实验四

实验任务五

        vectorInt.hpp

#pragma once
#include<bits/stdc++.h>
using namespace std;
class vectorInt{
    public:
    vectorInt(int n);
    vectorInt(int n,int v);
    vectorInt(const vectorInt &x);
    ~vectorInt();
    int &at(int index);    
    int get_size() const;
    friend void output(vectorInt &xx);
    private:
        int size;
        int *a;
};
int vectorInt::get_size()const{
    return size;
}
vectorInt::vectorInt(int n,int v):size{n}{
    cout<<"constructor 2 called."<<endl;
    a = new int[n];
    for(int i=0;i<n;i++)
    a[i] = v;
}
vectorInt::vectorInt(int n):size{n}{
     cout<<"constructor 1 called."<<endl;
     a = new int[n];
};
vectorInt::~vectorInt(){ 
      delete[] a;
      cout<<"destructor called."<<endl;
}
vectorInt::vectorInt(const vectorInt& x){
    size = x.size;
    a = new int[size];
    for(int i = 0; i < size; ++i)
    a[i] = x.a[i];
   cout << "copy constructor called." << endl;
}
int &vectorInt::at(int index){
    assert(index >= 0 && index < size);
    return a[index];
}
void output(vectorInt &xx){
    for(int i=0;i<xx.get_size();i++)
    cout<<xx.at(i)<<" ";
    cout<<endl;
}

    task5.cpp

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

void test() {
    using namespace std;

    int n;
    cin >> n;
    
    vectorInt x1(n);
    for(auto i = 0; i < n; ++i)
        x1.at(i) = i*i;

    output(x1);

    vectorInt x2(n, 42);
    vectorInt x3(x2);

    output(x2);
    output(x3);

    x2.at(0) = 77;

    output(x2);
    output(x3);
}

int main() {
    test();
}

实验任务六

   Matrix.hpp

#pragma once

#include <bits/stdc++.h>
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按行为矩阵赋值
    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[n*n];
}
Matrix::Matrix(int n,int m):lines{n},cols{m}{
    p = new double[n*m];
}
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(){
    for(int i=0;i<lines*cols;i++)
    delete []p;
}
double &Matrix::at(int i, int j){
    return p[i*cols+j];
}
double Matrix::at(int i, int j) const{
    return p[i*cols+j];
}
void Matrix::set(const double *pvalue){
    int i;
    for(i=0;i<lines*cols;i++)
    p[i] = *(pvalue++);
}
void Matrix::set(int i,int j,int value){
    p[i*cols+j] = value;
}
int Matrix::get_lines() const{ return lines;}             //返回矩阵行数
int Matrix::get_cols() const{ return cols;}
void Matrix::print()const{
     int i;
     for(i=0;i<lines*cols;i++){
         cout<<p[i]; 
        if((i+1)%cols==0) cout<<endl;
         else cout<<",";
    }
}
// 类Matrix的实现：待补足
// ×××

    task6.cpp

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

void test() {
    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;  // 输出矩阵m1第1行两个元素的值
    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);      // 用矩阵m2构造新的矩阵m3
    m3.set(0, 0, 999);  // 将矩阵m3第0行第0列元素值设为999
    m3.print();
}

int main() {
    test();
}

     对于指针和引用的理解还有待提高