python倒排列是什么意思

print arr[::-1]

arr.reverse()

    print arr

reversed(arr)     #返回一个倒序可遍历对象，需序遍历出

arr = [1,2,3,4,3,4]

reversed_arr = []

for i in reversed(arr):

    reversed_arr.append(i)

print reversed_arr

param = 'hello'

print param[::-1]

param = 'hello'

rev_str = ''

for i in reversed(param):

    rev_str += i

print rev_str

rev_arr = []

for i in reversed(param):

    rev_arr.append(i)

print ''.join(rev_arr)