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2024年4月28日发(作者：linux虚拟机忘记登录密码怎么办)
void showMessageOne()
{
printf("This is message onen");
}
void showMessageTwo()
{
printf("This is message twon");
}
void showMessageThree()
{
printf("This is message threen");
}
int main()
{
//函数指针+std::map取代switch
typedef void (*func)();
std::map
(std::make_pair(enumOne,showMessageOne));
(std::make_pair(enumTwo,showMessageTwo));
(std::make_pair(enumThree,showMessageThree));
funcMap[enumOne]();
funcMap[enumTwo]();
funcMap[enumThree]();
return 0;
}
4.状态模式取代switch
#include
class Context;
class State
{
public:
State() {}
virtual ~State() {}
virtual void showMessage(Context *pContext) = 0;
};
class MessageOne :public State
{
public:
MessageOne() {}
~MessageOne() {}
void showMessage(Context *pContext)
{
printf("This is message onen");
}
};
class MessageTwo :public State
{
public:
MessageTwo() {}
~MessageTwo() {}
void showMessage(Context *pContext)
{
printf("This is message twon");
}
};
class MessageThree :public State
{
public:
MessageThree() {}
~MessageThree() {}
void showMessage(Context *pContext)
{
printf("This is message threen");
}
};
class Context
{
public:
Context(State *pState) : m_pState(pState) {}
void Request()
{
if (m_pState)
{
m_pState->showMessage(this);
}
}
void ChangeState(State *pState)
{
m_pState = pState;
}
private:
State *m_pState;
};
int main()
{
State *pStateA = new MessageOne();
State *pStateB = new MessageTwo();
State *pStateC = new MessageThree();
Context *pContext = new Context(pStateA);
pContext->Request();
pContext->ChangeState(pStateB);
pContext->Request();
pContext->ChangeState(pStateC);
pContext->Request();
delete pContext;
delete pStateC;
delete pStateB;
delete pStateA;
return 0;
}
5. 多态+模板取代switch
#include
enum EnumType
{
enumOne,
enumTwo,
enumThree
};
class Base
{
public:
Base() {}
virtual ~Base() {}
virtual void showMessage() {}
};
class MessageOne :public Base
{
public:
MessageOne() {}
~MessageOne() {}
void showMessage()
{
printf("This is message onen");
}
};
class MessageTwo :public Base
{
public:
MessageTwo() {}
~MessageTwo() {}
void showMessage()
{
printf("This is message twon");
}
};
class MessageThree :public Base
{
public:
MessageThree() {}
~MessageThree() {}
void showMessage()
{
printf("This is message threen");
}
};
template
void show( S shape)
{
ssage();
}
int main()
{
MessageOne shape1;
MessageTwo shape2;
MessageThree shape3;
show(shape1);
show(shape2);
show(shape3);
return 0;
}
参考：
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