task2:
#include <iostream> using std::cout; using std::endl; // 定义Point类 class Point { public: Point(int x0 = 0, int y0 = 0); Point(const Point&p ); ~Point() = default; int get_x() const { return x; } // 内联成员函数 int get_y() const { return y; } // 内联成员函数 void show() const; private: int x, y; }; // Point类的实现 // 构造函数(带有默认形参值) Point::Point(int x0, int y0): x{x0}, y{y0} { cout << "constructor called." << endl; } // 复制构造函数 // 参数必须是自身对象的引用类型 Point::Point(const Point& p): x{p.x}, y{p.y} { cout << "copy constructor called." << endl; } void Point::show() const { cout << "(" << x << ", " << y << ")" << endl; } int main() { Point p1(2, 7); // 构造函数被调用 p1.show(); Point p2 = p1; // 复制构造函数被调用 p2.show(); Point p3{p2}; // 复制构造函数被调用 p3.show(); cout << p3.get_x() << endl; }
task 3:
#include <iostream> #include <iomanip> using std::cout; using std::endl; // 定义时钟类Clock class Clock { public: Clock(int h = 0, int m = 0, int s = 0); Clock(const Clock& t); ~Clock() = default; void set_time(int h, int m = 0, int s = 0); void show_time() const; private: int hour, minute, second; }; // 类Clock实现 Clock::Clock(int h, int m, int s): hour{h}, minute{m}, second{s} { cout << "constructor called" << endl; } Clock::Clock(const Clock& t): hour{t.hour}, minute{t.minute}, second{t.second} { cout << "copy constructor called" << endl; } void Clock::set_time(int h, int m, int s) { hour = h; minute = m; second = s; } void Clock::show_time() const { using std::setw; using std::setfill; cout << setfill('0') << setw(2) << hour << ":" << setw(2) << minute << ":" << setw(2) << second << endl; } // 普通函数定义 Clock reset() { return Clock(0, 0, 0); // 构造函数被调用 } int main() { Clock c1(15, 10, 36); // 构造函数被调用 c1.show_time(); c1 = reset(); // 理论上:复制构造函数被调用 c1.show_time(); Clock c2(c1); // 复制构造函数被调用 c2.set_time(9); c2.show_time(); }
task 4:
#include <iostream> // 定义一个简单抽象类 class X{ public: X(); // 默认构造函数 ~X(); // 析构函数 X(int m); // 构造函数 X(const X& obj); // 复制构造函数 X(X&& obj) noexcept; // 移动构造函数 void show() const; // 显示数据 private: int data; }; X::X(): data{42} { std::cout << "default constructor called.\n"; } X::~X() { std::cout << "destructor called.\n"; } X::X(int m): data{m} { std::cout << "constructor called.\n"; } X::X(const X& obj): data{obj.data} { std::cout << "copy constructor called.\n"; } X::X(X&& obj) noexcept: data{obj.data} { std::cout << "move constructor called.\n"; } void X::show() const { std::cout << data << std::endl; } int main() { X x1; //默认构造函数被编译器自动调用 x1.show(); X x2{2049}; x2.show(); // 构造函数被编译器自动调用 X x3{x1}; // 复制构造函数被编译器自动调用 x3.show(); X x4{ std::move(x2) }; // 移动构造函数被编译器调用 x4.show(); }
X x1;调用默认构造函数X()
X x2{2049}; 调用构造函数X(int m)
X x3{x1}; 调用复制构造函数X(const X& obj)
X x4{ move(x2) }; 调用移动构造函数X(X&& OBJ) noexcept
程序执行到最后一行调用四次析构函数~X(),调用的顺序为x4,x3,x2,x1
task 5:
#include <iostream> #include <iomanip> // 矩形类Rectangle的定义和实现 class Rectangle{ public: Rectangle(); ~Rectangle(); Rectangle(double l, double w); Rectangle(const Rectangle& rect); void resize(double times); void resize(double l_times, double w_times); double len() const{ return length; } double wide() const{ return width; } double area() const{ return width*length; } double circumference() const{ return 2*(length+width); } private: double length; double width; }; Rectangle :: Rectangle() : length{2.0}, width{1.0}{} Rectangle::~Rectangle(){} Rectangle :: Rectangle(double l, double w) : length{l}, width{w}{} Rectangle::Rectangle(const Rectangle& rect) : length{ rect.length }, width{ rect.width }{} void Rectangle::resize(double times) { length = length * times; width = width * times; } void Rectangle::resize(double l_times, double w_times) { length = length * l_times; width = width * w_times; } // 普通函数, 用于输出矩形信息 void output(const Rectangle &rect) { using namespace std; cout << "矩形信息: \n"; cout << fixed << setprecision(2); // 控制输出格式:以浮点数形式输出、小数部分保留两位 // 补足代码:分行输出矩形长、宽、面积、周长 cout << "长: " << rect.len() << endl; cout << "宽: " << rect.wide() << endl; cout << "面积:" << rect.area() << endl; cout << "周长:" << rect.circumference() << endl; cout << endl; } // 主函数,测试Rectangle类 int main() { Rectangle rect1; // 默认构造函数被调用 output(rect1); Rectangle rect2(10, 5); // 带有两个参数的构造函数被调用 output(rect2); Rectangle rect3(rect1); // 复制构造函数被调用 rect3.resize(2); // 矩形rect3的长和宽同时缩放2倍 output(rect3); rect3.resize(5, 2); // 矩形rect3的长缩放5倍, 宽缩放2倍 output(rect3); }
标签:const,int,double,width,length,实验,Rectangle From: https://www.cnblogs.com/miantiaooooo/p/16754358.html