auto save

diy2.py

@@ -5,7 +5,10 @@ while True:
     password = input("请输入密码:")
     if name == username and password == userpassword:
         print("登录成功!")
-        break    
+        break 
+    if name != username
+        print("用户名不存在,请重新输入")
+    if password != username
     print("用户名和密码错误!请重新输入")
 print("欢迎来到贝尔编程!")