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来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 324 行 · 第 1/5 页

<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">string Text = </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">@&quot;This comprehensive compendium provides a broad and thorough investigation of all</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">aspects of programming with ASP.NET. Entirely revised and updated for the 1.1 </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">Release of .NET, this book will give you the information you need to master ASP.NET</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">and build a dynamic, successful, enterprise Web application.&quot;;</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; FTEL: 21.45pt"><span style="FONT-FAMILY: 黑体">注意：</span></p>
<p class="a1" style="FTEL: 21.85pt"><span style="FONT-FAMILY: 楷体_GB2312; LETTER-SPACING: 0.1pt">不考虑换行，则上面的表达式是合法的</span><span lang="EN-US" style="LETTER-SPACING: 0.1pt">C#</span><span style="FONT-FAMILY: 楷体_GB2312; LETTER-SPACING: 0.1pt">代码</span><span style="FONT-FAMILY: 楷体_GB2312; LETTER-SPACING: -1pt">&mdash;&mdash;</span><span style="LETTER-SPACING: -1pt"> </span><span style="FONT-FAMILY: 楷体_GB2312; LETTER-SPACING: 0.1pt">说明了使用字符串时应在前面加上符号</span><span lang="EN-US" style="LETTER-SPACING: 0.1pt">@</span><span style="FONT-FAMILY: 楷体_GB2312; LETTER-SPACING: 0.1pt">。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">我们把这个文本称为输入字符串。为了说明正则表达式</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">类，我们先进行一次纯文本的搜索，这次搜索不带任何转义序列或正则表达式命令。假定要查找所有的字符串</span><span lang="EN-US">ion</span><span style="FONT-FAMILY: 宋体">，把这个搜索字符串称为模式。使用正则表达式和上面声明的变量</span><span lang="EN-US">Text</span><span style="FONT-FAMILY: 宋体">，编写出下面的代码：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">string Pattern = &quot;ion&quot;;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">MatchCollection Matches = Regex.Matches(Text, Pattern,</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; RegexOptions.IgnoreCase |</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RegexOptions.ExplicitCapture);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">foreach (Match NextMatch in Matches)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US">&nbsp;&nbsp; Console.WriteLine(NextMatch.Index);</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">在这段代码中，使用了</span><span lang="EN-US">System.Text.RegularExpressions</span><span style="FONT-FAMILY: 宋体">命名空间中</span><span lang="EN-US">Regex</span><span style="FONT-FAMILY: 宋体">类的静态方法</span><span lang="EN-US">Matches()</span><span style="FONT-FAMILY: 宋体">。这个方法的参数是一些输入文本、一个模式和</span><span lang="EN-US">RegexOptions</span><span style="FONT-FAMILY: 宋体">枚举中的一组可选标志。在本例中，指定所有的搜索都不应区分大小写。另一个标记</span><span lang="EN-US">ExplicitCapture </span><span style="FONT-FAMILY: 宋体">改变了收集匹配的方式，对于本例，这样可以使搜索的效率更高，其原因详见后面的内容</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">尽管它还有这里没有介绍的其他用法</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。</span><span lang="EN-US">Matches()</span><span style="FONT-FAMILY: 宋体">返回</span><span lang="EN-US">MatchCollections</span><span style="FONT-FAMILY: 宋体">对象的引用。<span style="LETTER-SPACING: -0.2pt">匹配是一个技术术语，表示表达式中模式实例的查找结果，用</span></span><span lang="EN-US" style="LETTER-SPACING: -0.2pt">System.Text.RegularExpressions</span><span lang="EN-US">.Match</span><span style="FONT-FAMILY: 宋体">来代表。因此，我们返回一个包含所有匹配的</span><span lang="EN-US">MatchCollection</span><span style="FONT-FAMILY: 宋体">，每个匹配都用一个</span><span lang="EN-US">Match</span><span style="FONT-FAMILY: 宋体">对象来表示。在上面的代码中，只是在集合中迭代，使用</span><span lang="EN-US">Match</span><span style="FONT-FAMILY: 宋体">类的</span><span lang="EN-US">Index</span><span style="FONT-FAMILY: 宋体">属性，返回输入文本中匹配所在的索引。