Python学习进程

1.列表&enumerate

li = ["电脑", "手机", "背包"]
for key, item in enumerate(li,1):
    print(key,item)
inp = input("输入商品编号或者商品名:")
inp_num = int(inp)
print(li[inp_num - 1])

2.写个循环

'''
i = 1
while i < 100:
    i += 1
    if i % 2 == 1:
         print(i)
'''
j = 1
sum = 0
while j < 101:
    j += 1
    s = str(j)
    temp = j % 2
    if temp == 1:
        sum = sum + j
        s = s + "+" + str(j)
    if temp == 0:
        sum = sum - j
        s = s + "-" + str(j)
#    else:
#       pass
    print(s)
print(sum)