《More Effective C++》学习心得（六） auto_ptr的用法

#include<iostream>
using namespace std;
class ALA
{
public:
virtual void processAdoption()=0;
protected:
private:
};
class Puppy:public ALA
{
public:
virtual void processAdoption()
{

}
protected:
private:
};
class Kitten:public ALA
{
public:
virtual void processAdoption()
{

}
protected:
private:
};
ALA * readALA(istream &s)
{
return new Puppy;

}
void processAdoptions(istream& dataSource)
{
while (dataSource)
{
ALA *pA=readALA(dataSource);
//如果发生错误，就无法delete pA，所以需要try……catch
try
{
pA->processAdoption();
}
catch (CException* e)
{
delete pA;
throw;
}

delete pA;
}

}
void main()
{
processAdoptions(cin);
}

《More Effective C++》中关于异常的处理：

对于如果函数pA->processAdoption()发生exception。位于pA->processAdoption()之后的所有语句都会跳过，不再执行，pA就不会被删除。解决办法就是，以一个“类似指针的对象”取代pA；如此，“类似指针的对象”被自动销毁，在其destrcutor调用delete；这种对象我们称为“smart pointer”；

#include<iostream>
#include <memory>
using namespace std;
class ALA
{
public:
virtual void processAdoption()=0;
protected:
private:
};
class Puppy:public ALA
{
public:
virtual void processAdoption()
{

}
protected:
private:
};
class Kitten:public ALA
{
public:
virtual void processAdoption()
{

}
protected:
private:
};
ALA * readALA(istream &s)
{
return new Puppy;

}
void processAdoptions(istream& dataSource)
{
while (dataSource)
{
auto_ptr<ALA> pA(readALA(dataSource));
pA->processAdoption();

}

}
void main()
{
processAdoptions(cin);
}