[详解]Python中的字符串的strip(),lstrip(),rstrip()的含义

转自：【详解】python中字符串的strip()，lstrip()，rstrip()的含义
【问】

Hi Crifan,

我在http://bbs.csdn.net/topics/390361293
里看到抓取网易公开课的脚本,我看了下,感觉还比较简单,但是有一处不是很理解

它在 获取课程名称的时候用到以下代码,

fileName=name.contents[0].strip() .lstrip() .rstrip(‘,’) +
name.a.string.strip() .lstrip() .rstrip(‘,’)

我在网上搜了下 ,

http://www.cnblogs.com/pylemon/archive/2011/05/18/2050179.html
讲到了strip,但是不理解,

后来又去
http://docs.python.org/2/library/string.html?highlight=strip#string.lstrip
看了下,还是不理解,你能帮忙看下这个脚本吗??谢谢了!!

【解答】

1. 参考，你自己给的，python官网的解释：
   http://docs.python.org/2/library/string.html?highlight=strip#string.lstrip

string.lstrip(s[, chars])
Return a copy of the string with leading characters removed. If chars is omitted or None, whitespace characters are removed. If given and not None, chars must be a string; the characters in the string will be stripped from the beginning of the string this method is called on.

Changed in version 2.2.3: The chars parameter was added. The chars parameter cannot be passed in earlier 2.2 versions.

string.rstrip(s[, chars])
Return a copy of the string with trailing characters removed. If chars is omitted or None, whitespace characters are removed. If given and not None, chars must be a string; the characters in the string will be stripped from the end of the string this method is called on.

Changed in version 2.2.3: The chars parameter was added. The chars parameter cannot be passed in earlier 2.2 versions.

string.strip(s[, chars])
Return a copy of the string with leading and trailing characters removed. If chars is omitted or None, whitespace characters are removed. If given and not None, chars must be a string; the characters in the string will be stripped from the both ends of the string this method is called on.

Changed in version 2.2.3: The chars parameter was added. The chars parameter cannot be passed in earlier 2.2 versions.

很明显的是：
lstrip = left strip =去除（字符串）左边的=stip leading=去除（字符串）开始的
rstrip = right strip =去除（字符串）右边的=strip trailling=去除（字符串）末尾的
strip = stip left and right = 去除（字符串的）左边的和右边的=strip leading and trailing = 去除（字符串）开始的和末尾的

针对strip的详细解释，翻译过来，就是：

对于输入的字符串，去除，开始的，和，末尾的，字符；
所要去除的字符，是你通过参数chars所指定的。
如果不指定该参数，或者为None，
形式为：

someStringValue.strip()

或

someStringValue.strip(None)

或

someStringValue.strip(chars=None)

则默认为白空格Whitespace。
所谓的白空格，一般指的是：
空格本身，回车\r，换行\n，制表符\t， 换页符\f

（对应于正则表达式中的： \s == [ \r\n\t\f] ）

所以，很明显的是：

someString.strip() == someString.lstrip().rstrip()

而关于此处的：

name.contents[0].strip() .lstrip() .rstrip(‘,’)

我觉得是，其多写了个lstrip()，应该改成：

name.contents[0].strip().rstrip(‘,’)

其等价于

name.contents[0].strip(None).rstrip(‘,’)

意思是
对于name.contents[0]，
先去除首尾（即头部和尾部）的白空格（空格本身，回车\r，换行\n，制表符\t， 换页符\f ）
之后，再去除尾部的逗号’,’