实验四

task 5：

vectorInt.hpp

#include<iostream>

using namespace std;

class vectorInt
{
public:
    vectorInt(int n);
    vectorInt(int n, int value);
    vectorInt(const vectorInt &y);
    ~vectorInt();
    friend void output(vectorInt &t);
    int get_size() const;
    int &at(int i);

private:
    int size;
    int *p;
};

vectorInt::vectorInt(int n) : size{n}
{
    p = new int[size];
    cout << "constructor 1 called." << endl;
}

vectorInt::vectorInt(int n, int value) : size{n}
{
    p = new int[size];
    for(int i = 0; i < size; i++)
    {
        p[i] = value;
    }
    cout << "constructor 2 called." << endl;
}

vectorInt::vectorInt(const vectorInt &y) : size{y.size}
{
    p = new int[size];
    for(int i = 0; i < size; i++)
    {
        p[i] = y.p[i];
    }
    cout << "copy constructor called." << endl;
}
vectorInt::~vectorInt()
{
    delete[] p; 
    cout << "destructor called" << endl;
}

void output(vectorInt &t) 
{
    for(int i = 0; i < t.size; i++)
    {
        cout << t.p[i] << ", ";
    }
    cout << "\b\b " << endl;
}

int vectorInt::get_size() const
{
    return size;
}

int &vectorInt::at(int i)
{
    if(i >= 0 && i < size);
        return p[i];
}

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();
}

task6:

Matrix.hpp

#include <iostream>

using std::cout;
using std::endl;

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
};

// 类Matrix的实现
Matrix::Matrix(int n):Matrix{n, n}{}
Matrix::~Matrix()
{
    delete[] p;
}
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];
    }
}

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[i * cols + j] = value;
}

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];
}

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

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

void Matrix::print() const
{
    for(int i = 0; i < lines; i++)
    {
        for(int j = 0; j < cols; j++)
        {
            cout << p[i * cols + j] << ", ";
        }
        cout << "\b\b " << endl;
    }
}

task6.cpp

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

void test() {
    using namespace std;

    double x[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

    Matrix m1(3, 4);    // 创建一个3 ×4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(4, 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();
}