str1 = 'http://www.jianshu.com/u/bd3cfc499940'
key='/u/'
print('step 2:',str1[22+len(key):])
s = "abcdefg"
print('step 3:\ns=',s)
print('s[3]:',s[3])
print('s[2:4]:',s[2:4])
print('s[:5]:',s[:5])
print('s[3:]:',s[3:])
print('s[::-1]:',s[::-1])
print('s[::2]:',s[::2])
list1 = [1,2,3,4,5,6,7]
print('step 4:\nlist1=',list1)
print('list1[3]:',list1[3])
print('list1[:5]:',list1[:5])
print('list1[3:]:',list1[3:])
print('list1[::-1]:',list1[::-1])
print('list1[::2]:',list1[::2])
运行结果
step 2: bd3cfc499940
step 3:
s= abcdefg
s[3]: d
s[2:4]: cd
s[:5]: abcde
s[3:]: defg
s[::-1]: gfedcba
s[::2]: aceg
step 4:
list1= [1, 2, 3, 4, 5, 6, 7]
list1[3]: 4
list1[:5]: [1, 2, 3, 4, 5]
list1[3:]: [4, 5, 6, 7]
list1[::-1]: [7, 6, 5, 4, 3, 2, 1]
list1[::2]: [1, 3, 5, 7]
