这里尽可能的不去用语言本身提供的函数。

将string逆置

def reverse(string):

	#return string[::-1]

	reversedStr = ''

	for i in xrange(len(string) - 1, -1, -1):

		reversedStr += string[i]

	return reversedStr

单词的翻转

def reverseWords(string):

	if len( string ) <= 1: return

	split = ' '

	reversedStr = ''

	word = ''

	# reverse every word in string

	for c in string:

		if c == split:

			word = reverse(word) + split

			reversedStr += word

			word = ''

		else:

			word += c

	# the last word

	reversedStr += reverse(word)

	# reverse the whole string

	reversedStr = reverse(reversedStr)

	return reversedStr

这里没有考虑前导空格之类的复杂情况，默认string是很规整的，单词间由一个空格隔开。

字符串的左右旋转。右旋转我们将字符串后面的n个字符移到最前面。通过參数direction来差别，实參为‘l'，’L‘， ’r‘， ’R'.

'''

	@ if direction = 'l' or 'L', move n items from front to end

	@ if direction = 'r' or 'R', move n items from back to front

'''

def RotateString(string, n, direction):

	if n >= len(string) or n <= 0:

		return string

	reversedStr = ''

	leftpart = ''

	rightpart = ''

	# move last n chiracter to front

	if direction == 'r' or direction == 'R':

		n = len(string) - n

	for i in range(n):

		leftpart += string[i]

	for i in range(n, len(string)):

		rightpart += string[i]

	reversedStr += reverse(leftpart)

	reversedStr += reverse(rightpart)

	reversedStr = reverse(reversedStr)

	return reversedStr

若认为单词翻转的实现繁琐。也能够直接用语言本身提供的函数。可是不推荐。

def reverseWords(string):

	return ' '.join(string.split()[::-1])