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期末速成C++【大题汇总完】

news 2025/1/7 11:30:59

目录

1.单例模式

2.RTTI

3.删除小于平均数的元素-无效迭代器

4.排序

5.函数/运算符重载声明

6.复数类

7.点和三角形

总结

1.单例模式

#include<iostream>
using namespace std;//单例模式
class Foo {
public://类的构造析构函数（略）//针对name GetName-return SetName-name=strstring GetName() { return name; }void SetName(string str) { name = str; }//注意！列表初始化是构造函数特有的（：），域操作符（：：）//针对静态变量_instance-staticstatic Foo* GetInstance() {if (_instance == nullptr){_instance = new Foo;}return _instance;}private:Foo() {};//私有构造函数static Foo* _instance;string name;
};//_instance初始化为nullptr
Foo* Foo::_instance = nullptr;//类外_instance
//Foo* Foo::GetInstance()
//{
//	if (_instance == nullptr)
//	{
//		_instance = new Foo;
//	}
//	return _instance;
//}//域外实现
//string Foo::GetName()
//{
//	return name;
//}//void Foo::SetName(string str)
//{
//	name = str;
//}void Fun()
{Foo* q = Foo::GetInstance();q->SetName("Alice");
}
int main()
{Foo* p = Foo::GetInstance();//Foo::p->SetName("Bob");Fun();cout << p->GetName() << endl;
}

2.RTTI

#include<iostream>
#include<vector>
#include<list>
#include<fstream>
using namespace std;
//RTTI
//animal动物-Bird鸟-Dog狗-Cat猫
//1.动物都会吃饭
//2.动物都会叫，鸟-叽叽，狗-汪汪
//3.鸟-飞，狗-跑//1.容器指针
//2.文件读写入-ifs
// 3.重载
//4.遍历RTTIclass Animal {
public:Animal(string str):name(str){}virtual ~Animal(){}//1.共同的void Eat() { cout << "吃饭饭" << endl; }//2.共同-方式不同的-纯虚析构函数virtual void shout() = 0;
private:string name;
};//域外-构造析构
//Animal::Animal(string str) :name(str){}
//Animal::~Animal() {}//在类外实现的时候，虚析构函数是不带virtual关键字
//void Animal::Eat()
//{
//	cout << "吃饭饭" << endl;
//}//鸟
class Bird :public Animal {
public:Bird(string str):Animal(str){}~Bird(){}//2.void shout() { cout << "吱吱" << endl; }//3.void Fly() { cout << "飞" << endl; }
};//void Bird::shout() { cout << "吱吱" << endl; }
//void Bird::Fly() { cout << "飞" << endl; }class Dog :public Animal {
public:Dog(string str):Animal(str){}~Dog(){}//2.void shout() { cout << "汪汪" << endl; }//3.void Run() { cout << "跑" << endl; }};//void Dog::shout() { cout << "汪汪" << endl; }
//void Dog::Run() { cout << "跑" << endl; }//重载
ifstream& operator>>(ifstream& ifs, vector<Animal*>& all)
{string type,name;ifs >> type >> name;if (type == "狗"){all.push_back(new Dog(name));}if (type == "鸟"){all.push_back(new Bird(name));}return ifs;
}int main()
{vector<Animal*>allAnimal;//容器里面是类指针一个一个的狗、鸟//文件操作ios:in-以读的方式从date文件输出ifsifstream ifs("data.txt", ios::in);while (!ifs.eof())//ifs流输出{ifs >> allAnimal;}ifs.close();//遍历for (Animal* p : allAnimal){p->Eat();p->shout();//3.if (typeid(*p) == typeid(Dog)){Dog* pd = dynamic_cast<Dog*>(p);pd->Run();}if (typeid(*p) == typeid(Bird)){Bird* pb = dynamic_cast<Bird*>(p);pb->Fly();}}//释放for (Animal* pt : allAnimal){delete pt;}
}

3.删除小于平均数的元素-无效迭代器

//删除小平平均数的元素-无效迭代器
//1.插入10个随机数-打印显示出来
//2.计算平均数-输出平均数
//3.for循环遍历：删除小平平均数的元素-打印出来
//拼写正确#include <iostream> 
#include <list>
#include<vector>
#include <algorithm> 
#include <numeric>   
using namespace std;int main()
{vector<int> all;//1.generate_n(back_inserter(all), 10, []() {return rand() % 100; });copy(all.begin(), all.end(), ostream_iterator<int>(cout, " "));//2.float ave = static_cast<float>(accumulate(all.begin(), all.end(), 0)) / all.size();cout << "ave:" << ave << endl;//3.vector<int>::iterator itr;//指针for (auto itr = all.begin(); itr != all.end(); ){if (*itr < ave){itr = all.erase(itr);}else{itr++;}}
}

