python -函数

#!/usr/bin/env python
# coding:utf-8
def Username():
    username = raw_input(u"请输入账号:\n")
    return username
def Passwd():
    passwd = raw_input(u"请输入密码:\n")
    return passwd
def register(username,passwd):
    '''
    实现注册功能
    '''
    tmp = username + "|" + passwd
    f = open('login', 'w')
    f.write(tmp)


def login(username,passwd):
    '''
    登录
    :parameter username:账号
    :parameter passwd :密码
    '''
    f = open('login','r')
    for line in f:
        list =line.split('|')
        if list[0] == username and list[1] == passwd:
            return True
        else:
            return False
def info(username,passwd):
    f = open('login','r')
    for line in f:
        list = line.split("|")
    r = login(username,passwd)
    if r:
        print u'恭喜'+list[0]+u'进入系统'
    else:
        print u'登录失败'
def exit():
    import sys
    sys.exit(1)

def main():
    '''主函数'''
    while True:
        t = int(raw_input(u'1.注册 2.登录 3.退出登录\n'))
        if t == 1:
            username =Username()
            passwd = Passwd()
            register(username,passwd)
        elif t ==2:
            username = Username()
            passwd = Passwd()
            login(username,passwd)
            info(username,passwd)
        elif t ==3:
            exit()
        else:
            print u'输入错误，重新输入'
if  __name__=='__main__':
    main()