实验3 类和对象Ⅱ

实验任务4

vector_int.hpp

#ifndef _VECTOR_INT_HPP_
#define _VECTOR_INT_HPP_

#include <iostream>
#include <cassert>

using namespace std;

class Vector_int
{
    public:
        Vector_int(int s, int v = 0);
        Vector_int(const Vector_int &x);
        int& at(int p);
        ~Vector_int();
        void print();

    private:
        int *base, size, value;
};
Vector_int::Vector_int(int s, int v/*= 0*/) : size{s}, value{v}
{
    base = new int[size];
    for(int i = 0; i < size; i++)
      base[i] = value;
    
    cout << "Constructor called." << endl;
}
Vector_int::Vector_int(const Vector_int &x)
{
    size = x.size;
    value = x.value;
    base = new int[size];

    for(int i = 0; i < size; i++)
      base[i] = x.base[i];

    cout << "Copy constructor called." << endl;
}
inline int& Vector_int::at(int p)
{
    assert(p >= 0 && p < size);
    return base[p];
}
Vector_int::~Vector_int()
{
    delete[] base;

    cout << "Destructor called." << endl;
}
void Vector_int::print()
{
    for(int i = 0; i < size; i++)
      cout << base[i] << " ";
    cout << endl;
}

#endif

task4.cpp

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

using namespace std;

int main()
{
    Vector_int v1(10);
    Vector_int v2(15, 1);

    v1.at(4) = 9;

    cout << v2.at(6) << endl;

    Vector_int v3(v1);
    
    v3.at(3) = -1;

    cout << "v1:" << endl;
    v1.print();
    cout << "v2:" << endl;
    v2.print();
    cout << "v3:" << endl;
    v3.print();
    return 0;
}

运行结果

实验任务5

Matrix.hpp

#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)
{
    assert(i >= lines || j >= cols || i < 0 || j < 1);
    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];
            if(j < cols - 1)
              cout << ", ";
        }
        cout << endl;
    }
}

// 类Matrix的实现：待补足
// ×××

#endif

task5.cpp

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

int main()
{
    using namespace std;

    double x[] = {11, 21, 13, 54, 35, 62, 11, 22, 33};

    Matrix m1(3, 3);    
    m1.set(x);          
    m1.print();         
    cout << "the first line is: " << endl;
    cout << m1.at(0, 0) << " " << m1.at(0, 1) << m1.at(0, 2) << " " << endl;
    cout << endl;

    double x2[] = {11, 21, 13, 54, 35, 62};

    Matrix m2(2, 3);
    m2.set(x2);
    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, 1, 8848);
    m3.print();
}

运行截图

实验总结

以返回引用的形式既可以输出数值，也可以用等号赋值的形式修改数据