python shopping incomplete code

#shopping code
#shopping.py
#导入登录模块
import login
# shop car beginning
salary = input("请输入工资:\t")
###判断输入工资是否为整型###
if salary.isdigit():
    salary = int(salary)
else:
    print ("salary not digit")
    exit()
###打印一句牛逼的话####
welcome_msg = 'welcome to our shoping mall'
print(welcome_msg.center(50, '-'))
###商品列表####
shopcar = [
    ('Iphone', 5888),
    ('Mac Air', 8000),
    ('XiaoMi', 19.9),
    ('coffee', 30),
    ('Tesla', 8200),
    ('Bike', 700),
    ('Cloth', 200)
]
for i in enumerate(shopcar):
    index = i[0]
    product = i[1][0]
    p_salary = i[1][1]

    print (index, product, p_salary)

exit_msg = '你可以输入e或者q退出，啦啦啦'
print(exit_msg.center(50, '-'))

while True:
    num = input("\033[5;30;43mplease print bianhao:\033[0m\t")
    if num.isdigit():
        num = int(num)
        ###判断输入编号不能大于7###
        if num > 7:
            print ("输入错误，没有此编号")
            continue
            ##输入编号购买商品###
            num = input("请输入商品编号:\t")
        price = shopcar[num][1]
        price_p = shopcar[num][0]
        if salary > price:
            salary -= price
            print   ("购买成功,余额为", salary)
            print ("购买的商品为:", price_p)
        else:
            print ("余额不足，请及时充值")
            print   ("余额为", salary)
            continue
    ##exit shoping##
    elif num.isalpha():
        num = str(num)
        if num == 'e' or num == 'q':
            print   ("余额为", salary)
            bye_msg = 'next to meet you,see you'
            print(bye_msg.center(50, '-'))
            break
            # if price_p():
            #     print   ("余额为", salary)
            #     exit()
            # else:
            #     print   ("购买成功,余额为", salary)
            #     print ("购买的商品为:", price_p)
            #     bye_msg = 'next to meet you,see you'
            #     print(bye_msg.center(50, '-'))