*?,+?,??
|
以上三个取第一个匹配结果（非贪婪匹配） |
<*>匹配</SPAN><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">{m,n}</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">对于前一个字符重复m到n次，{m}亦可</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">a{6}匹配6个a、a{2,4</SPAN><SPAN style="FONT-SIZE: 14px">}匹配2到4个a</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">{m,n}?</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">对于前一个字符重复m到n次，并取尽可能少</SPAN><SPAN style="FONT-SIZE: 14px"></SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">‘aaaaaa</SPAN><SPAN style="FONT-SIZE: 14px">'中a{2,4}只会匹配2个</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">"\\"</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">特殊字符转义或者特殊序列</SPAN> </TD>
<TD><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">[]</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">表示一个字符集</SPAN> </TD>
<TD><SPAN style="FONT-SIZE: 14px">[0-9]、[a-z</SPAN><SPAN style="FONT-SIZE: 14px">]、[A-Z</SPAN><SPAN style="FONT-SIZE: 14px">]、[^0]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">"|"</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">或</SPAN> </TD>
<TD><SPAN style="FONT-SIZE: 14px">A|B,或运算</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(...)</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配括号中任意表达式</SPAN> </TD>
<TD><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(?#...)</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">注释，可忽略</SPAN> </TD>
<TD><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(?=...)</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">Matches if ... matches next, but doesn't consume the string.</SPAN><SPAN style="FONT-SIZE: 14px"></SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">'(?=test)' </SPAN><SPAN style="FONT-SIZE: 14px">在hellotest中匹配hello</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(?!...)</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">Matches if ... doesn't match next.</SPAN><SPAN style="FONT-SIZE: 14px"></SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">'(?!=test)'</SPAN><SPAN style="FONT-SIZE: 14px"> </SPAN><SPAN style="FONT-SIZE: 14px">若hello后面不为test，匹配hello</SPAN><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(?<=...) </SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">Matches if preceded by ... (must be fixed length).</SPAN><SPAN style="FONT-SIZE: 14px"></SPAN><BR></TD>
<TD><SPAN style="WHITE-SPACE: normal"><SPAN style="FONT-SIZE: 14px">'(?<=hello</SPAN><SPAN style="FONT-SIZE: 14px">)test' </SPAN></SPAN><SPAN style="FONT-SIZE: 14px">在hellotest中匹配test</SPAN><BR></TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">(?<!...)</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">Matches if not preceded by ... (must be fixed length).</SPAN><SPAN style="FONT-SIZE: 14px"></SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">'(?<!hello)</SPAN><SPAN style="FONT-SIZE: 14px">test' 在hellotest中不匹配test</SPAN><BR></TD></TR></TBODY></TABLE><BR>正则表达式特殊序列表如下： <br><br>
<TABLE style="WIDTH: 60%" borderColor=#000000 cellSpacing=0 cellPadding=2 border=1>
<TBODY>
<TR>
<TD><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">特殊序列符号</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">意义</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\A</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">只在字符串开始进行匹配</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\Z</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">只在字符串结尾进行匹配</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\b</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配位于开始或结尾的空字符串</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\B</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配不位于开始或结尾的空字符串</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\d</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">相当于[0-9]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\D</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">相当于[^0-9]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\s</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配任意空白字符:[\t\n\r\r\v]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\S</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配任意非空白字符:</SPAN><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">[^\t\n\r\r\v</SPAN><SPAN style="FONT-SIZE: 14px; WHITE-SPACE: normal">]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\w</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配任意数字和字母:[a-zA-Z0-9]</SPAN> </TD></TR>
