实验任务1
task1_1.cpp
#include<iostream> #include<string> #include<vector> int main() { using namespace std; string s1; string s2{"c plus plus"}; string s3{s2}; string s4=s2; s1="oop"; vector<string> v1; v1.push_back(s1); v1.push_back(s2+"1"); v1.push_back(s3+"2"); v1.push_back(s4+"3"); cout<<"output1"<<endl; for(auto item:v1) cout<<item<<endl; cout<<"output2:"; for(auto p=v1.begin();p!=v1.end();++p) cout<<*p<<endl; cout<<"output3:"<<endl; for(auto i=0;i<v1.size();++i) cout<<v1[i]<<endl; vector<string> v2{v1.rbegin(),v1.rend()}; cout<<"v2:"<<endl; for(auto item:v2) cout<<item<<endl; }
测试结果:
task1_2.cpp
#include <iostream> #include <string> #include <vector> #include <cmath> #include <cstdlib> #include <time.h> // 定义模板函数,用于输出vector容器对象元素的值 template<typename T> void output(const T& obj) // 引用作为函数参数 { for(auto item: obj) std::cout << item << " "; std::cout << std::endl; } int main() { using namespace std; vector<int> v1{1, 9, 8, 4}; v1.insert(v1.begin(), 2022); // 在v1.begin()之前的位置插入 v1.insert(v1.end(), 2023); // 在v1.end()之前的位置插入 cout << "v1: "; output(v1); v1.pop_back(); // 从v1尾部删除数据项 v1.erase(v1.begin()); // 删除v1.begin()位置的数据项 cout << "v1: "; output(v1); vector<string> v2{"《1984》", "《动物农场》", "《美丽新世界》"}; cout << "v2: "; output(v2); }
实验结果:
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实验任务2
task2.cpp
#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(4, 5); // 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; }
测试结果:
更换一组Point对象坐标数据测试结果:
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实验任务3
task3.cpp
#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(12, 0, 5); // 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(6); c2.show_time(); }
测试结果:
更换一组Clock对象数据测试结果:
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实验任务4
task4.cpp
#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(); }
测试结果:
具体哪些行代码执行时,构造函数被调用,以及,具体被调用的是哪一个构造函数
什么时候析构函数被调用,调用顺序是怎样的
创建x1、x2、x3、x4的时候构造函数被调用。
x1调用:
X::X(): data{42} { std::cout << "default constructor called.\n"; }
x2调用:
X::~X() { std::cout << "destructor called.\n"; }
x3调用:
X::X(const X& obj): data{obj.data} { std::cout << "copy constructor called.\n"; }
x4调用:
X::X(X&& obj) noexcept: data{obj.data} { std::cout << "move constructor called.\n"; }
程序运行结束后,析构函数被调用,释放x1,x2,x3,x4的内存空间。
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实验任务5
task5.cpp
#include<iostream> #include<iomanip> //矩形类Rectangle的定义和实现 class Rectangle { public: Rectangle(double l = 2.0, double w = 1.0); Rectangle(const Rectangle& obj); ~Rectangle() = default; double len() const { return length; } double wide() const { return width; } double area() const { return length * width; } double circumference() const { return 2 * (length + width); } void resize(int times); void resize(int l_times, int w_times); private: double length, width; }; Rectangle::Rectangle(double l, double w) { length = l; width = w; } Rectangle::Rectangle(const Rectangle& obj) { length = obj.length; width = obj.width; } // 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); cout << left << setw(8) << "长:" << rect.len() << endl << setw(8) << "宽:" << rect.wide() << endl << setw(8) << "面积:" << rect.area() << endl << setw(8) << "周长:" << rect.circumference() << endl; cout << endl; } void Rectangle::resize(int times) { length *= times; width *= times; } void Rectangle::resize(int i_times, int w_times) { length *= i_times; width *= w_times; } // 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); }
测试结果:
标签:const,cout,v1,对象,int,实验,obj,include From: https://www.cnblogs.com/lee404error/p/16738954.html