Python只讀取CSV文件的第一行

Question

我相信這很簡單，但它讓我發瘋。 代碼僅讀取 CSV 文件的第一行。 如果我在 CSV 頂部輸入名稱，它會要求輸入密碼。 如果我輸入列表中的任何其他人，它會轉到“您當前未注冊”。 我想不通為什么？

with open('members.csv', 'r') as mem_login:
    login_reader = csv.reader(mem_login)
    for row in login_reader:
        if member in row:
            password = input('Please enter password...  ').lower()
            if password in row:
                print('Welcome ' + member.capitalize() + ', login successful!')
                sys.exit()
        else:
            reg_now = input('You are not currently registered. Would you like to sign-up now? Y or N   ').lower()

Answer 1

您的else案例附加到if member in row: ，因此如果第一row不包含member ，您會立即假定它們未注冊。 Dedent 一行以將其附加到for循環，因此else塊僅在for循環運行完成而沒有break才會觸發：

# newline='' is mandatory for csv module to handle dialect's newline conventions
# mode defaults to 'r', so you don't need to use it
with open('members.csv', newline='') as mem_login:
    # Unpack to username and userpass, and test individually, 
    # so user names are not their own passwords
    for username, userpass in csv.reader(mem_login): # One-lined creation of reader since it's only needed for loop
        if member == username:
            password = input('Please enter password...  ').lower()
            if password == userpass:
                print('Welcome ' + member.capitalize() + ', login successful!')
                break  # break bypasses the for's else block
    else:
        # Only runs if break not executed
        reg_now = input('You are not currently registered. Would you like to sign-up now? Y or N   ').lower()

我做了一些其他小的修復/改進（所有評論），但最大的變化是else塊的 dedent 將它附加到for循環，而不是if 。

注意：即使經過我的更改，這也存在嚴重缺陷（無殼密碼、明文密碼），因此切勿將其用於真實用戶身份驗證。