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。
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#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。
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//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
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#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
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#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
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#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
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#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);<br>
cout<<get<0>(item)<<endl;
} |