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)

 1 'Take a string and remove all leading and trailing whitespace'
 2 
 3 def newStrip(str):
 4     'delete blanks around a string'
 5     _end = len(str)
 6     _start = 0
 7     
 8     # delete the blanks at the beginning of the string
 9     for i in range(_end):
10         if str[i] != ' ':
11             _start = i
12             break              
13     else:
14         print 'invalid: The string is a blank string.'     # if the string is a 
15         _blank = True                                      # blank string
16         
17     
18     # delete the blanks in the end of the string
19     for i in range(-1, _start - _end, -1):
20         if str[i] != ' ':
21             _end = _end + i
22             break      
23     if not _blank:
24         print '-' + str[_start: _end] + '-'   # print '-' make sure the function work
25 
26 # test
27 if __name__ == '__main__':
28     newStrip(raw_input('Enter a string: '))

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