杭电OJ2024

#include <iostream>
#include <string>
using namespace std;
int main(){
	int n;
	string s;
	cin >> n;
	cin.ignore(); //getchar();  读入后面键入的回车 
	bool flag;
	for(int i = 0; i < n; i++){
		flag = true;
		s= "";
		getline(cin, s);//C++读入带空格的字符串 ， 和上面的注释联合看 
		if(s[0] == '_' || (s[0] >= 'a' && s[0] <= 'z') || (s[0] >= 'A' && s[0] <= 'Z')){
			for(string::size_type i = 1 ; i < s.size(); i++){
				if(s[i] == '_' || (s[i] >= '0' && s[i] <= '9') || (s[i] >= 'a' && s[i] <= 'z') || (s[i] >= 'A' && s[i] <= 'Z')){
				}//如果是对的什么也不做 
				else{
					flag = false;
				}
			}
		}
		else{
			flag = false;
		}//if-(if-else)-else
		if(flag){
			cout << "yes" << endl;
		}
		else{
			cout << "no" << endl;
		}
	}
	return 0;
}