PHP、Python 相关正则函数一点实例

当我们在做字符串处理时，如果字符串处理函数不能实现我们想要的时，我们就借助正则来帮助我们实现了。

一般使用正则的情况有：匹配、查找、分割、查找并替换，下面我们就将这几种情况分别用PHP和Python语言来实现，并做一下对比。

PHP正则采用：PCRE风格。

#1 匹配Math(并获取出结果)(注意这里是要获取出匹配结果的，与不获取结果有所不同)

 

Python：

#coding:utf-8 import re strs = '我爱P你y你t知h吗o？n哈哈fe哈' patt = re.compile(r'^.*?(\w+).*?$',re.I) print patt.match(strs).group(1) #输出 P

说明match的作用是一个匹配的过程，不是查找。这个方法并不是完全匹配，想要完全匹配，可以在表达式末尾加上边界匹配符'$'。

PHP：

php $strs = '我爱P你y你t知h吗o？n哈哈fe哈'; preg_match('/^.*?(\w+).*?$/i',$strs,$m); var_dump($m[1]);

#输出：string 'P' (length=1)

说明：preg_match()与python中的match一样，在第一次匹配后 将会停止搜索。而preg_match_all()不同于此, 它会一直搜索subject 直到到达结尾。

实际上，在PHP中正则表达式还可以这样：

preg_match('/(\w+)/',$strs,$m);

#2 搜索查找Search

Python：

patt = re.compile(r'(\w+)',re.I) print patt.search(strs).group(1) #输出 P

说明search方法一样，若查找到了就立即返回，否则一直搜索到字符串末尾，在PHP中可以使用preg_match(_all) 来实现。

PHP：

同上

#3 匹配分割

Python：

patt = re.compile(r'\w+',re.I) for i in patt.split(strs): #注意这里要使用unicode对象输出 print unicode(i,'utf-8') #以上输出 ''' 我爱 你 你 知 吗 ？ 哈哈 哈'''

在PHP中可以使用preg_split()来实现

PHP：

php $strs = '我爱P你y你t知h吗o？n哈哈fe哈'; $m = preg_split('/\w+/i',$strs); var_dump($m);

/**输出：

		<b style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">array</span></b>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  0 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;我爱&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=6)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  1 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;你&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  2 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;你&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  3 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;知&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  4 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;吗&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  5 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;？&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  6 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;哈哈&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=6)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  7 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;哈&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=3)</span></i>

**/

#4 搜索查找所有结果(ALL)

Python：

print patt.findall(strs) #输出 ['P', 'y', 't', 'h', 'o', 'n', 'fe']

在PHP中可使用preg_match_all() 来实现

PHP：

php $strs = '我爱P你y你t知h吗o？n哈哈fe哈'; preg_match_all('/(\w+)/i',$strs,$m); var_dump($m);

/**

			<b style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">array</span></b>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  0 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">    </span><b style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">array</span></b>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      0 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;P&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      1 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;y&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      2 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;t&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      3 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;h&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      4 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;o&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      5 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;n&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      6 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;fe&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=2)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">  1 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">    </span><b style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">array</span></b>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      0 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;P&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      1 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;y&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      2 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;t&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      3 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;h&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      4 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;o&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      5 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;n&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=1)</span></i>
<span class="com" style="line-height: 25px; color: rgb(136, 0, 0);">      6 </span><span class="com" style="color: rgb(136, 0, 0);">=></span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;fe&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=2)</span></i>

**/

#5 查找替换

实际上finditer()方法在python中不是查找替换，它仅是返回一个顺序访问每一个匹配结果（Match对象）的迭代器

python:

for i in patt.finditer(strs): print i.group() #以上输出 ''' P y t h o n fe '''

这和PHP中的preg_filter()有所不同，preg_filter()与preg_replace()都是执行一个正则表达式的搜索和替换。在python中正则方法中，用于查找替换的是：sub()与subn()。

需要注意的是sub()返回的一个新字符串，不是作用在原对象上。

subn()返回的是一个以“新字符串和替换的次数”组成的元组，也没有作用到原对象上。

#替换三次 print patt.sub('99',strs,3) #输出 '我爱99你99你99知h吗o？n哈哈fe哈'

print patt.subn('99',strs) #输出：是一个元组('我爱99你99你99知99吗99？99哈哈99哈',7)

替换与引用

#这里批量替换文章中的图片的路径(old_c 是文章的内容)

img_dir = 'test'

img_patt = re.compile('src=".*?/(\w+\.\w+)"')

new_c = img_patt.sub(r'src="./%s/\1"'%img_dir,old_c)

PHP：

#这里批量替换文章中的图片的路径(old_c 是文章的内容)

img_dir = 'test' img_patt = re.compile('src=".*?/(\w+\.\w+)"') new_c = img_patt.sub(r'src="./%s/\1"'%img_dir,old_c)

#输出：

		<span class="com" style="color: rgb(136, 0, 0);">string</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><span class="com" style="color: rgb(136, 0, 0);">&#39;我爱999你999你999知999吗999？999哈哈999哈&#39;</span><span class="com" style="line-height: 25px; color: rgb(136, 0, 0);"> </span><i style="line-height: 25px;"><span class="com" style="color: rgb(136, 0, 0);">(length=51)</span></i>

另注   1 对于正则的基础知识可以GOOGLE一下，Python正则的基础知识也可以GOOGLE一下。

          2 对于更多关于PHP PCRE风格的正则基础，可以参看：http://cn2.php.net/manual/zh/regexp.introduction.php

          3 另外有一点需要注意的是：对于处理字符串能用字符串函数处理的就用函数处理，千万别用正则。