csv文件中的Python用户名验证

我有一个csv文件，里面有学校作业的用户数据

我的问题是，我输入并存储在文件中的用户名与我读取数据并输入登录时输入的用户名不符

def Load(): #Loads data from the csv that can be stored in variables
  global userdata
  global user
  userdata = []
  f = open('userdata.csv','r')
  data = csv.reader(f)
  user = []
  for row in data:
      for field in row:
          user.append(field)
      userdata.append(user)
  f.close()

Load函数，用于打开文件并读取数据

def Login(): #Login function
  Load()
  print('Please now login to your account')

  x = False
  while not x:
      usernameLog = input('Please enter your username: ')

      j = len(userdata)
      for i in range(0,j):
          if usernameLog == userdata[i][0]: #Compares username to one in the csv file
            print('Username accepted')

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登录功能无法验证我输入的用户名与存储在程序中的用户名

如果您可以共享csv文件，则会很有帮助，因为该文件是在程序顶部导入的

import csv

def Load(): #Loads data from the csv that can be stored in variables

    userdata = []
    f = open('file.csv','r')
    data = csv.reader(f)
    users = []
    print(data)
    for row in data:
        for field in row:
            users.append(field)
    f.close()
    return users

def Login(): #Login function
    userdata = Load()
    print('Please now login to your account')
    x = False
    while x == False:
        usernameLog = input('Please enter your username: ')
        for i in range(len(userdata)):
            if usernameLog == userdata [i]: #Compares username to one in the csv file
                print('Username accepted')
                x = True
Login()