大一新生c++基础问题求解

#include<iostream>
int main(int argc,char**argv){
    double num1;
    double num2;
    char oper;
    std::cin>>num1;
    std::cin>>oper;
    std::cin>>num2;
    if(oper=='/'&&num2<0.0000001){
        perror("num1/num2 num2 is Zero");
        return -1;
    }
    double result=0;
    switch(oper){
        case '+':result=num1+num2;break;
        case '-':result=num1-num2;break;
        case '*':result=num1*num2;break;
        case '/':result=num1/num2;break;
        case '%' :result=num1%num2 ;break;
    }
    std::cout<<"RESULT>>"<<result<<std::endl;
    return 0;
}