实验3 类和对象Ⅱ

一、实验结论

1.实验任务4

#ifndef VECTOR_INT_HPP
#define VECTOR_INT_HPP

#include <iostream>
using namespace std;

class Vector_int{
    public:
        Vector_int(int nn,int v=0);
        Vector_int(Vector_int &vec);
        int &at(int x);
        void print();
        ~Vector_int();
    private:
        int n,value;
        int *p;
};

Vector_int::Vector_int(int nn,int v){
    n=nn;
    value=v;
    p = new int[n];
    for(int i=0;i<n;i++){
        p[i] = value;
    }
    cout << "Create success!" << endl;
}

Vector_int::Vector_int(Vector_int &vec){
    n=vec.n;
    value=vec.n;
    p = new int[n];
    for(int i=0;i<n;i++){
        p[i] = value;
    }
    cout << "Create success!" << endl;
}

int &Vector_int::at(int x){
    return p[x];
}

void Vector_int::print(){
    for(int i=0;i<n;i++){
        cout << p[i];
        if(i!=n-1){
            cout << ",";
        }else{
            cout << endl;
        }
    }
    return;
}

Vector_int::~Vector_int(){
    delete[] p;
    cout << "Delete success!" << endl;
}


#endif

 

#include "Vector_int.hpp"
#include <iostream>

int main(){
    using namespace std; 
    
    Vector_int x1(5);
    x1.print();
    
    Vector_int x2(5,8);
    x2.print(); 
    
    Vector_int y(x2);
    y.print();
    
    y.at(0) = 999;
    y.print();
    
    return 0;
}

 

 2.实验任务5

 

#ifndef MATRIX_HPP
#define MATRIX_HPP

#include <iostream>

using namespace std;

class Matrix
{
public:
    Matrix(int n);                     // 构造函数，构造一个n*n的矩阵
    Matrix(int n, int m);              // 构造函数，构造一个n*m的矩阵
    Matrix(const Matrix &X);           // 复制构造函数，使用已有的矩阵X构造
    ~Matrix();                         //析构函数
    void set(const double *pvalue);     // 用pvalue指向的连续内存块数据为矩阵赋值
    void set(int i, int j, int value); //设置矩阵第i行第j列元素值为value
    double &at(int i, int j);          //返回矩阵第i行第j列元素的引用
    double at(int i, int j) const;     // 返回矩阵第i行第j列元素的值
    int get_lines() const;             //返回矩阵行数
    int get_cols() const;              //返回矩列数
    void print() const;                // 按行打印输出矩阵
private:
    int lines; // 矩阵行数
    int cols;  // 矩阵列数
    double *p; // 指向存放矩阵数据的内存块的首地址
};

Matrix::Matrix(int n){
	lines = n;
	cols = n;
	p = new double[lines*cols];
}
Matrix::Matrix(int n,int m){
	lines = n;
	cols = m;
	p = new double[lines*cols];
}
Matrix::Matrix(const Matrix &X){
	lines = X.lines;
	cols = X.cols;
	p = new double[lines*cols];
	for (int i = 0; i < lines * cols; i++) {
        p[i] = X.p[i];
    }
}
Matrix::~Matrix(){
	delete[] p;
}

void Matrix::set(const double *pvalue){
	for (int i = 0; i < lines * cols; i++) {
        p[i] = pvalue[i];
    }
}

void Matrix::set(int i, int j, int value) {
    p[cols * i + j] = value;
}

double &Matrix::at(int i, int j) {
    return p[cols * i + j];
}

double Matrix::at(int i, int j) const {
    return p[cols * i + j];
}

int Matrix::get_lines() const {
    return lines;
}

int Matrix::get_cols() const {
    return cols;
}

void Matrix::print() const {
    int flag = 0;
    for (int i = 0; i < lines * cols; i++) {
        if (flag != 0 && flag % cols == 0)cout << endl;
        cout << p[i] << ' ';
        flag++;
    }
    cout << endl;
}

#endif

　　

#include <iostream>
#include "matrix.hpp"

int main()
{
    using namespace std;

    double x[] = {1, 2, 3, 4, 5, 6};

    Matrix m1(3, 2);    // 创建一个3×2的矩阵
    m1.set(x);          // 用一维数组x的值按行为矩阵m1赋值
    m1.print();         // 打印矩阵m1的值
    cout << "the first line is: " << endl;
    cout << m1.at(0, 0) << " " << m1.at(0, 1) << endl;
    cout << endl;

    Matrix m2(2, 3);
    m2.set(x);
    m2.print();
    cout << "the first line is: " << endl;
    cout << m2.at(0, 0) << " " << m2.at(0, 1) << " " << m2.at(0, 2) << endl;
    cout << endl;

    Matrix m3(m2);
    m3.set(0, 0, 999);
    m3.print();
}

 

 

二、实验总结

1.释放内存非常重要；

2.查找资料后发现除了上面的方法外，二维数组的建立可以用两层指针来实现，似乎更加符合二维数组的几何结构。