2.10 (C++)

Design a class Matrix that has the following private member variables:
int rows
int columns
double * values
Besides, it has the following public object functions:
A constructor Matrix(int rows, int column, double values[]), which initializes all elements in the matrix to the given values. Note that the given values are in one-dimensional, you need to fill then into the two-dimensional matrix correctly.
A copy constructor Matrix(const Matrix & matrix2).
A destructor.
A print function which prints each row of elements in a single line, with each element preceded with 4 spaces.
An operator Matrix Matrix::operator * (const Matrix & matrix2) const.
An operator Matrix Matrix::operator * (double value) const.
EXAMPLE INPUT
4 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
5 4
20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
8
EXAMPLE OUTPUT

1    2    3    4    5
6    7    8    9    10
11    12    13    14    15
16    17    18    19    20

20    19    18    17
16    15    14    13
12    11    10    9
8    7    6    5
4    3    2    1

140    125    110    95
440    400    360    320
740    675    610    545
1040    950    860    770

8    16    24    32    40
48    56    64    72    80
88    96    104    112    120
128    136    144    152    160

主程序 (不能修改)

#include "source.cpp"

Matrix read() {
    int rows;
    int columns;
    double values[1000];
    cin >> rows >> columns;
    for (int i = 0; i < rows * columns; ++ i) {
        cin >> values[i];
    }
    Matrix matrix(rows, columns, values);
    return matrix;
}

int main() {
    Matrix matrix1 = read(); // calls copy constructor
    Matrix matrix2 = read();
    
    double value;
    cin >> value;
    
    matrix1.print();
    cout << endl;
    matrix2.print();
    cout << endl;
    
    Matrix matrix3 = matrix1 * matrix2;
    matrix3.print();
    cout << endl;
    
    Matrix matrix4 = matrix1 * value;
    matrix4.print();
    cout << endl;
}

我的答案

#include <iostream>
using namespace std;

class Matrix{
private:    
    int rows;
    int columns;
    double *addr;
    
    void _init(int rows,int columns,double values[]){
        this->rows=rows;
        this->columns=columns;
        this->addr=new double[rows*columns];
        for (int i = 0; i < rows*columns ; ++ i) {
            this->addr[i]=(values==NULL ? 0: values[i]);
        }
    }
    
public:
    //构造函数1
    Matrix(int rows,int columns){
        this->_init(rows,columns,NULL);
    }
    //构造函数2
    Matrix(int rows,int columns,double values[]){
        this->_init(rows,columns,values);
    }
    //释构函数
    Matrix(const Matrix & m){
        this->_init(m.rows,m.columns,m.addr);
    }
    //=
    Matrix & operator = (const Matrix & m){
        delete [] this->addr;
        this->_init(m.rows,m.columns,m.addr);
        return *this;
    }
    //析构函数
    ~Matrix(){
        delete [] this->addr;
    }
    
    double get(int row, int col) const{
        int index = (row-1)* this->columns + (col-1);
        return this->addr[index];
    }
    
    void set(int row, int col,double val){
        int index = (row-1)* this->columns + col-1;
        this->addr[index] = val;
    }
    
    void print() const {
        for (int i = 0; i < this->rows; ++ i) {
            for (int j = 0; j < this->columns; ++ j) {
                cout << "    " << this->get(i+1,j+1);
            }
            cout<<endl;
        }
    }
    
    Matrix operator * (const Matrix & matrix2) const{
        Matrix m(this->rows,this->rows, NULL);
        for (int i = 0; i < this->rows ; ++ i) {
            for (int j = 0; j < this->rows ; ++ j) {
                int temp=0;
                for (int k = 0; k < this-> columns ; ++ k){
                    temp=temp + this->get(i+1,k+1)*matrix2.get(k+1,j+1);
                } 
                m.set(i+1,j+1,temp);
            }
        }
        return m;
    }
    
    Matrix operator * (double val) const{
        Matrix m(this->rows,this->columns, NULL);
        for (int i = 0; i < this->rows ; ++ i) {
            for (int j = 0; j < this->columns ; ++ j) {
                m.set(i+1,j+1,this->get(i+1,j+1)*val);
            }
        }
        return m;
    }
    
};