SDUT ACM 实验九 C语言合法标识符

#include <stdio.h>
#include <string.h>

int main()
{
char  s[110];
int i, flag, n, j;
scanf("%d%*c", &n);
for(j = 0; j <= n - 1; j++)
{
gets(s);
flag = 0;
for(i = 0; i <= strlen(s) - 1; i++)
{
if(i == 0)
{
if((s[i] >= 'a' && s[i] <= 'z')||(s[i] >= 'A' && s[i] <= 'Z')||(s[i] == '_'))
{
flag = 1;
}
}
else
{
if((s[i] >= 'a' && s[i] <= 'z')||(s[i] >= 'A' && s[i] <= 'Z')||(s[i] == '_')||(s[i] >= '0' && s[i] <= '9'));
else
break;
}
}
if(flag == 1 && i == strlen(s))
printf("yes\n");
else
printf("no\n");
}
return 0;
}