一.简述定义函数的三种方式
1.空函数：用于占位
2.有参函数：有参数的函数
3.无参函数：没有参数的函数
二.简述函数的返回值
1.如果函数没有返回值，默认返回None
2.函数可以通过return返回出返回值
3.return可以终止函数
4.return可以返回多个值，以列表形式储存
5.内置方法
三.简述函数的参数
1.形参：一般具有描述的意义，毫无作用（定义的时候写在括号里的）
2.实参：具有实际的意义，具体的一个值（传给形参）
位置形参： 从左到右一个一个写过去，就叫做位置形参
位置实参：从左到右一个一个写过，就叫做位置实参，（有多少个位置形参，就必须有多少个位置实参，从左到右依次传值）
四.编写注册函数
def register():
username_inp = input("请输入你的用户名：")
if ':' in username_inp:
print('输入错误,我必须选中一个目标')
pswd_inp = input("请输入你的密码：")
with open('user_info.txt', 'a', encoding='utf8') as fa:
fa.write(f'{username_inp}:{pswd_inp}')
print('保存成功')
五.编写登录函数
def login():
with open('user_info.txt', 'r', encoding='utf8') as fr:
data=fr.read()
data_split=data.split(':')
username = data_split[0]
pswd = data_split[1]
username_inp=input("请输入账号")
pswd_inp=input('请输入密码')
if username == username_inp and pswd == pswd_inp:
print("wdnmd")
else:
print("wtf")
六.可仿造 https://www.cnblogs.com/nickchen121/p/11070005.html 编写购物车系统
import os #join os
product_list=[ #make a product list
['watermelon',80],
['starbucks',30],
['dogfoods',200],
['human',5],
['nitendoswitch',2400],
['shoppingcart',10],
]
shopping_cart={} #define a shoppingcart dictionary
current_userinfo={} #define current_userinfo dictionary
db_file=r'db.txt'
while True: #永久循环
print('''
press 1 to login
press 2 to register
press 3 to shopping
''')
choice=input('>>:').strip()
if choice=="1":
#1.login
tag=True
count=0
while tag:
if count==3:
print("you've tried too much please logout")
break #if you made mistakes for 3times you i'll be kicked out
uname=input('username:').strip()
pswd=input('password:').strip()#delete the blank
with open(db_file,'r',encoding='utf-8')as f:
for line in f: #reading the file in db
line = line.strip('
')
user_info=line.split(',')
uname_of_db=user_info[0]
pswd_of_db=user_info[1]
balance_of_db=int(user_info[2])
if uname==uname_of_db and pswd==pswd_of_db:
print('login succeed')
#登陆成功则经用户名和余额添加到列表
current_userinfo=[uname_of_db,balance_of_db]
print('userinfo is：',current_userinfo)
tag=False
break
else:
print('usename or password fault!')
count=+1
elif choice=='2':
uname=input('please enter username:').strip()
while True:
pswd1=input("please enter your password:").strip()
pswd2=input("please confirm your password:").strip()
if pswd2==pswd1:
break
else:
print('than was different passwords,please enter again!!!')
balance=input('please enter the money you would like to recharge:').strip()
with open(db_file,"a",encoding='utf-8')as f:
f.write('%s,%s,%s
' % (uname, pswd1, balance))
elif choice=='3':
if len(current_userinfo)==0:
print('please login first')
else:
uname_of_db=current_userinfo[0]
balance_of_db=current_userinfo[1]
print('尊敬的用户[%s] 您的余额为[%s],祝您购物愉快' % (uname_of_db, balance_of_db))
tag=True
while tag:
for index,product in enumerate(product_list):
print(index,product)
choice=input('enter the number of goods,enter q to quit>>:').strip()
if choice.isdigit():
choice=int(choice)
if choice<0 or choice>=len(product_list):continue
pname=product_list[choice][0]
pprice=product_list[choice][1]
if balance_of_db>pprice:
if pname in shopping_cart:#if you've already bought
shopping_cart[pname]['count']+=1#add one more same goods
else:
shopping_cart[pname]={
'pprice':pprice,
'count':1
}
balance_of_db-=pprice#reduce your money
current_userinfo[1]=balance_of_db
print(
"Added product " + pname +
" into shopping cart,[42;1myour current balance "
+ str(balance_of_db))
else:
print("you can't afford it,you son of bitch,product price is {price},you need {lack_price}more".format(price=pprice,lack_price=(pprice-balance_of_db)))
print(shopping_cart)
elif choice=='q':
print("""
--------------------------------已购买商品列表---------------------------------
id 商品 数量 单价 总价
""")
total_cost = 0
for i, key in enumerate(shopping_cart):
print('%22s%18s%18s%18s%18s' %
(i, key, shopping_cart[key]['count'],
shopping_cart[key]['pprice'],
shopping_cart[key]['pprice'] *
shopping_cart[key]['count']))
total_cost += shopping_cart[key][
'pprice'] * shopping_cart[key]['count']#这一段看不懂
print("""
您的总花费为: %s
您的余额为: %s
---------------------------------end---------------------------------
""" % (total_cost, balance_of_db))
while tag:
inp=input('confirm(yes/no)>>:').strip()
if inp not in ['Y', 'N', 'y', 'n', 'yes', 'no']:
continue
if inp in ['Y', 'y', 'yes']:
src_file=db_file
dst_file=r'%s.swap' % db_file
with open(src_file,'r',encoding='utf-8')as read_f,
open(dst_file,'w',encoding='utf8')as write_f:
for line in read_f:
if line.startswith(uname_of_db):
l=line.strip('
').split(',')
l[-1]=str(balance_of_db)
line=','.join(l)+'
'
write_f.write(line)
os.remove(src_file)
os.rename(dst_file,src_file)
print('shopping succeed,please waiting for delivery')
shopping_cart={}
current_userinfo=[]
tag=False
else:
print('illegal input')
elif choice =='q':
break
else:
print('illegal operate')
