C++总结

一、类与对象

1.const 常函数，常量

#include<stdio.h>

class A{
	public:
		A( int a = 50,int data=1):b(data){//初始化表
			this->a = a;
			printf("AAAAA\n");
			}
		
		~A(){
			printf("!~~~~~~~~~\n");
		}

		void show(void) const  //常亮函数 ，不会对成员进行修改
		{
			printf("b = %d\n",b);
			printf("a = %d\n",a);//证明常量函数可以打印非常量变量
            a++;              //因为是const函数，所以无法编译通过
		}
	private:
		int a;
		const int b;
};

int main(int argc, const char *argv[])
{
	A x(2);
	x.show();

	A y(3);
	y.show();

	A z;
	z.show();
	
	return 0;
}

2.static 注意区分类与对象

vbnet 复制代码

#include<stdio.h>

class A{ //类
	public:
		static void func(void)//可以不依靠于对象而实现
		{
			printf("static \n");
		}
		static int data;
};

int A::data = 10;

int main(int argc, const char *argv[])
{
	A a;   //对象
	a.func(); //基于对象可以调用

   A::func(); //此为基于类的方式,若无static 则无法调用
	
   A x;     //对象
   x.data = 100;//基于对象的赋值
   A::data = 1000;//直接对类进行操作
   
	return 0;
}

二、普通运算符重载

vbnet 复制代码

#include<stdio.h>
#include<unistd.h>

class Timer{
	public:
		Timer()
		{
			hour = 0;
			min = 0;
			sec = 0;
		}
		~Timer()
		{
		}
		void addtimer(int sec = 1)
		{
			this->min +=(this->sec + sec)/60;
			this->sec = (this->sec + sec)%60;
		}
		void show()
		{
			printf("%2d:%2d:%2d\n",hour,min,sec);
		}


		Timer operator+(int sec)
		{
            Timer tem;
			tem.sec = this->sec + sec;  // t3 = t + 3     
			return tem;
		}

		Timer operator+(Timer &x)
		{
			Timer tem;                       //t2 = t + t1  tem代表的是t，参数中代表的是括号里面的参数
			tem.sec = sec + x.sec;
			tem.min = min + x.min;
			tem.hour = hour + x.hour;
			return tem;
		}

Timer operator++(int)   //后++
	{
		Timer tem = *this;//backup
	
		sec++;

		return tem;
	}

	Timer operator++()   //前++
	{
		sec++;
		return *this;
	}

	//若返回值是 对象，则无法被赋值
	//若返回值是引用(加上&)，则可以被赋值
	
	int &operator[](int i)
	{
      switch(i)
	  {
        case 0:
			return hour;
        case 1:
			return min;
        case 2:
			return sec;

	  }
	}

	private:
		int hour;
		int min;
		int sec;
		};

int main(int argc, const char *argv[])
{
	Timer t;
	t.addtimer(3);

	Timer t1;
	t1.addtimer(5);

	Timer t2;
	t2 = t + t1;
	t2.show();
	/*
	printf("hour:%d\n",t2[0]);
	printf("min:%d\n",t2[1]);
	printf("sec:%d\n",t2[2]);

    t2[1] = 30;

	printf("hour:%d\n",t2[0]);
	printf("min:%d\n",t2[1]);
	printf("sec:%d\n",t2[2]);
*/

	Timer t3;
	t3 = t + 3;
	t3.show();

	/*
	Timer t;
	while(1)
	{
		t.addtimer(100);
		t.show();
		sleep(1);
	}
	*/
	return 0;
}

三、特殊运算符重载

3.1赋值运算符号

vbnet 复制代码

#include<stdio.h>
#include<string.h>

class A{
	public:
		A()
		{
			printf("A()\n");
			p = new char[10];
			strcpy(p,"hello");
		}
		A(const A &x)//拷贝构造函数
		{
			printf("const A &x\n");
			p = new char[10];
			strcpy(p,x.p);
		}

		A & operator = (A &x) //赋值运算符
		{
			printf("const A &x\n");
			p = new char[10];
			strcpy(p,x.p);
		}


		~A()
		{
			printf("~A()\n");
			delete []p;
		}
	
	private:
		char *p;
};



int main(int argc, const char *argv[])
{
	A x;
	A y = x;
	 
	y = x;

	return 0;
}

3.仿函数（）

vbnet 复制代码

#include<iostream>

using namespace std;

class Converter{
	public:
		Converter(double rate)
		{
			this->rate = rate;
		}
	
		double operator()(double rmb)
		{
			return rmb*rate;
		}
	private:
		double rate;
};

int main(int argc, const char *argv[])
{
	Converter RMBtoUS(6.3);
	cout << RMBtoUS(10) << endl;
	cout << RMBtoUS(10) << endl;