运行这段代码，将得到</span><span lang="EN-US">3</span><span style="FONT-FAMILY: 宋体">个匹配。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">除了一些新的</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">基类外，这些内容都不是新的。但正则表达式的功能主要取决于模式字符串。原因是模式字符串不仅仅包含纯文本。如前所述，它还可以包含元字符和转义序列，其中元字符是给出命令的特定字符，而转义序列的工作方式与</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">的转义序列相同，它们都是以反斜杠</span><span lang="EN-US">\</span><span style="FONT-FAMILY: 宋体">开头的字符，具有特殊的含义。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">例如，假定要查找以</span><span lang="EN-US">n</span><span style="FONT-FAMILY: 宋体">开头的字，就可以使用转义序列</span><span lang="EN-US">\b</span><span style="FONT-FAMILY: 宋体">，它表示一个字的边界</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">字的边界是以某个字母数字表的字符开头，或者后面是一个空白字符或标点符号</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。可以编写如下代码：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><a ftel="metacharacters"></a><a ftel="escape1"></a><a ftel="slashb"><span lang="EN-US">string Pattern = @&quot;\bn&quot;;</span></a></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">MatchCollection Matches = Regex.Matches(Text, Pattern,</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; RegexOptions.IgnoreCase | </span></p>
<p class="a6" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; RegexOptions.ExplicitCapture);</span></p>
<p class="MsoNormal" style="FTEL: 0cm"><span style="FONT-FAMILY: 宋体">注意字符串前面的符号</span><span lang="EN-US">@</span><span style="FONT-FAMILY: 宋体">。要在运行时把</span><span lang="EN-US">\b</span><span style="FONT-FAMILY: 宋体">传递给</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">正则表达式引擎，反斜杠</span><span lang="EN-US">\</span><span style="FONT-FAMILY: 宋体">不应被</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">编译器解释为转义序列。如果要查找以序列</span><span lang="EN-US">ion</span><span style="FONT-FAMILY: 宋体">结尾的字，可以使用下面的代码：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">string Pattern = @&quot;ion\b&quot;;</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">如果要查找以字母</span><span lang="EN-US">a</span><span style="FONT-FAMILY: 宋体">开头，以序列</span><span lang="EN-US">ion</span><span style="FONT-FAMILY: 宋体">结尾的所有字</span><span lang="EN-US"> (</span><span style="FONT-FAMILY: 宋体">在本例中仅有一个匹配</span><span lang="EN-US">application)</span><span style="FONT-FAMILY: 宋体">就必须在上面的代码中添加一些内容。显然，我们需要一个以</span><span lang="EN-US">\ba</span><span style="FONT-FAMILY: 宋体">开头，以</span><span lang="EN-US">ion\b</span><span style="FONT-FAMILY: 宋体">结尾的模式，但中间的内容怎么办？需要告诉应用程序在</span><span lang="EN-US">a</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">ion</span><span style="FONT-FAMILY: 宋体">中间的内容可以是任意长度的任意字符，只要这些字符不是空白即可。实际上，正确的模式如下所示。</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">string Pattern = @&quot;\ba\S*ion\b&quot;;</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">使用正则表达式要习惯的一点是，对像这样怪异的字符序列见怪不怪。但这个序列的工作是非常逻辑化的。转义序列</span><span lang="EN-US">\S</span><span style="FONT-FAMILY: 宋体">表示任何不是空白的字符。</span><span lang="EN-US">*</span><span style="FONT-FAMILY: 宋体">称为数量词，其含义是前面的字符可以重复任意次，包括</span><span lang="EN-US">0</span><span style="FONT-FAMILY: 宋体">次。序列</span><span lang="EN-US">\S*</span><span style="FONT-FAMILY: 宋体">表示任意个不是空白的字符。因此，上面的模式匹配于以</span><span lang="EN-US">a</span><span style="FONT-FAMILY: 宋体">开头，以</span><span lang="EN-US">ion</span><span style="FONT-FAMILY: 宋体">结尾的任何单词。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt; TEXT-ALIGN: left" align="left"><span style="FONT-FAMILY: 宋体">表</span><span lang="EN-US">8-4</span><span style="FONT-FAMILY: 宋体">是可以使用的一些主要的特定字符或转义序列，但这个表并不完整，要查看完整的列表请参考</span><span lang="EN-US">MSDN</span><span style="FONT-FAMILY: 宋体">文档。</span></p>
<p class="a5" style="MARGIN-TOP: 8.15pt"><span style="FONT-FAMILY: 黑体">表</span><span lang="EN-US">&nbsp; 8-4</span></p>
