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 replace_file(source, l_source, l_aim):
import os
with open(r'{}'.format(source), 'r', encoding='utf-8') as f,
open('.{}.swap'.format(source), 'w', encoding='utf-8') as f1:
for line in f:
print(line)
line1 = line.replace(l_source, l_aim)
f1.write(line1)
os.remove('{}'.format(source))
os.rename('.{}.swap'.format(source), '{}'.format(source))
replace_file('users.txt','1','#')
2、编写tail工具
def tail(path1):
import time
with open('{}'.format(path1),'rb') as f:
f.seek(0,2)
while True:
l = f.readline()
if l:
print(l)
else:
time.sleep(0.3)
tail('users.txt')
3、编写登录功能
def login():
user = input('请输入账号：').strip()
pwd = input('请输入密码：').strip()
with open('users.txt','r',encoding='utf-8') as f:
for line in f:
user1, pwd1 = line.strip().split(':')
if user == user1 and pwd == pwd1:
print('登陆成功')
break
else:
print('登陆失败')
login()
4、编写注册功能
def register():
user = input('请输入账号：').strip()
if user:
pwd = input('请输入密码：').strip()
pwd1 = input('请再次确认输入密码：').strip()
if pwd == pwd1:
with open('users.txt','a',encoding='utf-8') as f:
f.write('{}:{}
'.format(user,pwd))
print('注册成功')
else:
print('密码不一致')
else:
print('用户名不能为空')
register()
选做题：编写ATM程序实现下述功能，数据来源于文件db.txt
1、充值功能：用户输入充值钱数，db.txt中该账号钱数完成修改
2、转账功能：用户A向用户B转账1000元，db.txt中完成用户A账号减钱，用户B账号加钱
3、提现功能：用户输入提现金额，db.txt中该账号钱数减少
4、查询余额功能：输入账号查询余额
import os
def top_up(user_login):
money_in = input('充值金额：')
with open('db.txt', 'r', encoding='utf-8') as f,
open('.db.txt.swap', 'w', encoding='utf-8') as f1:
for line in f:
user, money = line.strip().split(':')
if user == user_login:
money = int(money)
money += int(money_in)
print('充值成功：{}'.format(money_in))
line1 = '{}:{}
'.format(user, money)
f1.write(line1)
os.remove('db.txt')
os.rename('.db.txt.swap', 'db.txt')
def transfer_money(user_source, user_aim):
with open('db.txt', 'r', encoding='utf-8') as f,
open('.db.txt.swap', 'w', encoding='utf-8') as f1:
for ll in f:
user_l, money1000 = ll.strip().split(':')
if user_aim == user_l:
money = input('转账金额：')
f.seek(0)
l = f.readlines()
f.seek(0)
for line in f:
user, money1 = line.strip().split(':')
money1 = int(money1)
money = int(money)
if user == user_source:
if money > money1:
print('没那么多钱')
else:
money1 -= int(money)
if user == user_aim:
for i in l:
user5, money5 = i.strip().split(':')
if user5 == user_source:
if int(money5) > money:
money1 = int(money1)
money1 += int(money)
f1.write('{}:{}
'.format(user, money1))
break
else:
print('没有这个用户哦')
return
os.remove('db.txt')
os.rename('.db.txt.swap', 'db.txt')
def money_out(user):
money = input('提现金额：').strip()
with open('db.txt','r',encoding='utf-8') as f,
open('.db.txt.swap','w',encoding='utf-8') as f1:
for line in f:
user1, money1 = line.strip().split(':')
if user == user1:
money1 = int(money1)
if int(money) > money1:
print('没那么多钱')
else:
money1 -= int(money)
print('提现成功：{}'.format(money))
line1 = '{}:{}
'.format(user1,money1)
f1.write(line1)
os.remove('db.txt')
os.rename('.db.txt.swap','db.txt')
def look_at_it(user):
with open('db.txt','r',encoding='utf-8') as f:
for line in f:
user1, money = line.strip().split(':')
if user == user1:
print('余额:{}'.format(money))
# 选做题中的选做题：登录功能
# 用户登录成功后，内存中记录下该状态，上述功能以当前登录状态为准，必须先登录才能操作
def log_in():
user = input('请输入账号：').strip()
with open('users.txt','r',encoding='utf-8') as f:
for line in f:
user1, pwd1 = line.strip().split(':')
if user == user1:
pwd = input('请输入密码：').strip()
if pwd == pwd1:
print('登陆成功')
return True,user
else:
print('登陆失败')
break
else:
print('没有这个用户哦')
return 0,0
if __name__ == '__main__':
tag = [False,]
while True:
tag = log_in()
user = tag[1]
if tag[0]:
break
while tag[0]:
l = ['充值','转账','提现','查询余额','退出']
print('''===========================
0 {}
1 {}
2 {}
3 {}
4 {}
==========================='''.format(l[0],l[1],l[2],l[3],l[4]))
pwd = input('请输入命令：').strip()
if pwd.isdigit():
if pwd == '0':
top_up(user)
if pwd == '1':
user_aim = input('你想转给谁：').strip()
transfer_money(user,user_aim)
if pwd == '2':
money_out(user)
if pwd == '3':
look_at_it(user)
if pwd == '4':
break