	Converter RMBtoE(7.8);
	cout << RMBtoE(10) << endl;
	cout << RMBtoE(10) << endl;


	return 0;
}

四、组合与继承

4.1 组合

main.cpp

#include"arr.h"

class Stuma{
	public:
		Stuma(){
		}
		~Stuma(){}
		
		void savescore(int score)
		{
			scorearr.addtail(score);
		}

		void showscore(void)
		{
			scorearr.show();
		}
private:
		ARR scorearr; //在arr.c中已经实现了
		};

int main(int argc, const char *argv[])
{
	Stuma m;
	m.savescore(22);
	m.savescore(33);

	m.showscore();

return 0;
}

arr.cpp

#include"arr.h"
#include<stdio.h>
 void ARR::addtail(int data)
{
	this->data[tail++] = data;
}

 void ARR::show(void)
{
	int i = 0;
	for(;i<tail;i++)
		printf("%d",data[i]);
	printf("\n");
}

arr.h

#ifndef _ARR_
#define _ARR_
/*
typedef struct arr{
	int data[100];
	int tail;

	void (*addtail)(struct arr *arr,int data);
	void (*show)(struct arr *arr);
}ARR;

void init(struct arr *arr);
*/
class ARR{
	public:
		ARR():tail(0)//初始化表
	{
	}
		void addtail(int data);
		void show(void);
	private:
		int data[100];
		int tail;
};

#endif

4.2 继承

#include<iostream>

using namespace std;

class A{ //基类
	public:
		A(){}
		~A(){}
		void showx()
		{
			cout<<"xxxxxxxxx\n"<<endl;
		}
};
class AX:public A{   //  继承：派生类
	public:
		void showy()
		{
			cout<<"yyyyyyyyyyyy\n"<<endl;
		}
};
int main(int argc, const char *argv[])
{
	A a;
	a.showx();

	AX b;
	b.showx();
	b.showy();

	return 0;
}

五、多态

#include<stdio.h>

class A{
	public:
		A(){
		}
		~A(){}

		void show()  //若为 virtual void show（）;作用：派生类会覆盖基类同名的函数
		{
			cout<<"AAAAAAAAA\n"<<endl;
		}
};


class B:public A{
	public:
		void show()
		{
			cout<<"BBBBBBBBBB\n"<<endl;
		}
};

int main(int argc, const char *argv[])
{
	B b;
	B *q = &b;  //只认指针，不认对象
	A *p = &b; // 支持用基类的指针 指向派生类的地址
	
	return 0;
}

案例：计算各个周长的函数

#include<iostream>

using namespace std;
class shape{
	public:
		virtual double getC(void) = 0;
		//设为纯虚拟函数
	    //此基类主要是为了提供接口
	};
class cir:public shape{  //继承类
	public:
		cir(double ri):r(ri){}//构造函数直接赋值
			double getC(void)
		{
			return 2*3.14*r;
		}
	private:
		int r;
};
class tri:public shape{
	public:
		tri(double a,double b,double c):e1(a),e2(b),e3(c){}
		double getC(void)
		{
			return e1+e2+e3;
		}
	private:
		double e1;
		double e2;
		double e3;
};
class rec:public shape{
	public:
		rec(double e)
		{
			this->e = e;
		}
		double getC(void)
		{
			return 4*e;
		}
	private:
		double e;
};

double countC(shape *arr[],int n)
{
	double sum = 0;
	for(int i = 0;i<n;i++)
	{
		sum += arr[i]->getC();
	}
	return sum;
}
int main(int argc, const char *argv[])
{
	cir c(1);
	rec r(3);
	cir c1(2);
	tri t(3,3,3);
	shape *arr[] = {&c,&r,&c1,&t};
	cout<<"total c:"<<countC(arr,4)<<endl;

	return 0;
}

六、异常

vbnet 复制代码

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
#include<exception>

using namespace std;

class argexception:public exception{
	public:
		const char* what() const throw()//不抛异常函数
		{
			return "arg Err !";
		}
};

int myatoi(const char *str)//后面没有throw表示什么异常都可以抛
{
	if(*str <'0' || *str > '9')
		throw argexception();
	else
		return atoi(str);
}

int main(int argc, const char *argv[])
{
	try{
		int data = myatoi("asfsa");
		cout << data << endl;
	}
	catch (argexception e)
	{
		cout << e.what() <<endl;
	}


	return 0;
}

七、转换函数

7.1 自定义转换

#include<stdio.h>
#include<unistd.h>
#include<iostream>

using namespace std;

class Timer{
	public:
		Timer()
		{
			hour = 0;
			min = 0;
			sec = 0;
		}
		~Timer()
		{
		}
		void addtimer(int sec = 1)
		{
			this->min +=(this->sec + sec)/60;
			this->sec = (this->sec + sec)%60;
		}
		operator int() //自定义强转类型符
		{
			return sec + min*60 + hour *60*60;
		}

	private:
		int hour;
		int min;
		int sec;
		};

int main(int argc, const char *argv[])
{
	Timer t;
	t.addtimer(3);
	int sec = t;
	cout << sec << endl;

	return 0;
}

7.2 隐式转换

#include<iostream>
using namespace std;

class mempool{
	public:
		explicit mempool(int size){
			data = new char[size];
			cout<<"this is 隐式转换"<<endl;
		}
		~mempool()
		{
			delete []data;
		}
	private:
		char *data;
};
int main(int argc, const char *argv[])
{
	mempool a(100);
	//mempool a = 100; //此语句也会调用构造函数，为了防止隐士转换，函数前加上expiicit

	return 0;
}

八、模版

#include<stdio.h>
#include<iostream>

using namespace std;

