输入商品列表，用户输入序号，显示用户选中的商品

while 1:
    li= ["手机","电脑","鼠标垫","游艇","摩托车"]
    for i in  li:
         print('{}\t\t{}'.format(li.index(i)+1,i))
    num_of_chioce =input('请输入选择的商品序号/输入Q或者q退出程序:  ')
    if  num_of_chioce.isdigit(): #特殊字符还是数字
         num_of_chioce=int( num_of_chioce)
         if  num_of_chioce> 0 and  num_of_chioce <=len(li):
             print(li[num_of_chioce-1])
         else:print("请输入有效数字")
    elif  num_of_chioce.upper() =="Q" : break
    else:print("请输入数字")