4.排序

//排序
//1.默认
//2.greate
//3.二元谓词cop1
//4.lambda表达式
//5.重载cop2类#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
bool cop1(float f1, float f2)
{return ((int)f1 % 10) > ((int)f2 % 10);
}class cop2 {
public:cop2(int cen):center(cen){}bool operator()(float f1, float f2){return (abs(f1 - center)) < (abs(f2 - center));}
private:int center;
};
int main()
{vector<float> vc;sort(vc.begin(), vc.end());//默认升序sort(vc.begin(), vc.end(), greater<float>());//默认降序greater<float>()sort(vc.begin(), vc.end(), cop1);//二元谓词-不传参-降序int cen = 99;sort(vc.begin(), vc.end(), [cen](float f1, float f2) { return (abs(f1 - cen)) > (abs(f2 = cen)); });//lambda表达式sort(vc.begin(), vc.end(), cop2(cen));
}

5.函数/运算符重载声明

//重载声明
//1.无参构造函数
//2.拷贝构造函数
//3.类型转换构造函数
//4.析构函数
//5.默认赋值运算符=
//6.++ --
//7.+=
//8.下标运算符a[1]='X' a[1]=6
//9.+ a+b=c
//10.类型转换函数
//11.输出输入友元
#include<iostream>
using namespace std;class Bar {friend Bar& operator<<(iostream& ios, const Bar&);friend Bar& operator>>(ifstream& ifs, Bar&);
public:Bar();Bar(const Bar& other);Bar(const string& other);~Bar();Bar& operator=(const Bar& other);Bar& operator++();Bar operator--(int);//后置intchar& operator[](int);Bar operator+(const Bar& other);operator string();//static_cast//dynamic_cast
};

6.复数类

//#include<iostream>
#include<iostream>
#include<algorithm>
using namespace std;//复数类
class Complex {friend ostream& operator<<(ostream& o, const Complex& other);friend Complex operator+(const Complex& A, const Complex& B){return Complex(A.r + B.r, A.i + B.i);}
public:Complex(int a = 0, int b = 0) :r(a), i(b) {}int& operator[](char c){if (c == 'r')return r;if (c == 'i')return i;}Complex operator++(int){Complex temp = *this;r++, i++;return temp;}explicit operator float(){return sqrt(r * r + i * i);}
private:int r, i;//int
};int main()
{Complex a, b;//a = ++b;a = b++;		// 后置++，参数列表中多一个无用的int 前置++可以有引用a = 10 + b;		// 1.自定义全局函数重载 2.C++自己定义的int相加（默认类型转换-类型转换运算符）-不能默认转换只能强制转换，显示调用a['r'] = 1, a['i'] = 2;	  // 下标运算符float f = static_cast<float>(a); //❗c++静态和动态类型转换都要考❗//float f = (float)a;
}

7.点和三角形

//点和三角形
//浮点数，列表初始化，运算符的重载#include<ostream>
#include<array>
class Point {friend class Triangle;//声明友元类❗//输出运算符的重载friend ostream& operator<<(ostream& o, const Point& p)//❗{o << "[" << p. x << "," << p.y <<"]";return o;//考❗}public:Point(int xx,int yy):x(xx),y(yy){} //构造函数列表初始化❗~Point();//析构函数//计算两点距离float GetDistance(const Point& other) {return sqrt((x - other.x) * (x - other.x) + (y - other.y) * ((y - other.y)));}//+重载 两点相加没有& ❗Point operator+ (const Point& other) {return Point(x + other.x, y + other.y);}private:int x, y;//float};class Triangle {//输出运算符的重载friend ostream& operator<<(ostream& o, const Triangle& t){o << "[" << t.all[0] << "," << t.all[1] << ","<<t.all[2]<<"}";return o;//考❗}public://三个点-用数组元素 去列表初始化❗Triangle(const Point& p1, const Point& p2, const Point& p3) :all{p1, p2, p3}{}  //构造函数-列表初始化//三个边-根据三个点初始化❗Triangle(float a, float b, float c) :all{ Point{ 0,0 }, Point{ a,0 }, Point{ 0,0 } } {all[2].x = ........;all[2].y = ........;}//计算面积float GetArea() {//变长float a = all[0].GetDistance(all[1]);❗float b = all[1].GetDistance(all[2]);float c = all[2].GetDistance(all[0]);float p = (a + b + c) / 2.0f;return sqrt(....);}//Triangle t;// t[0]=Point{1,2};//下标运算符重载❗Point& operator[](int index) { return all[index]; }private://表示定义了一个名为 all 的数组，该数组存储了3个 Point 类型的元素。array<Point, 3> all; //考<>❗
};

