#include<stdio.h>
#include<string.h>
#include<ctype.h>
void main()
{
     char array[50];
     int n,i,j=0,flag=0;
     scanf("%d",&n);
     for(i=0;i<n;i++)
     {
         scanf("%s",array);
    if(isalpha(array[0])||array[0]=='_')
         {
         flag=1;
         for(j=1;j<strlen(array)&&flag;j++)
         {
              if(!isalnum(array[j])&&array[j]!='_')
              {
               flag=0;
       break;
               }   
         }
         }
         if(flag)
         printf("yes\n");
         else
         printf("no\n");
     }
}

哈哈，我用的手机的c4droid.还是去电脑上编。

编译没错，但是杭电online judge依然给wrong answer
#include<stdio.h>
#include<string.h>
#include<ctype.h>
void main()
{
     char array[50];
     int n,i,j=0,flag=0;
     scanf("%d",&n);
     for(i=0;i<n;i++)
     {
         scanf("%s",array);
    if(isalpha(array[0])||array[0]=='_')
         {
           flag=1;
           for(j=1;j<strlen(array)&&flag;j++)
           {
               if(!isalnum(array[j])&&array[j]!='_')
              {
               flag=0;
               break;
               }   
           }
         }
         if(flag)
         printf("yes\n");
         else
         printf("no\n");
     }
}