实验4 类与数组、指针

实验任务5：

#include <iostream>
#include "vectorInt.h"
using namespace std;
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();
}

#pragma once
#include<iostream>
#include<cassert>
using namespace std;
class vectorInt
{
public:
    vectorInt(int n);
    vectorInt(int n,int value);
    vectorInt(const vectorInt& vp);
    int &at(int i);
    int get_size();
    friend void output(vectorInt &v);
    ~vectorInt();
private:
    int size;
    int* p;
};
vectorInt::vectorInt(int n) :size{ n }
{
    cout << "constructor 1 called." << endl;
    p = new int[n];
}
vectorInt::vectorInt(int n, int value) :size{ n }
{
    cout << "constructor 2 called." << endl;
    p = new int[n];
    for (auto i = 0; i < size; ++i)
        p[i] = value;
}
vectorInt::vectorInt(const vectorInt& vp):size{vp.size}
{
    cout << "copy constructor called." << endl;
    p = new int[size];
    for (auto i = 0; i < size; ++i)
        p[i] = vp.p[i];
}
int& vectorInt::at(int i)
{
    return p[i];
}
int vectorInt::get_size()
{
    return size;
}
void output(vectorInt& v)
{
    for (auto i = 0; i < v.size; ++i)
        cout << v.p[i] << " ";
    cout << endl;
}
vectorInt::~vectorInt()
{
    cout << "destructor called." << endl;
    delete[] p;
}

实验任务6：

#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();
    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();
}

#pragma once
#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):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[X.lines * X.cols];
    for (auto i = 0; i < lines * cols; ++i)
        p[i] = X.p[i];
}
Matrix::~Matrix()
{
    delete[]p;
}
void Matrix::set(const double* pvalue)
{
    for (auto 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 (auto i = 0; i < lines; i++)
    {
        for (auto j = 0; j < cols; j++)
            cout << p[i * cols + j]<<" ";
        cout << endl;
    }    
}