总结

1月5号复习，明天考试今天再敲遍代码。老徐一切顺利！
//单例模式#include<iostream>
using namespace std;
class Foo {
public:void SetName(string str) { name = str; }string GetName() { return name; }static Foo* GetInstance() //❗类外实现不必加static{if (_instance == nullptr){_instance = new Foo;}return _instance;}
private:Foo() {};//❗私有构造函数static Foo* _instance;string name;
};Foo* Foo::_instance = nullptr;void Fun()
{Foo* pd = Foo::GetInstance();pd->SetName("Alice");
}int main()
{Foo* pf = Foo::GetInstance();//❗调用必须加上::pf->SetName("Bob");Fun();cout << pf->GetName() << endl;
}//RTTI
//人：男生和女生
//吃饭
//体育课-打篮球和跳绳
//玩游戏和逛街
#include<iostream>
#include<list>
#include<fstream>
using namespace std;class Person {
public:Person(string str):name(str){}virtual ~Person(){}void Eat() { cout << "吃饭" << endl; }virtual void PE() = 0;
protected:string name;
};class Boy:public Person //❗继承是:符号
{
public:Boy(string str):Person(str){}~Boy(){}void PE() { cout << "打篮球" << endl; }void Game() { cout << "打游戏" << endl; }
};class Girl :public Person
{
public:Girl(string str):Person(str){}~Girl() {};void PE() { cout << "跳绳" << endl; }void Shopping() { cout << "购物" << endl; }
};
ifstream& operator>>(ifstream& ifs, list<Person*>& li)//❗
{string type, name;ifs >> type >> name;if (type == "男生"){li.push_back(new Boy(name));//❗}if (type == "女生"){li.push_back(new Girl(name));}return ifs;
}
int main()
{list<Person*> li;ifstream ifs("data.txt", ios::in);//:: ❗while (!ifs.eof()){ifs >> li;}ifs.close();for (Person* p : li){p->Eat();p->PE();if (typeid(*p) == typeid(Boy))//*p❗{Boy* pb = dynamic_cast<Boy*>(p);pb->Game();}if (typeid(*p) == typeid(Girl)){Girl* pg = dynamic_cast<Girl*>(p);pg->Shopping();}}for (Person* pt : li){delete pt;}
}//无效迭代器-删除小于平均数的元素
#include<iostream>
#include<list>
#include<vector>
#include<algorithm>
#include<numeric>using namespace std;
int main()
{vector<int> vc;generate_n(back_inserter(vc), 10, []() {return rand() % 100; });copy(vc.begin(), vc.end(), ostream_iterator<int>(cout, " "));float ave = static_cast<float>(accumulate(vc.begin(), vc.end(), 0) )/ vc.size();//vector<int>::iterator itrfor (auto itr = vc.begin(); itr != vc.end(); ){if (*itr < ave){itr = vc.erase(itr);}else{itr++;}}}//排序
#include<iostream>
#include<vector>
#include<algorithm>
#include<numeric>
using namespace std;
bool cop1(float f1, float f2)
{return (int)f1 % 10 > (int)f2 % 10;
}class cop2 {
public:cop2(int cen):center(cen){}bool operator()(float f1, float f2)//❗{return (abs(f1 - center)) > (abs(f2 - center));}
private:int center;
};int main()
{vector<float> vc;sort(vc.begin(), vc.end());//升序sort(vc.begin(), vc.end(), greater<float>());//❗sort(vc.begin(), vc.end(), cop1);int cen = 99;sort(vc.begin(), vc.end(), [cen](float f1, float f2) {return (abs(f1 - cen)) > (abs(f1 - cen)); });sort(vc.begin(), vc.end(), cop2(cen));}//复数类+ 后置++无&
//const 拷贝/类型转换/输出
#include<iostream>
using namespace std;
class Complex {friend ifstream& operator>>(ifstream& ifs, Complex& other);friend ostream& operator<<(ostream& o, const Complex& other);friend Complex operator+(const Complex& c1, const Complex& c2)//+= +{return Complex(c1.i + c2.i, c1.r + c2.r);}
public:Complex(){}~Complex(){}Complex(const Complex& other){}Complex(const string other){}Complex& operator=(const Complex& other){}Complex(int a,int b):r(a),i(b){}Complex operator++(int){Complex temp = *this;i++, r++;return temp;}Complex& operator++(){i++, r++;return *this;}int& operator[](char c){if (c == 'r'){return r;}if (c == 'i'){return i;}}explicit operator float(){return sqrt(r * r + i * i);}
private:int r, i;
};int main()
{Complex a,b;a = b++;a = ++b;a['r'] = 1;a['i'] = 2;a = a + b;float f = static_cast<float>(a);float f = (float)a;//cout << a << b << endl;//cin>>a>>breturn 0;
}
static_cast<>()
dynamic_cast<>()
greater<>()
typeid()
[]() {}
copy---ostream_iterator<>()
accumulate(, , 0)
generate_n
back_inserter(vc)//往谁里面插入
vector<>::iterator itr 
auto itr=li.begin()
explicit
cosnt & operator

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