作业第十三天文件调用

# 1、编写文件修改功能，调用函数时，传入三个参数（修改的文件路径，要修改的内容，修改后的内容）既可完成文件的修改
def file(path,old,new):
    with open(path, mode='rt', encoding='utf-8') as f:
        data = f.read()
    with open(path1, mode='wt', encoding='utf-8') as f1:
        f1.write(data.replace(old,new))
# 2、编写tail工具
import time
def tail():
    with open("access.log","rb") as f:
        f.seek(0,2)
        while True:
            line = f.readline()
            if len(line) == 0:
                time.sleep(0.2)
            else:
                print(data.decode("utf-8"))
# 3、编写登录功能
def login():
    tag = True
    while tag:
        name = input("请输入用户名:").strip()
        with open("user.txt","r",encoding="utf-8") as f:
            for line in f:
                username, password = line.strip().split(":")
                if name == username:
                    count = 0
                    while count < 3:
                        pwd = input("请输入密码:").strip()
                        if pwd == password:
                            print("登录成功。")
                            tag = False
                            break
                        else:
                            print("密码错误")
                            count +=1
                    break
            else:
                print("用户名不存在。")


# 4、编写用户注册功能
def register(username,pwd,identity):
    with open("user1.txt", "r", encoding="utf-8") as f:
        for line in f:
            if username in line:
                print("用户{}已被注册".format(username))
                break
    with open("u_db.txt","a",encoding="utf-8") as fa:
        fa.write("{}:{}:{}\n".format(username,pwd,identity))
        print("用户{}注册成功。".format(username))