C++知识点程序代码汇总

学习C++编程语言时接触到的几个知识点，分享给大家

```cpp

## 组合

#include <iostream>
#include <string>
using namespace std;
class Date
{
private:
int year;
int month;
int day;
public:
Date(){} //默认构造
Date(int y,int m,int d) //带参构造
{
year=y;
month=m;
day=d;
}
void set() //设置数据函数
{
cin>>year>>month>>day;
}
void display() //显示函数
{
cout<<year<<"年"<<month<<"月"<<day<<"日";
}
};
class Person
{
private:
int num;
char sex;
Date birthday;
char ID[19];
public:
Person(){} //默认构造
Person(int n,int y,int m,int d,char id[19],char s='m'):birthday(y,m,d)
{
num=n;
sex=s;
strcpy(ID,id); //复制函数
} //有默认值的带参构造
Person(Person& p) //拷贝构造
{
num=p.num;
sex=p.sex;
birthday=p.birthday;
strcpy(ID,p.ID);
}
void input() //输入函数
{
cout<<"请输入相应数据："<<endl;
cout<<"编号：";
cin>>num;
cout<<"性别(m/w  m为男，w为女)：";
cin>>sex;
cout<<"生日：";
birthday.set();
cout<<"身份证号：";
cin>>ID;
ID[18]='\0';
cout<<endl;
}
void output() //输出函数
{
cout<<"编号："<<num<<endl;
cout<<"性别："<<sex<<endl;
cout<<"生日：";
birthday.display();
cout<<endl;
cout<<"身份证号："<<ID<<endl;
}
~Person(){} //析构函数
};
int main()
{
Person p1;
p1.input();
p1.output();
return 0;
}



## 友元函数

#include<iostream>
using namespace std;
class  boat;
class car
{
	private:
	int weight;
	public:
	car (int j)
	{weight=j;}
	friend int getweight(car &c,boat &b);
	friend int compare(car &c,boat &b);
	int input()
	{ cout<<"输入车的质量 :"<<endl;
	cin>>weight;    }
	};
	class boat
{
	private:
	int weight;
	public:
	boat (int i)
	{weight=i;}
	int input()
	{ cout<<"输入船的质量 :"<<endl;
	cin>>weight;    }
	friend int getweight(car &c,boat &b);
	friend int compare(car &c,boat &b);
	//比较
	};
	int getweight(car &c,boat &b)
	{return c.weight+b.weight;}
	int compare(car &c,boat &b)
	{
		if(c.weight>b.weight)
		return c.weight;
		else return b.weight;
	}
	int main()
	{car c1(6);
	boat b1(5);
	c1.input();
	b1.input();
cout<<"车与船的质量和为"<<getweight(c1,b1)<<"吨"<<endl;
	cout<<"两者中最大质量为:"<<compare(c1,b1)<<"吨"<<endl;
	return 0;
	}


## 异常处理

#include<iostream>
using namespace std;
int devide(int x,int y)
{
	if(y==0)
	throw x;
	return x/y;	
}
int main()
{
	try {
cout<<"8/2="<<devide(8,2)<<endl;
cout<<"5/0="<<devide(5,0)<<endl;
cout<<"6/2="<<devide(6,2)<<endl;		
	  	}
	  	catch (int e)
	  	{
	  	cout<<e<<"  is devided"<<endl;	
	  	}
	  cout<<"is ok"<<endl;
	  return 0;
	}
//	catch处理程序的出现次序很重要，因为在一个try 块中，异常处理程序是按照它的出现次序被检查的。只要找到一个异常类型，后面的异常处理都将被忽略。例如
//catch(…)可以捕获任何异常，因此在任何情况下其它catch子句都不会被检查，所以catch(…)应放在最后


## Operator重载

#include<iostream>
using namespace std;
class complex
{
	float real;
	float image;
	public :
	complex(){}
	complex (float r,float i)
	{real=r;     image=i;}
	complex operator + (complex p)
	//运算符重载，其本身的功能不会丧失
	{return complex(real+p.real,image+p.image);
	}
	complex operator - (complex &p)
	{return complex(real-p.real,image-p.image);
	}
	complex operator * (complex &p)
	{
		complex c;
		c.real=real*p.real-image*p.image;
		c.image=image*p.real+real*p.image;
		return c;
			}
			complex operator /(complex &p)
			{
				complex c;
				int j;
				j=p.real*p.real+p.image*p.image;
			c.real=(real*p.real-(-1*image*p.image))/j;
c.image=(image*p.real+(-1*real*p.image))/j;
return c;
}/*complex operator / (complex &c2)
	{   
		int j;
	    j=c2.real*c2.real+c2.image*c2.image;
		return complex ((real*c2.real+image*c2.image)/j,(image*c2.real-real*c2.image)/j);
	}*/
	void display()
	{
		if(image>0)
		{cout<<real<<"+";
		cout<<image<<"i"<<endl;}
		if(image<0)
		{cout<<real;
		cout<<image<<"i"<<endl;}
		}
	};
	int main()
	{
		complex c1(5.0,2.0);
		complex c2(3.0,-4.0);
		complex c3;
		cout<<"c1=";
		c1.display();
		cout<<endl;
		cout<<"c2=";
		c2.display();
		cout<<endl;
		c3=c1+c2;//c1  当前对象 c2参数
		cout<<"c1+c2=";c3.display();
		cout<<endl;
		c3=c1-c2;
		cout<<"c1-c2=";c3.display();
		cout<<endl;
		c3=c1*c2;
		cout<<"c1*c2=";
		c3.display();
		cout<<endl;
		c3=c1/c2;
		//c3=c1.operator +(c2);//显式调用
		cout<<"c1/c2=";
		c3.display();
		int a=3,b=5;
		b=a+b;
		//证明+本意
		return 0;
	}