day13_文件修改与函数的定义与调用

# 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
# 方式一:# 操作系统同时打开两个文件，占用操作两个资源
import os
def file_change(src_file, old, new):
    with open(src_file,'r',encoding='utf-8') as f,open('copy.txt','w',encoding='utf-8') as w:
        for line in f:
            line.replace(old,new)
        w.write(line)

    os.rename('copy.txt',src_file)

# 方式二:操作系统只打开
def file_change2(src_file, old, new):
    list=[]
    with open(src_file,'r',encoding='utf-8') as f:
        for line in f:
            line.replace(old,new)
            list.append(line.strip())

    with open(src_file, 'w', encoding='utf-8') as w:
        for line in list:
            w.write(line)


# 2、编写tail工具
def tail_access(file_name):
    import time
    with open(f'{file_name}', mode='rb') as f:
        f.seek(0, 2)
        while True:
            line = f.readline()
            if len(line) == 0:
                time.sleep(0.3)
            else:
                print(line.decode('utf-8'))


# 3、编写登录功能
user_info={'user':None}
def login():
    user_name = input('请输入用户名：').strip()
    user_pwd = input('请输入密码：').strip()
    if user_name == 'tank' and user_pwd == '123':
        user_info['user']=user_name
        print('登录成功')
    else:
        print('登录失败')


# 4、编写注册功能
def register():
    user_name = input('请输入用户名：').strip()
    user_pwd = input('请输入密码：').strip()
    re_pwd = input('请再次输入密码：').strip()
    if user_pwd == re_pwd:
        print('注册成功')
    else:
        print('注册失败')


# ATM功能实现，数据来源db.txt
# 1.充值功能
def pay_money(username):
    dic = {}  # 用于存放用户名与金额
    with open('db.txt', 'r', encoding='utf-8') as f:
        for i in f:
            user, money = i.strip().split(':')
            dic[user] = int(money)
    if username not in dic:
        print('用户不存在，退出程序')
        return

    while True:
        money = input('请输入充值金额:')
        if not money.isdigit():
            print('请输入数字：')
            continue
        money = int(money)
        dic[username] += money

        with open('db.txt', 'w', encoding='utf-8') as w:
            for user, money in dic.items():
                w.write(f'{user}:{money}\n')
        break


pay_money('tank')


# 1.转账功能
def transfer(user_A, user_B, transfer_money):
    dic = {}  # 用于存放用户名与金额
    with open('db2.txt', 'r', encoding='utf-8') as f:
        for i in f:
            user, money = i.strip().split(':')
            dic[user] = int(money)

    if not user_info.get('user'):
        login()

    if dic[user_A] not in dic:
        print('转账用户不存在')
        return
    if dic[user_B] not in dic:
        print('收款用户不存在')
        return

    if dic.get(user_A) >= transfer_money:
        dic[user_A] -= transfer_money
        dic[user_B] += transfer_money

    with open('db2.txt', 'w', encoding='utf-8') as w:
        for user, money in dic.items():
            w.write(f'{user}:{money}\n')


# 3.提现功能
def withdraw(username, int_moeny):
    dic = {}
    with open('db3.txt', 'r', encoding='utf-8') as f:
        for i in f:
            user, money = i.strip().split(':')
            dic[user] = int(money)

    if username not in dic:
        print('用户不存在，退出程序')
        return

    if dic.get(user) >= int_moeny:
        dic[username] -= int_moeny

    with open('db3.txt', 'w', encoding='utf-8') as w:
        for user, money in dic.items():
            w.write(f'{user}:{money}\n')

# 4.查询余额
def withdraw(username):
    dic = {}
    with open('db3.txt', 'r', encoding='utf-8') as f:
        for i in f:
            user, money = i.strip().split(':')
            dic[user] = int(money)
    if username not in dic:
        print('用户不存在，退出程序')
        return

    return dic.get(username)
day13_文件修改与函数的定义与调用

目录

f.seek的应用

文件修改的两种方式

函数基本使用

homework

1.f.seek的应用

2.文件修改的两种方式

3.函数基本使用

homework

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