auto save

pwd.py

+username = "python"
+userpassword = "123456"
+while True:
+    name = input("请输入用户名:")
+    password = input("请输入密码:")
+    if name == username and password == userpassword:
+        print("登录成功!")
+        break
+    if  name != username:
+        print("用户名不存在,请重新输入!")
+        continue
+    if password != userpassword:
+        print("密码输入有误,请重新输入!")
+print("欢迎来到贝尔编程!")
+