<div align="center">
<table class="MsoNormalTable" style="BORDER-TOP-STYLE: none; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none; BORDER-COLLAPSE: collapse; BORDER-BOTTOM-STYLE: none" cellspacing="0" cellpadding="0" border="1">
    <tbody>
        <tr>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 9.9pt; BORDER-LEFT-WIDTH: 1pt; BORDER-LEFT-COLOR: windowtext; PADDING-BOTTOM: 1.4pt; WIDTH: 52.3pt; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid" valign="top" width="70">
            <p class="a2" style="TEXT-JUSTIFY: inter-ideograph; MARGIN-LEFT: 9.2pt; TEXT-ALIGN: justify; FTEL: -9.2pt"><span style="FONT-FAMILY: 黑体">符</span><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">&nbsp; </span><span style="FONT-FAMILY: 黑体">号</span></p>
            </td>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 9.9pt; BORDER-LEFT-WIDTH: 1pt; BORDER-LEFT-COLOR: windowtext; PADDING-BOTTOM: 1.4pt; WIDTH: 155.15pt; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid" valign="top" width="207">
            <p class="a2"><span style="FONT-FAMILY: 黑体">含</span><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">&nbsp; </span><span style="FONT-FAMILY: 黑体">义</span></p>
            </td>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 9.9pt; BORDER-LEFT-WIDTH: 1pt; BORDER-LEFT-COLOR: windowtext; PADDING-BOTTOM: 1.4pt; WIDTH: 55.8pt; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid" valign="top" width="74">
            <p class="a2"><span style="FONT-FAMILY: 黑体">示</span><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">&nbsp; </span><span style="FONT-FAMILY: 黑体">例</span></p>
            </td>
            <td style="PADDING-RIGHT: 9.9pt; BORDER-TOP: windowtext 1pt solid; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 173.7pt; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none" valign="top" width="232">
            <p class="a2"><span style="FONT-FAMILY: 黑体">匹配的示例</span></p>
            </td>
        </tr>
        <tr>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 52.3pt; BORDER-TOP-STYLE: none; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT-STYLE: none" valign="top" width="70">
            <p class="a4" style="MARGIN-LEFT: 0cm; TEXT-ALIGN: center" align="center"><span lang="EN-US">^</span></p>
            </td>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 155.15pt; BORDER-TOP-STYLE: none; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT-STYLE: none" valign="top" width="207">
            <p class="a4" style="MARGIN-LEFT: 0cm"><span style="FONT-FAMILY: 宋体">输入文本的开头</span></p>
            </td>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 55.8pt; BORDER-TOP-STYLE: none; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT-STYLE: none" valign="top" width="74">
            <p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">^B</span></p>
            </td>
            <td style="PADDING-RIGHT: 9.9pt; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 173.7pt; BORDER-TOP-STYLE: none; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none" valign="top" width="232">
            <p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">B</span><span style="FONT-FAMILY: 宋体">，但只能是文本中的第一个字符</span><span lang="EN-US"> </span></p>
            </td>
        </tr>
        <tr>
            <td style="BORDER-RIGHT: windowtext 1pt solid; PADDING-RIGHT: 9.9pt; PADDING-LEFT: 9.9pt; PADDING-BOTTOM: 1.4pt; WIDTH: 52.3pt; BORDER-TOP-STYLE: none; PADDING-TOP: 1.4pt; BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT-STYLE: none" valign="top" width="70">
            <p class="a4" style="MARGIN-LEFT: 0cm; TEXT-ALIGN: center" align="center"><span lang="EN-US">$</span></p>
            </td>