初学Python 练习得小程序 "购物车" 自己写得lou代码

#!/usr/bin/evn python
# -*- coding:utf-8 -*-
# Author:Li ShiLin

import copy
while True :
    str = input("请输入您的资金:")
    if str.isdigit():
        print("输入的是数字")
        str = int(str)
        break
    else :
        print("输入的不是数字")

goshop = []
while True :
    # print("资金还剩余:",str)
    shop = [[0,"iphone",5800],[1,"ipde",12000],[2,"HUAWEI P10",4000],[3,"XIAOMI",3200]]
    number = input("选择你需要购买的商品:0 iphone 1:ipde 2 HUAWEI P10 3 XIAOMI Q 退出")
    # print("输入的数字是:",number)
    # print("复制的数据",copy.copy(shop[0]))
    if number == "0" :
        pride = int(shop[0][2])
        # print(type(str))
        # print(type(pride))
        print("价格是:",pride)
        if pride > str :
            print("资金不足,不能购买")
            break
        else:
            str = str-pride
            # print("资金还剩余:",str)
            print(shop[0])
            gos = copy.copy(shop[0])
            goshop.append(gos)
    elif number == "1" :
        pride = shop[1][2]
        if pride > str :
            print("资金不足,不能购买")
            break
        else:
            str = str - pride
            print(shop[1])
            gos = copy.copy(shop[1])
            goshop.append(gos)
    elif number == "2" :
        pride = shop[2][2]
        if pride > str :
            print("资金不足无法购买!")
        else:
            str = str - pride
            print(shop[2])
            gos = copy.copy(shop[2])
            goshop.append(gos)
    elif number == "3" :
        pride = shop[3][2]
        if pride > str :
            print("资金不足无法购买!")
        else:
            str = str - pride
            print(shop[3])
            gos = copy.copy(shop[3])
            goshop.append(gos)
    elif number == "Q" or number == "q" :
        print("正在退出......")
        break
    else:
        print("输入的指令有误,请仔细检查!")

print("您购买的商品有:\n",goshop)
print("资金还剩余:",str)