<TR>
<TD><SPAN style="FONT-SIZE: 14px">\W</SPAN><BR></TD>
<TD><SPAN style="FONT-SIZE: 14px">匹配任意非数字和字母:[^a-zA-Z0-9]</SPAN> </TD></TR></TBODY></TABLE><BR>
<P><STRONG>3.re的主要功能函数</STRONG></P>
<P> 常用的功能函数包括：compile、search、match、split、findall（finditer）、sub（subn）<BR>compile<BR>re.compile(pattern[, flags])<BR>作用：把正则表达式语法转化成正则表达式对象<BR>flags定义包括：<BR>re.I：忽略大小写<BR>re.L：表示特殊字符集 \w, \W, \b, \B, \s, \S 依赖于当前环境<BR>re.M：多行模式<BR>re.S：' . '并且包括换行符在内的任意字符（注意：' . '不包括换行符）<BR>re.U： 表示特殊字符集 \w, \W, \b, \B, \d, \D, \s, \S 依赖于 Unicode 字符属性数据库</P>
<P>search<BR>re.search(pattern, string[, flags])<BR>search (string[, pos[, endpos]])<BR>作用：在字符串中查找匹配正则表达式模式的位置，返回 MatchObject 的实例，如果没有找到匹配的位置，则返回 None。</P>
<P>match<BR>re.match(pattern, string[, flags])<BR>match(string[, pos[, endpos]])<BR>作用：match() 函数只在字符串的开始位置尝试匹配正则表达式，也就是只报告从位置 0 开始的匹配情况，而 search() 函数是扫描整个字符串来查找匹配。如果想要搜索整个字符串来寻找匹配，应当用 search()。</P>
<P><STRONG>下面是几个例子：<BR></STRONG>例：最基本的用法，通过re.RegexObject对象调用</P>
<P><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code63870"><BR>#!/usr/bin/env python<BR>import re<BR>r1 = re.compile(r'world')<BR>if r1.match('helloworld'):<BR> print 'match succeeds'<BR>else:<BR> print 'match fails'<BR>if r1.search('helloworld'):<BR> print 'search succeeds'<BR>else:<BR> print 'search fails' <BR></p></P>
<P>说明一下：r是raw(原始)的意思。因为在表示字符串中有一些转义符，如表示回车'\n'。如果要表示\表需要写为'\\'。但如果我就是需要表示一个'\'+'n'，不用r方式要写为:'\\n'。但使用r方式则为r'\n'这样清晰多了。</P>
<P>例：设置flag<BR><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code41844"><BR>#r2 = re.compile(r'n$', re.S)<BR>#r2 = re.compile('\n$', re.S)<BR>r2 = re.compile('World$', re.I)<BR>if r2.search('helloworld\n'):<BR> print 'search succeeds'<BR>else:<BR> print 'search fails' <BR></p><BR>例：直接调用<BR><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code81365"><BR>if re.search(r'abc','helloaaabcdworldn'):<BR> print 'search succeeds'<BR>else:<BR> print 'search fails' <BR></p></P>
<P>split<BR>re.split(pattern, string[, maxsplit=0, flags=0])<BR>split(string[, maxsplit=0])<BR>作用：可以将字符串匹配正则表达式的部分割开并返回一个列表<BR>例：简单分析ip</P>
<P><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code62802"><BR>#!/usr/bin/env python<BR>import re<BR>r1 = re.compile('W+')<BR>print r1.split('192.168.1.1')<BR>print re.split('(W+)', '192.168.1.1')<BR>print re.split('(W+)', '192.168.1.1', 1) <BR></p><BR>结果如下：<BR>['192', '168', '1', '1']<BR>['192', '.', '168', '.', '1', '.', '1']<BR>['192', '.', '168.1.1']</P>
<P>findall<BR>re.findall(pattern, string[, flags])<BR>findall(string[, pos[, endpos]])<BR>作用：在字符串中找到正则表达式所匹配的所有子串，并组成一个列表返回<BR>例：查找[]包括的内容（贪婪和非贪婪查找）</P>
<P><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code45049"><BR>#!/usr/bin/env python<BR>import re<BR>r1 = re.compile('([.*])')<BR>print re.findall(r1, "hello[hi]heldfsdsf[iwonder]lo")<BR>r1 = re.compile('([.*?])')<BR>print re.findall(r1, "hello[hi]heldfsdsf[iwonder]lo")<BR>print re.findall('[0-9]{2}',"fdskfj1323jfkdj")<BR>print re.findall('([0-9][a-z])',"fdskfj1323jfkdj")<BR>print re.findall('(?=www)',"afdsfwwwfkdjfsdfsdwww")<BR>print re.findall('(?<=www)',"afdsfwwwfkdjfsdfsdwww") <BR></p></P>
<P>finditer<BR>re.finditer(pattern, string[, flags])<BR>finditer(string[, pos[, endpos]])<BR>说明：和 findall 类似，在字符串中找到正则表达式所匹配的所有子串，并组成一个迭代器返回。同样 RegexObject 有：</P>
<P>sub<BR>re.sub(pattern, repl, string[, count, flags])<BR>sub(repl, string[, count=0])<BR>说明：在字符串 string 中找到匹配正则表达式 pattern 的所有子串，用另一个字符串 repl 进行替换。如果没有找到匹配 pattern 的串，则返回未被修改的 string。Repl 既可以是字符串也可以是一个函数。<BR>例：</P>
<P><div class="codetitle"><span><U></U></span> 代码如下:</p><div class="codebody" id="code71752"><BR>#!/usr/bin/env python<BR>import re<BR>p = re.compile('(one|two|three)')<BR>print p.sub('num', 'one word two words three words apple', 2) <BR></p></P>
<P>subn<BR>re.subn(pattern, repl, string[, count, flags])<BR>subn(repl, string[, count=0])</P>
<P>说明：该函数的功能和 sub() 相同，但它还返回新的字符串以及替换的次数。同样 RegexObject 有： </div>
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