Python实现ATM系统：充值、转账、提现与余额查询完整代码解析

关键业务逻辑代码节选

import os

user_staus = {'username': None}


def ad_credit(username, amount):
  """
  充值功能
  :param username:
  :param amount:
  :return:
  """
  if user_staus['username'] is None:
    login()
  with open('db.txt', 'rt', encoding='utf-8')as f1, \
      open('db.txt.swap', 'wt', encoding='utf-8')as f2:
    while True:
      cont = f1.readline()
      if len(cont) == 0:
        break
      name, remain = cont.strip().split(':')
      if username in name:
        remain = int(remain) + int(amount)
        f2.write('{}:{}\n'.format(name, remain))
        print('充值成功，{}的余额为{}'.format(username, remain))
      else:
        f2.write(cont)
  os.remove('db.txt')
  os.rename('db.txt.swap', 'db.txt')


def transfer(user_out, user_in, amount):
  '''3
  转账功能
  :param user_out:
  :param user_in:
  :param amount:
  :return:
  '''
  if user_staus['username'] is None:
    login()
  with open('db.txt', 'rt', encoding='utf-8')as f1, \
      open('db.txt.swap', 'wt', encoding='utf-8')as f2:

    userinfo = {}
    for line in f1:
      name, remind = line.strip().split(':')
      userinfo[name] = int(remind)
    if user_out not in userinfo:
      print('用户不存在')
      return
    if user_in not in userinfo:
      print('收款方不存在')
      return
    if user_out in userinfo and user_in in userinfo:
      if userinfo[user_out] >= int(amount):
        userinfo[user_out] -= int(amount)
        userinfo[user_in] += int(amount)
        print('转账成功，已成功从{}向{}汇款{}'.format(user_out, user_in, amount))
      elif userinfo[user_out] < amount:
        print('余额不足')
        return
    for name, remind in userinfo.items():
      f2.write('{}:{}\n'.format(name, remind))

  os.remove('db.txt')
  os.rename('db.txt.swap', 'db.txt')


def cashon(username, amount):
  '''
  提现功能
  :param username:
  :param amount:
  :return:
  '''
  if user_staus['username'] is None:
    login()
  with open('db.txt', 'rt', encoding='utf-8')as f1, \
      open('db.txt.swap', 'wt', encoding='utf-8')as f2:
    userinfo = {}
    for line in f1:
      name, remind = line.strip().split(':')
      userinfo[name] = int(remind)
    if username not in userinfo:
      print('用户不存在')
      return
    if username in userinfo and userinfo[username] >= int(amount):
      userinfo[username] -= int(amount)
      print('已从余额中取出{}，现余额为{}'.format(amount, userinfo[username]))
    elif userinfo[username] < amount:
      print('余额不足，提现失败')
      return
    for name, remind in userinfo.items():
      f2.write('{}:{}\n'.format(name, remind))
  os.remove('db.txt')
  os.rename('db.txt.swap', 'db.txt')


def check(username):
  '''
  余额查询功能
  :param username:
  :return:
  '''
  if user_staus['username'] is None:
    login()
  with open('db.txt', 'rt', encoding='utf-8')as f:
    userinfo = {}
    for line in f:
      name, remind = line.strip().split(':')
      userinfo[name] = remind
    if username not in userinfo:
      print('用户不存在')
      return
    if username in userinfo:
      print('当前余额为：{}'.format(userinfo[username]))


def login():
  username = input('输入用户名')
  userpassword = input('输入密码')
  with open('login.txt', 'rt', encoding='utf-8')as login_f:
    login = {}
    for line in login_f:
      name, psd = line.strip().split(':')
      login[name] = psd
      if username in login:
        if login[username] == userpassword:
          print('登陆成功')
          user_staus['username'] = username
          break
      elif username not in login:
        print('用户名不存在')
        return


def logout():
  user_staus['username'] = None
  print('已成功登出')
  return


login()
tag = True
while tag:
  cmd = input('''
  请输入你想使用的功能序号
  1：充值
  2：转账
  3：提现
  4：查询余额
  0：登出
  ''')
  if cmd == '1':
    username = input('输入用户名：')
    amount = input('输入充值金额：')
    ad_credit(username, amount)
  elif cmd == '2':
    user_out = input('请输入转账方：')
    user_in = input('请输入接收方：')
    amount = input('输入转账金额：')
    transfer(user_out, user_in, amount)
  elif cmd == '3':
    username = input('输入用户名：')
    amount = input('输入提现金额')
    cashon(username, amount)
  elif cmd == '4':
    username = input('输入用户名：')
    check(username)
  elif cmd == '0':
    logout()
    tag = False
  else:
    print('请正确输入序号')