IP判断 （C++代码）

参考代码:

#include <iostream>
#include <string>
using namespace std;
int main()
{
    string str;
    int i,tot;
    while(cin>>str){
        tot=0;
        for(i=0;i<str.size();i++){
            if(str[i]=='.'){tot=0;continue;}
            else{
                if('0'<=str[i]&&str[i]<='9')
                    tot=tot*10+str[i]-'0';
                else{cout<<'N'<<endl;break;}
                if(tot>255){cout<<'N'<<endl;break;}
            }
        }
        if(i>=str.size())cout<<'Y'<<endl;
    }
    return 0;
}