拾人牙慧，浅记一些C++的类
这两天没事又翻了翻Primer，发现自己上岁数了，记单词能力开始下降，索引把一些简单的例子记下来，把一些肥肉剔除，剩一下骨头，方便今后Ctrl+F。
在此感谢：
http://ticktick.blog.51cto.com/823160/194307/
http://www.cnblogs.com/gaojun/archive/2010/09/10/1823354.html
http://www.cnblogs.com/uniqueliu/archive/2011/08/02/2125590.html
一、类的初始化--构造函数。
#include<iostream>
#include<memory>
#include<unistd.h>
using namespace std;
class Tree
{
public:
int data;
int data_arr[3];
double hello;
//无参数构造函数
//编译系统对象分配内存空间，并自动调用该构造函数->由构造函数完成成员的初始化工作
Tree(void)
{
hello=9.823;
data=22;
}
//一般构造函数
Tree(double a)
{
hello=a;
}
//复杂构造函数
Tree(const Tree &c)
{
hello=c.hello;
}
//等号运算符重载构造函数
Tree &operator=(const Tree &rt)
{
if(this==&rt)
{
return *this;
}
this->hello=rt.hello;
this->data=rt.data;
return *this;
}
private:
int price;
int num;
};
int main()
{
//一般构造
Tree a(233.33);
cout<<a.hello<<endl;
//复杂构造
Tree b(a);
cout<<b.hello<<endl;
//等号运算构造
Tree c=a;
cout<<c.hello<<endl;
}
二、深、浅拷贝--防止DELETE二次错误。
//深拷贝和浅拷贝
#include<iostream>
#include<memory>
#include<string.h>
#include<stdio.h>
using namespace std;
class Tree
{
public:
Tree(char *pN)
{
m_pName = new char[strlen(pN) + 1];
if(m_pName)
{
strcpy(m_pName ,pN);
}
}
Tree(Tree &p)
{
m_pName=new char[strlen(p.m_pName)+ 1];
if(m_pName)
{
strcpy(m_pName ,p.m_pName);
}
}
~Tree()
{
delete m_pName;
}
private:
char *m_pName;
};
int main()
{
Tree man("lujun");
Tree woman(man);
}
三、友元---我的世界你不懂，你的世界我能懂
#include<iostream>
#include<memory>
#include<string.h>
#include<stdio.h>
using namespace std;
class TV
{
public:
friend class Control;
TV():volume(20){}
void Show(TV &t)const;
private:
int volume;
};
class Control
{
public:
bool VolumeUp(TV &t);
bool VolumeDown(TV &t);
void Show(TV &t)const;
};
bool Control::VolumeUp(TV &t)
{
t.volume++;
}
bool Control::VolumeDown(TV &t)
{
t.volume--;
}
void Control::Show(TV&t)const
{
cout<<"经遥控器调整的音量大小为："<<t.volume<<endl;
}
void TV::Show(TV&t)const
{
cout<<"TV自身音量大小为："<<t.volume<<endl;
}
int main()
{
Control c1;
TV t1;
c1.VolumeUp(t1);
c1.Show(t1);
c1.VolumeUp(t1);
c1.Show(t1);
c1.VolumeDown(t1);
c1.Show(t1);
t1.Show(t1);
}
四、基类、派生、虚、多态----剪不断理还乱
#include <iostream>
using namespace std;
//原始书籍类
class Quote
{
public:
string isbn() const;
virtual double net_price(int n) const; //返回实际销售价格
Quote(void)
{
price=9.987;
}
protected:
double price;
};
string Quote::isbn() const
{
string aa="abcd,world";
cout<<aa<<endl;
return aa;
}
double Quote::net_price(int n) const
{
cout<<n+20<<endl;
return n+20;
}
//打折书籍类
class BulkQuote:public Quote
{
public:
BulkQuote()=default;
double net_price(int n) const ; //返回改动后的价格+自动覆盖
};
double BulkQuote::net_price(int n) const
{
cout<<n+10<<endl;
cout<<"n_price="<<n*price<<endl;
return n+10;
}
void PrintAll(const Quote &book); //根据实际传的类类型，进行动态鉴别
int main()
{
Quote Father,*f;
BulkQuote Son,*s;
Father.isbn();
Father.net_price(100);
cout<<endl;
Son.isbn();
Son.net_price(100);
cout<<endl;
PrintAll(Father);
PrintAll(Son);
}
void PrintAll(const Quote &book)
{
book.net_price(1000);
};
五、类模板、容器模板--真心方便
#include <iostream>
#include <vector>
#include <list>
using namespace std;
template<typename T1,typename T2>
class Tree
{
private:
T1 I;
T2 J;
public:
Tree(T1 a,T2 b);
void show();
};
template <typename T1,typename T2>
Tree<T1,T2>::Tree(T1 a,T2 b):I(a),J(b){}
template <typename T1,typename T2>
void Tree<T1,T2>::show()
{
cout<<"I="<<I<<",J="<<J<<endl;
}
template <typename X>
void print(X v)
{
typename X::iterator itor;
for (itor = v.begin(); itor != v.end(); ++itor)
{
cout<<*itor<<endl;
}
}
int main()
{
Tree<int,int> t1(33,55);
t1.show();
Tree<int,string> t2(99,"wenzhang");
t2.show();
Tree<double,string> t3(3.414,"mayili");
t3.show();
vector<int> v1;
v1.push_back(2);
v1.push_back(33);
v1.push_back(44);
print(v1);
}
六、tuple类型--自己也能MongoDB
#include <iostream>
#include <tuple>
#include <vector>
#include <list>
using namespace std;
int main()
{
tuple<string,vector<double>,int,list<int> > aa("头条",{1.1,3.4},42,{3,4,5,6,7,9});
auto item=make_tuple("play",3,99.239);
cout<<get<0>(item)<<endl;
}