我正在創建一個系統，它會檢查用戶是否已經申請了用戶名，但是在創建帳戶時它會詢問他們想要的用戶名，然后將其發送回選項屏幕以詢問他們是否要登錄或創建帳戶.def user_create(): f = open("users.txt", "a") unique = 0 name = input("Enter a username: ") with open("users.txt", "r") as file: file_read = csv.reader(file) filerow = 1 for row in file_read: if row[0] == name: print("This username is already taken, try another one") file.close() unique = False break else: unique = True filerow = filerow + 1 if unique == True: file.close() elif unique == False: signin1() else: pass if name.replace(" ", "").isalpha(): print("Name is valid") else: print ("Name is invalid") user_create() password = input("Enter a password: ") f.write(name+","+password+",\n") f.close() print("Account created") signin1()輸出：Enter a username: testuser1. Login2. CreateWhich one would you like to do? 接下來應該詢問用戶密碼，但它似乎只跳過了一半的代碼。所有登錄代碼：def signin1(): print ("1. Login") print ("2. Create") choice = input("Which one would you like to do? ") if choice == "1": existence = os.path.exists("users.txt") if existence == False: print("There are no authorised accounts yet created") signin1() else: mainsignin() elif choice == "2": user_create() else: print("Invaild choice") signin1() def user_create(): f = open("users.txt", "a") unique = 0 name = input("Enter a username: ") with open("users.txt", "r") as file: file_read = csv.reader(file) filerow = 1 for row in file_read: if row[0] == name: print("This username is already taken, try another one") file.close() unique = False break else: unique = True
2 回答
catspeake
TA貢獻1111條經驗 獲得超0個贊
您的問題源于這種情況：elif unique == False:
您首先將值分配0給unique，然后根據文件的內容將 aTrue或 a分配給它。False如果你的文件是空的，那么在文件循環的末尾unique仍然會有一個。0現在，這里可能令人驚訝的是它0 == False被評估為 true！這是因為0是“Falsy”。因此，當您期望代碼轉到 else 時，實際上它又回到了signin1.
為避免將來出現此類錯誤，我強烈建議使用x is Trueandx is False代替x == Trueand?x == False。我還建議您不要在同一個變量中使用不同的類型（int、bool），因為這會導致像這個這樣的事故。
最后但同樣重要的是，我建議您學習如何使用調試器。如果您逐行運行這段代碼，您會很快發現這個問題。
嚕嚕噠
TA貢獻1784條經驗 獲得超7個贊
我不確定我是否正確理解了你的問題，這個問題似乎在user_create起作用，在這個函數的最開始unique被設置為0( )，如果碰巧是空的，即使給出了唯一的用戶名也會被調用。Falseusers.txtsignin1
def user_create():
f = open("users.txt", "a")
unique = 0 # unique is set to False
name = input("Enter a username: ")
with open("users.txt", "r") as file:
file_read = csv.reader(file)
filerow = 1
for row in file_read: # if users.txt is empty, following 8 lines won't run
if row[0] == name:
print("This username is already taken, try another one")
file.close()
unique = False
break
else:
unique = True
filerow = filerow + 1
if unique == True:
file.close()
elif unique == False:
signin1() # and signin1 would be called here even if a unique username is given
else:
pass
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