python学习4

关于关系操作符(in, not in):

l = [1,2,3,4]

2 in l

///True

5 in l

///False

5 not in l

///True

关于连接操作符(+)：

允许将两个列表，元组，字典，字符串连接

l1 = [1,2,3,4]

l2 = [5,6,7,8]

l  = l1+l2

///l = [1,2,3,4,5,6,7,8]

l1 = (1,2,3,4)

l2 = (5,6,7,8)

l =l1 + l2

///l = (1,2,3,4,5,6,7,8)

str1 = 'str1'

str2 = 'str2'

str = str1 + str2

///str = 'str1str2'

关于*操作符：

l = [1,2,3,4]

l = l*2

///l = [1,2,3,4,1,2,3,4]

关于切片操作：

[起始位置 :终止位置但不包括它 :步长 ]

l = [1,2,3,4,5,6,7,8]

l[::2]

///[1,3,5,7]