python 記錄日志

import time
def show_info():
    print("輸入提示文字，執行相應操作，0：退出  1，查看日志")
def write_loginfo():
    '''
    將用戶名和登錄時間寫入日志
    :param username:用戶名
    '''
    with open('log.txt','a') as f:
        string = '用戶名：{} 登錄時間：{}\r'.format(username,time.strftime('%Y-%m-%d %H-%M-%S',time.localtime(time.time())))
        f.write(string)
def read_loginfo():
    '''讀取日志'''
    with open('log.txt','r') as f:
        while True:
            line = f.readline()
            if line =='':
                break
            print(line)
if __name__ == '__main__':
    username = input("請輸入用戶名:")
    while len(username) <2:
        print('用戶名不能少於2位！')
        username = input("請輸入用戶名:")
    password = input('請輸入密碼：')
    while len(password)<6:
        print("密碼不能少於6位！")
        password = input('請輸入密碼：')
    print('登錄成功')
    write_loginfo()
    show_info()
    num = int(input('輸入操作數字：'))
    while True:
        if num ==0:
            print('退出成功!')
            break
        if num ==1:
            print('查看日志')
            read_loginfo()
            show_info()
            num = int(input('輸入操作數字'))
        else:
            print('您輸入的數字錯誤!')
            show_info()
            num = int(input('輸入操作數字：'))