Python实现的用户登录系统功能示例

#!/usr/bin/env pythondb = {}def newuser():  prompt = 'login desired: '  while 1:    name = raw_input(prompt)    if db.has_key(name):      prompt = 'name taken, try another: '      continue    else:      break  pwd = raw_input('passwd: ')  db[name] = pwddef olduser():  name = raw_input('login: ')  pwd = raw_input('passwd: ')  passwd = db.get(name)  if passwd == pwd:    pass  else:    print 'login incorrect'    return  print 'welcome back', namedef showmenu():##主函数名  prompt = """(N)ew User Login(E)xisting User Login(Q)uitEnter choice: """  done = 0 ##控制循环的控制器  while not done:    chosen = 0 ##控制循环的控制器    while not chosen:      try:        choice = raw_input(prompt)[0]      except (EOFError, KeyboardInterrupt):        choice = 'q'      print '/nYou picked: [%s]' % choice      if choice not in 'neq':##非neq继续小循环        print 'invalid menu option, try again'      else:        chosen = 1 ##跳出小循环    if choice == 'q': done = 1 ##跳出大循环    if choice == 'n': newuser()    if choice == 'e': olduser()if __name__ == '__main__':  showmenu()