其他语句问题，tkinter，python

我的逻辑/ if/else语句似乎有问题！问题在于如果我输入了错误的密码可以说但是正确的用户名，什么都没有发生，对于学生和老师来说都是类似的，我只是不确定要改变什么。谢谢。其他语句问题，tkinter，python

错误：

File "/Users/Sebastian/Desktop/DQS/login.py", line 43, in _login_btn_clickked 
    if (student_usernames.index(username) == student_passwords.index(password)): 
ValueError: tuple.index(x): x not in tuple 



from tkinter import * 
import tkinter.messagebox as tm 


class LoginFrame(Frame): 
    def __init__(self, master): 
     super().__init__(master) 

     self.label_1 = Label(self, text="Username") 
     self.label_2 = Label(self, text="Password") 

     self.entry_1 = Entry(self) 
     self.entry_2 = Entry(self, show="*") 

     self.label_1.grid(row=0, sticky=E) 
     self.label_2.grid(row=1, sticky=E) 
     self.entry_1.grid(row=0, column=1) 
     self.entry_2.grid(row=1, column=1) 

     self.checkbox = Checkbutton(self, text="Keep me logged in") 
     self.checkbox.grid(columnspan=2) 

     self.logbtn = Button(self, text="Login", command = self._login_btn_clickked) 
     self.logbtn.grid(columnspan=2) 

     self.pack() 

    def _login_btn_clickked(self): 
     #print("Clicked") 
     username = self.entry_1.get() 
     password = self.entry_2.get() 

     #print(username, password) 

     student_usernames = ("C100", "C200", "C300") 
     student_passwords = ("PASS", "PASS1", "PASS2") 

     teacher_usernames = ("T100", "T200", "T300") 
     teacher_passwords = ("TPASS", "TPASS1", "TPASS3") 


     if username in student_usernames: 
      if (student_usernames.index(username) == student_passwords.index(password)): 
       tm.showinfo("Login info", "Welcome Student") 
      else: 
       tm.showerror("Login error", "Incorrect information") 
     elif username in teacher_usernames: 
      if (teacher_usernames.index(username) == teacher_passwords.index(password)): 
       tm.showinfo("Login info", "Welcome Teacher") 
      else: 
       tm.showerror("Login error", "Incorrect information") 
     else: 
      tm.showerror("Login error", "Incorrect information") 



root = Tk() 
lf = LoginFrame(root) 
root.mainloop()

来源

2016-04-14 user5923623

你可以发布你测试它的shell输出吗？ – Tommy

'student_passwords.index（密码）'假定''password'实际存在于'student_passwords'中。你可以使用'如果用户名在student_usernames和密码在student_passwords：'中，或者用'try/except'包围整个块， – jDo

student_passwords.index(password)假定password在student_passwords确实存在。你可以用if username in student_usernames and password in student_passwords:来代替或者用try: except ValueError:

围绕整个块。

if username in student_usernames and password in student_passwords: 
    if (student_usernames.index(username) == student_passwords.index(password)): 
     tm.showinfo("Login info", "Welcome Student") 
    else: 
     tm.showerror("Login error", "Incorrect information") 
elif username in teacher_usernames and password in teacher_passwords: 
    if (teacher_usernames.index(username) == teacher_passwords.index(password)): 
     tm.showinfo("Login info", "Welcome Teacher") 
    else: 
     tm.showerror("Login error", "Incorrect information") 
else: 
    tm.showerror("Login error", "Incorrect information")

来源

2016-04-14 20:13:33 jDo

你假设输入密码总是会在你定义为包含密码的元组之一。你可以很容易地破解这个，只需传入一个不包含在元组中的东西。你是条件中断，因为正如你在错误信息中看到的，它试图找到该值的索引，但它甚至不在元组中。因此，ValueError例外。

您需要检查密码是否在相应的学生/教师密码元组以及用户名中，然后才能检查索引。

因此，这将是if username in student_usernames and password in student_passwords:作为一个例子。

或者，你可以通过德摩根定律（S）和使用反向逻辑：

if not (username in student_usernames or password in student_passwords)

来源

2016-04-14 20:11:50 Pythonista

其他语句问题，tkinter，python

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