View Code #include " iostream " using namespace std; int main(){ int n; char ch[ 1000 ]; int i; scanf( " %d\n " , & n); // cin>>n;cout<<endl; while (n -- ) { gets(ch); int count = 0 ; if ( ! (ch[ 0 ] >= ' a ' && ch[ 0 ] <= ' z ' ) && ch[ 0 ] != ' _ ' &&! (ch[ 0 ] >= ' A ' && ch[ 0 ] <= ' Z ' )) count = 1 ; else { for (i = 0 ;i < strlen(ch);i ++ ) { if ( ! (ch[i] >= ' a ' && ch[i] <= ' z ' ) &&! (ch[i] >= ' 0 ' && ch[i] <= ' 9 ' ) && ch[i] != ' _ ' &&! (ch[i] >= ' A ' && ch[i] <= ' Z ' )) { count = 1 ; break ; } } } if (count == 0 ) cout << " yes " << endl; else cout << " no " << endl; } return 0 ;} (基础知识)
标识符：字母，数字和下划线组成，以字母或下划线开头