#!/usr/bin/env python
#coding: utf8

import sys

mystr = []

def inputstr():
 item = raw_input('Please input your string:')
 mystr[:] = [] #清空列表
 mystr.extend(item) #將輸入的字符串拆開為一個一個字符填入列表

def printstr():
 lenth = len(mystr) - 1
 index = 0
 print "Your result is :"
 print "*****" + ''.join(mystr) + "*****"
 #.join()與之前的extend對應，將字符合并為一個元素，用''里面的內(nèi)容分割。''里面為空，則字符之間沒有間隙
 print "----------------分割符----------------"

def leftstrip(): #左剪切
 while True:
 if mystr[0] == ' ':
  mystr.pop(0)
 else:
  break
 printstr()

def rightstrip():#右剪切
 while True:
 if mystr[-1] == ' ':
  mystr.pop()
 else:
  break
 printstr()

def bothsidestrip():
 while True:
 if mystr[-1] == ' ':
  mystr.pop()
 elif mystr[0] == ' ':
  mystr.pop(0)
 else:
  break
 printstr()
#使用字典的方式，實現(xiàn)case的語法功能
CMDs = {'l':leftstrip,'r':rightstrip,'b':bothsidestrip}

def showmenu():
 prompt = """(L)eftstrip
(R)ightstrip
(B)othsidestrip
(Q)uit
Please select a choice:"""
 while True:
 choice = raw_input(prompt).lower()
 if choice not in 'lrbq':
  continue
 if choice == 'q':
  break
 inputstr()
 CMDs[choice]()

if __name__=='__main__':
 showmenu()