josansun / designpattern Goto Github PK

`// ConsoleApplication1.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include
#include
#include
#include
#include
using namespace std;

class Oper
{
public:
double getNumberA()
{
return x;
}
void setNumberA(double xx)
{
x = xx;
}
double getNumberB()
{
return y;
}
void setNumberB(double yy)
{
y = yy;
}
virtual double getResult()//使oper可实例化
{
return 0.0;
}
private:
double x;
double y;
};

class OperatorAdd :public Oper
{
public:
double getResult()
{
return getNumberA() + getNumberB();
}
};

class OperatorSub :public Oper
{
public:
double getResult()
{
return getNumberA() - getNumberB();
}
};

class OperatorMul :public Oper
{
public:
double getResult()
{
return getNumberA() * getNumberB();
}
};

class OperatorDiv :public Oper
{
public:
double getResult()
{
try
{
if (fabs(getNumberB()) < 1e-9)
{
throw overflow_error("Divide by zero exception");
}
}
catch (overflow_error& e)
{
cout << e.what() << " -> " << getNumberB() << endl;
}
return getNumberA() / getNumberB();
}
};

class OperFactory
{
public:
static Oper* createOper(char operChar)
{
//这边会报错
Oper oper;
switch (operChar)
{//这里原先用法不对，应将实例的类名放在模版中，结果显示正确
case '+':
oper = new OperatorAdd();
break;
case '-':
oper = new OperatorSub();
break;
case '':
oper = new OperatorMul();
break;
case '/':
oper = new OperatorDiv();
break;
//other operation
default:
oper = NULL;
}
return oper;
}
};

void testSimpleFactoryMode()
{
shared_ptr oper(OperFactory::createOper('+'));
oper->setNumberA(1);
oper->setNumberB(2);
double res = oper->getResult();
cout << res << endl;
}

int main()
{
testSimpleFactoryMode();
return 0;
}

`