#include <iostream>

#include <cassert>

using namespace std;

class Vector_int

{

public:

    Vector_int(int n, int value = 0);

    Vector_int(const Vector_int& x); // 复制构造函数

    ~Vector_int();

    int& at(int index); // 返回下标为index的元素引用

private:

    int size; // 动态数组的大小

    int* p;

};

Vector_int::Vector_int(int n, int value): size(n)

{

    cout << "dynamic create vector..." << endl;

    p = new int[size];

    for (int i = 0; i < size; i++)

    {

        p[i] = value;

    }

}

Vector_int::Vector_int(const Vector_int& x) : size(x.size)

{

    p = new int[size];

    for (auto i = 0; i < size; ++i) // 通过for循环实现对p指向的内存空间的数据复制

        p[i] = x.p[i];

}

Vector_int::~Vector_int()

{

    cout << "deleting..." << endl;

    delete[] p;

}

int& Vector_int::at(int index)

{

    assert(index >= 0 && index < size);

    return p[index];

}

#include <iostream>

#include "Vector_int.hpp"

int main()

{

    using namespace std;

    int n;

    cout << "input size: ";

    cin >> n;

    Vector_int t(n);

    cout << t.at(0) << endl;

    Vector_int x(n, 6);

    cout << x.at(0) << endl;

    Vector_int y(x);

    cout << y.at(0) << endl;

    x.at(0) = 999;

    cout << x.at(0) << endl;

    cout << y.at(0) << endl;

}

#ifndef MATRIX_H

#define MATRIX_H

#include <iostream>

#include <cassert>

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

};

// 类Matrix的实现：

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 (auto i = 0; i < lines * cols; i++)

        p[i] = X.p[i];

}

Matrix::~Matrix()

{

    delete[] p;

}

void Matrix::set(const double* pvalue)

{

    int i = 0;

    while (pvalue + i && i < lines * cols)

    {

        p[i] = pvalue[i];

        i++;

    }

}

void Matrix::set(int i, int j, int value)

{

    assert(i < lines&& j < cols);

    p[i * cols + j] = value;

}

double& Matrix::at(int i, int j)

{

    double& m = p[i * cols + j];

    return m;

}

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 (auto i = 0; i < lines * cols; i++)

    {

        cout << p[i] << ", ";

        if ((i + 1) % cols == 0)

            cout << "\b\b " << endl;

    }

}

#endif

#include <iostream>

#include "Matrix.hpp"

int main()

{

    using namespace std;

    double x[] = { 6, 4, 1, 3, 5, 7, 7, 1, 3, 5, 4, 2 };

    Matrix m1(6, 2); // 创建一个6×2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(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();

}