python-- string reversal --while, for, sliced

python notes - to reverse a string

To reverse a string --while, for, sliced

• while

  mess = "海上月是天上月，心上人是眼前人。"
  list_mess = []    #创建列表
  index = len(mess)-1
  while index >= 0 :
      list_mess.append(mess[index]) #将字符添加到列表
      index -= 1
  new_mess = ''.join(list_mess) #以空格拼接字符形成新字符串
  print(new_mess)

• for - reversed for reversing

  mess = "海上月是天上月，心上人是眼前人。"
  list_mess = []
  for i in reversed(mess):
      list_mess.append(i)
  new_mess = ''.join(list_mess)
  print(new_mess)

• for - range for reversing

  mess = "海上月是天上月，心上人是眼前人。"
  list_mess = []
  for i in range(len(mess)-1,-1,-1):
      list_mess.append(mess[i])
  new_mess = ''.join(list_mess)
  print(new_mess)

• Slice - the most simple way

  mess = "海上月是天上月，心上人是眼前人。"
  print(mess[::]) #正序
  print(mess[::-1])   #反序