python 核心编程第六章课后题自己做的答案

6–6. 字符串.创建一个 string.strip()的替代函数:接受一个字符串,去掉它前面和后面的 空格(如果使用 string.*strip()函数那本练习就没有意义了)

 'Take a string and remove all leading and trailing whitespace'

 def newStrip(str):
     'delete blanks around a string'
     _end = len(str)
     _start = 0

     # delete the blanks at the beginning of the string
     for i in range(_end):
         if str[i] != ' ':
             _start = i
             break
     else:
         print 'invalid: The string is a blank string.'     # if the string is a
         _blank = True                                      # blank string

     # delete the blanks in the end of the string
     for i in range(-1, _start - _end, -1):
         if str[i] != ' ':
             _end = _end + i
             break
     if not _blank:
         print '-' + str[_start: _end] + '-'   # print '-' make sure the function work

 # test
 if __name__ == '__main__':
     newStrip(raw_input('Enter a string: '))

6–7. 调试.看一下在例 6.5 中给出的代码(buggy.py)

(a)研究这段代码并