字符串问题python实现（四）

# -*- coding:utf-8 -*-
# 问题：将一句话里的单词进行倒置，标点符号不转换。
#      比如一句话"i come from tianjin."倒换后变成"tianjin.from come i"。
# by chasdmeng

def Strinver(string):
stra = list(string)
i = 0
j = len(stra)-1
while i < j:
temp = stra[i]
stra[i] = stra[j]
stra[j] = temp
i +=1
j -=1
i = 0
while i < len(stra):
if stra[i] != ' ':
begin = i
while i !=len(stra) and stra[i] != ' ':
i +=1
i -=1 #注意
end = i
while begin < end:
temp = stra[begin]
stra[begin] = stra[end]
stra[end] = temp
begin +=1
end -=1
i +=1 #不这样写会出现无法继续执行while循环
return ''.join(stra)
if __name__ == '__main__':
string = "i come from tianjin."
print string

print Strinver(string)