product_list=[ ('Mac',9000), ('kindle',800), ('tesla',900000), ('python book',105), ('bike',2000), ] saving=input('please input your money:') shopping_car=[] if saving.isdigit(): # 做出检验,检验输入是否为数字 # isgraph检验是否为定义字符 # isdigit检验是否为数字 saving=int(saving)