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剑指Offer–042-左旋转字符串--http://blog.csdn.net/gatieme/article/details/51407858 
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‎048-不能被继承的类/README.md

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#链接
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>牛客OJ：[数字在排序数组中出现的次数](http://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2?tpId=13&tqId=11190&rp=2&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking)
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>
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>九度OJ：http://ac.jobdu.com/problem.php?pid=1349
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>
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>GitHub代码： [038-数字在排序数组中出现的次数](https://github.com/gatieme/CodingInterviews/tree/master/038-数字在排序数组中出现的次数)
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>
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>CSDN题解：[剑指Offer--038-数字在排序数组中出现的次数](http://blog.csdn.net/gatieme/article/details/51330871)
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| 牛客OJ | 九度OJ | CSDN题解 | GitHub代码 |
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| ------------- |:-------------:| -----:|
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|[038-数字在排序数组中出现的次数](http://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2?tpId=13&tqId=11190&rp=2&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking) | [1505-数字在排序数组中出现的次数](http://ac.jobdu.com/problem.php?pid=1349) | [剑指Offer--038-数字在排序数组中出现的次数](http://blog.csdn.net/gatieme/article/details/51330871) | [038-数字在排序数组中出现的次数](https://github.com/gatieme/CodingInterviews/tree/master/038-数字在排序数组中出现的次数) |
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#题意
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-------
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**题目描述**
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>统计一个数字在排序数组中出现的次数。
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#1 链接
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-------
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>>牛客OJ：[数字在排序数组中出现的次数](http://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2?tpId=13&tqId=11190&rp=2&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking)
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>
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>九度OJ：http://ac.jobdu.com/problem.php?pid=1349
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>
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>GitHub代码： [038-数字在排序数组中出现的次数](https://github.com/gatieme/CodingInterviews/tree/master/038-数字在排序数组中出现的次数)
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>
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>CSDN题解：[剑指Offer--038-数字在排序数组中出现的次数](http://blog.csdn.net/gatieme/article/details/51330871)
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| 牛客OJ | 九度OJ | CSDN题解 | GitHub代码 |
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| ------------- |:-------------:| -----:|
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|[038-数字在排序数组中出现的次数](http://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2?tpId=13&tqId=11190&rp=2&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking) | [1505-数字在排序数组中出现的次数](http://ac.jobdu.com/problem.php?pid=1349) | [剑指Offer--038-数字在排序数组中出现的次数](http://blog.csdn.net/gatieme/article/details/51330871) | [038-数字在排序数组中出现的次数](https://github.com/gatieme/CodingInterviews/tree/master/038-数字在排序数组中出现的次数) |
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#2 题意
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-------
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**题目描述**
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>设计一个不能被继承的类
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#3 分析
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-------
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首先想到的是在C++中, 子类的构造函数会自动调用父类的构造函数, 同样, 子类的析构函数也会自动调用父类的析构函数
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要想一个类不能被继承, 我们只要把它的构造函数和析构函数都定义为私有函数.
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那么当一个类试图从它那继承的时候, 必然会由于试图调用构造函数、析构函数而导致编译错误
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```cpp
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class SealedClass
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{
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private :
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SealedClass( ){ }
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~SealedClass( ){ };
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};
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```
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可是这个类的构造函数和析构函数都是私有函数了, 我们怎样才能得到该类的实例呢
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我们有很多种方法来实现类的创建
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* 定义静态函数或者静态变量来创建和释放类的实例
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* 友元函数可以访问类的私有成员
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* 友元类可以访问类的私有成员
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#4 静态的创建和释放类的实例
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-------
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##4.1 静态函数
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-------
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```cpp
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#include <iostream>
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using namespace std;
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class SealedClass
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{
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public :
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static SealedClass* GetInstance( )
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{
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return new SealedClass( );
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}
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private :
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SealedClass( ){ }
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~SealedClass( ){ };
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};
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class Base : public SealedClass
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{
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};
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int main( )
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{
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SealedClass *pb = Base::GetInstance( );
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Base base;
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return 0;
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}
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```
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##4.2 静态变量
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-------
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```cpp
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#include <iostream>
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using namespace std;
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class SealedClass
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{
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public :
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static SealedClass* GetInstance( )
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{
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if(m_sc == NULL)
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{
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m_sc = new SealedClass( );
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}
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return m_sc;
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}
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static void Destroy( )
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{
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if(m_sc != NULL)
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{
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delete m_sc;
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}
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}
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private :
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SealedClass( ){ }
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~SealedClass( ){ }
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static SealedClass *m_sc;
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};
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SealedClass* SealedClass::m_sc = NULL;
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class Base : public SealedClass
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{
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};
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int main( )
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{
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SealedClass *pb = SealedClass::GetInstance( );
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SealedClass::Destroy( );
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pb = NULL;
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//Base b; // error
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return 0;
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}
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```
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#5 友元实现
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-------
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##5.1 友元函数实现
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-------
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```cpp
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#include <iostream>
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using namespace std;
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class SealedClass
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{
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private :
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SealedClass( ){ }
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~SealedClass( ){ }
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public :
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friend SealedClass* GetInstance( );
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};
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SealedClass* GetInstance( )
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{
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return new SealedClass( );
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}
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class Base : public SealedClass
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{
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};
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int main( )
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{
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SealedClass *p = GetInstance( );
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//Base base; // error
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return 0;
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}
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```
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##5.2 友元类实现
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-------
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```cpp
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#include <iostream>
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using namespace std;
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class CNoHeritance
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{
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friend class SealedClass;
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private:
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CNoHeritance(){ }
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~CNoHeritance(){ }
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};
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class SealedClass : virtual public CNoHeritance
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{
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public:
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SealedClass( ){ }
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~SealedClass( ){ }
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};
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/*
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class Base : public SealedClass
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{
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public:
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Base():SealedClass( ){ }
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~Base(){ }
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};
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*/
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int main( )
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{
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SealedClass sc;
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//Base base;
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return 0;
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}
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```
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#6 总结
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-------
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```cpp
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#include <iostream>
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using namespace std;
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template <typename T>
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class CNoHeritance
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{
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friend T;
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private:
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CNoHeritance(){ }
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~CNoHeritance(){ }
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};
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class SealedClass : virtual public CNoHeritance<SealedClass>
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{
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public:
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SealedClass( ){ }
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~SealedClass( ){ }
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};
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/*
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class Base : public SealedClass
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{
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public:
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Base():SealedClass( ){ }
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~Base(){ }
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};
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*/
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int main( )
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{
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SealedClass sc;
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//Base base;
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return 0;
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}
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```

‎048-不能被继承的类/final.cpp

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#include <iostream>
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using namespace std;
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// 调试开关
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#define __tmain main
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#ifdef __tmain
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#define debug cout
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#else
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#define debug 0 && cout
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#endif // __tmain
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template <typename T>
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class CNoHeritance
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{
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friend T;
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private:
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CNoHeritance(){ }
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~CNoHeritance(){ }
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};
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class SealedClass : virtual public CNoHeritance<SealedClass>
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{
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public:
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SealedClass( ){ }
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~SealedClass( ){ }
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};
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/*
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class Base : public SealedClass
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{
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public:
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Base():SealedClass( ){ }
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~Base(){ }
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};
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*/
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int __tmain( )
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{
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SealedClass sc;
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//Base base;
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return 0;
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}

‎048-不能被继承的类/friend_class

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