关于错误：error C2320: expected ':' to follow access specifier 'type'

该代码是一个简单计算器，其中包含封装，继承，和多态的思想！但是有个错误一直改不过来！请高手帮帮忙！在此谢过诸位！


#include<iostream>
using namespace std;
class Operation
{
protected:
double number1;
double number2;

public:
double Getnumber1()
{
return number1;
}
double Getnumber2()
{
return number2;
}
virtual double GetResult()
{
double result = 0;
return result;
}
};

class OperationAdd: public Operation
{
double GetResult()
{
double result = 0;
result = number1+number2;
}
};

class OperationFactory
{
public Operation * createOperate(char c)
{

Operation *oper;
switch(c)
{
case'+':
oper=new OperationAdd;
break;
//........
}
return oper;
}

};
void main()
{
int num1,num2,results=0;
char c;
cout<<"请输入两个数和操作符："<<endl;
cin>>num1>>c>>num2;
Operation *oper;
OperationFactory operaF;
oper = operaF.createOperate(c);
results=oper->GetResult();
cout<<num1<<c<<num2<<"="<<results<<endl;
}