auto save

diy2.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!")
-    if name!=userpassword:   
-        print("密码错误!")
+    if i>0:
+       name = input("请输入用户名:")
+       password = input("请输入密码:")
+       i-=1
+       if name == username and password == userpassword:
+           print("登录成功!")
+           break
+       if name!=username:
+           print("用户名不存在!")
+       if name!=userpassword:   
+           print("密码错误!")
+    else       
 print("欢迎来到贝尔编程!")
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