    {
        for(i = 0;i < row;i++)
            for(j = 0;j < list;j++)
                this->HL[i][j] = rhs.HL[i][j];
        return (*this); 
    } 
//    else
//        cout<<"error ——矩陣類型不符 "<<endl; 
}

ostream & operator << (ostream & os,const Matrix & rhs)
{
    os<<"Matrix : row ="<<rhs.row<<" , list = "<<rhs.list<<endl;
    for(i = 0;i < rhs.row;i++)
    {
        for(j = 0;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 0;
} 

 2019-11-02    15:34:51