1个无法解析的外部命令

#include
using namespace std;
class Operations {
public:
virtual double getResult() = 0;
void setNumberA(double nA) { numberA = nA; }
void setNumberB(double nB) { numberB = nB; }
protected:
double numberA, numberB;
};
class OperationAdd :public Operations {
public:
double getResult() { return numberA + numberB; }
};
class OperationSub : public Operations {
public:
double getResult() { return numberA - numberB; }
};
class OperationMul :public Operations {
public:
double getResult() { return numberA * numberB; }
};
class OperationDiv :public Operations {
public:
double getResult() {
if (numberB == 0) throw numberB;
return numberA / numberB; }
};
int main()
{
double nA, nB;
cin >> nA >> nB;
Operations* op;
op = new OperationAdd;
op->setNumberA(nA);
op->setNumberB(nB);
cout << op->getResult() << endl;
return 0;
}

编译没有错误，你是不是把多个不同的程序放在一起编译了