#if 0
int add(int a,int b)
{
	return a+b;
}
double add(double a,double b)
{
	return a+b;
}
#endif

template<typename xxx>
xxx add(xxx a,xxx b)
{
	return a+b;
}
int main(int argc, const char *argv[])
{
	cout<< add(1,2)<< endl;
	cout<< add(1.1,2.3) << endl;

	return 0;
}

九、STL算法

9.1、迭代器

#include <iostream>
#include <ostream>

using namespace std;

class myList{	
	struct Node{
		Node(int x, Node *ptr=NULL):data(x), next(ptr) { }
		int data;
		Node *next;
	};
public:
	class iterator{
	public:
		iterator(Node *ptr=NULL):pos(ptr) {  }
		iterator &operator++(int)
		{
			if(NULL != pos)
				pos = pos->next;
			return *this;
		}

		int &operator*()
		{
			return pos->data;
		}
	
		bool operator!=(iterator x)
		{
			return pos != x.pos;
		}
	private:
		Node *pos;
	};

public:
	myList():head(NULL) { }
	~myList() {
		while(head)
		{
			Node *tem = head;
			head = head->next;
			delete tem;
		}
	}

	void insert_head(int data)
	{
		Node *node = new Node(data);
		node->next = head;
		head = node;
	}
	
	iterator begin()
	{
		return iterator(head);
	}
	iterator end()
	{
		return iterator(NULL);
	}


	friend ostream &operator<<(ostream &out, const myList &list);

private:
	Node *head;
};

ostream &operator<<(ostream &out, const myList &list)
{
	myList::Node *tem = list.head;
	while(tem)
	{
		out<< tem->data <<',';
		tem = tem->next;
	}
	out << endl;

	return out;

}

int main()
{
	myList list;

	list.insert_head(1);
	list.insert_head(2);
	list.insert_head(4);
	list.insert_head(3);
	
	cout << list;
	
	myList::iterator i = list.begin();
	while(i != list.end() )
	{
		cout << *i <<endl;
		i++;
	}

}

链表功能的实现

#include<iostream>
#include<ostream>

using namespace std;

class myList{
	struct Node{//struct声明的默认为public
		Node(int x,Node *ptr = NULL):data(x),next(ptr){}
		int data;
		Node *next;
	};
	public:
	myList():head(NULL){}//链表的表头初始化为null
	~myList()
	{
		while(head)
		{
			Node *tem = head;
			head = head->next;
			delete tem;
		}
	}
	void insert_head(int data)
	{
		Node *node = new Node(data);//在堆中分配这个节点并赋值
		node->next = head;
		head = node;
	}
	friend ostream &operator<<(ostream &out,const myList &list);

	private:
	Node *head;
};
//  对 << (输出字符) 的运算符重载
ostream &operator<<(ostream &out,const myList &list)
{
	myList::Node *tem = list.head;
	while(tem)
	{
		out<<tem->data<<',';
		tem = tem->next;
	}
	out << endl;
	return out;
}
int main(int argc, const char *argv[])
{
	myList list;
	list.insert_head(1);
	list.insert_head(3);
	list.insert_head(2);
	list.insert_head(5);
	cout << list;

	return 0;
}

9.2、STL容器

例：迭代器和链表算法

#include<iostream>
#include<vector>
#include<list>

using namespace std;

int main(int argc, const char *argv[])
{
#if 0
      vector<int> arr;//迭代器的使用

	  arr.push_back(1);
	  arr.push_back(2);
	  arr.push_back(3);
	  arr.push_back(4);

#endif

	  //vector<double> arr;
	  list<double> arr;
	  arr.push_back(2.3);
	  arr.push_back(2.3);
	  arr.push_back(2.3);
	  arr.push_back(2.3);

	  //vector<int>::iterator i = arr.begin();
	  //vector<double>::iterator i = arr.begin();
	  list<double>::iterator i = arr.begin();//链表的使用
	  while(i != arr.end())
	  {
		  cout<< *i<<endl;
		  i++;
	  }
	return 0;
}

注意事项：

1.类中：若出现有参数的构造函数，则需要一个无参数的构造函数

2.新对象产生一定调用了构造函数

3.构造函数：a.无参数的 b.有参数的 c.拷贝构造函数

4.静态函数：基于类而不是基于对象实现的方式

5.c++最好使用++i，少用i++

6.对象生成的时候才会调用构造函数

一、类与对象

1.const 常函数，常量

2.static 注意区分 类与对象

二、普通运算符重载

三、特殊运算符重载

3.1赋值运算符号

3.仿函数（）

四、组合与继承

4.1 组合

main.cpp

arr.cpp

arr.h

4.2 继承

五、多态

案例：计算各个周长的函数

六、异常

七、 转换函数

7.1 自定义转换

7.2 隐式转换

八、模版

九、STL算法

9.1、迭代器

链表功能的实现

9.2、STL容器

注意事项：

2.static 注意区分类与对象

七、转换函数