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11.1 错误和异常处理
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C#高级编程（第3版）【全文连载】
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11.1 错误和异常处理
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2006-10-13 14:41:00
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<h1 id="divCurrentNode" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165373.htm'><font color='red'>11.1 错误和异常处理</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100165370.htm'>10.2.3 Assembly类</a></div><div style='float:right;width:49%'>·<a href='100165371.htm'>10.2.4 完成WhatsNewAttributes示例</a></div><div style='float:left;width:49%'>·<a href='100165372.htm'>10.3 小结</a></div><div style='float:right;width:49%'>·<a href='100165374.htm'>11.1.1 异常类</a></div><div style='float:left;width:49%'>·<a href='100165375.htm'>11.1.2 捕获异常(1)</a></div><div style='float:right;width:49%'>·<a href='100165376.htm'>11.1.2 捕获异常(2)</a></div></div>
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<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">错误的出现并不总是编写应用程序的人的原因，有时应用程序会因为终端用户的操作而发生错误。无论如何，我们都应预测应用程序和代码中出现的错误。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span lang="EN-US">.NET Framework</span><span style="FONT-FAMILY: 宋体">改进了处理错误的方式。</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">处理错误的机制可以为每种错误提供定制的处理，并把识别错误的代码与处理错误的代码分离开来。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">本章的主要内容如下：</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt "Times New Roman""> </span></span><span style="FONT-FAMILY: 宋体">异常类</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt "Times New Roman""> </span></span><span style="FONT-FAMILY: 宋体">使用</span><span lang="EN-US">try-catch-finally</span><span style="FONT-FAMILY: 宋体">捕获异常</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt "Times New Roman""> </span></span><span style="FONT-FAMILY: 宋体">创建用户定义的异常</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">学习完本章后，您将很好地掌握</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">应用程序中的高级异常处理技术。</span></p>
<h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815037"><span lang="EN-US">11.1 </span></a><span style="FONT-FAMILY: 楷体_GB2312">错误和异常处理</span></h3>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><a ftel="exceptions"><span style="FONT-FAMILY: 宋体">无论编码技术有多好，程序都必须能处理可能出现的错误。例如，在一些复杂的处理过程中，代码没有读取文件的许可，或者在发送网络请求时，网络可能会中断。在这种情况下，某个方法调用通常不足以返回合适的错误代码<span style="LETTER-SPACING: -1pt">——</span></span> </a><span style="FONT-FAMILY: 宋体">可能方法调用嵌套了</span><span lang="EN-US">15</span><span style="FONT-FAMILY: 宋体">级或者</span><span lang="EN-US">20</span><span style="FONT-FAMILY: 宋体">级，此时，代码需要跳过所有的</span><span lang="EN-US">15</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US">20</span><span style="FONT-FAMILY: 宋体">级方法调用，完全退出任务，整理混乱的代码。</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">语言提供了处理这种情形的绝佳工具，其机制称为异常处理。</span></p>
<p class="a3" style="MARGIN-TOP: 4.9pt; FTEL: 21.45pt"><span style="FONT-FAMILY: 黑体">注意：</span></p>
<p class="a1" style="FTEL: 21.45pt"><span style="FONT-FAMILY: 楷体_GB2312">在</span><span lang="EN-US">VB6</span><span style="FONT-FAMILY: 楷体_GB2312">中，错误处理工具的功能非常有限，主要是</span><span lang="EN-US">On Error GoTo</span><span style="FONT-FAMILY: 楷体_GB2312">语句。如果您有</span><span lang="EN-US">VB6</span><span style="FONT-FAMILY: 楷体_GB2312">的背景知识，就会发现</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">异常打开了程序中处理错误的全新世界的大门。另一方面，</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 楷体_GB2312">和</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 楷体_GB2312">开发人员会比较熟悉异常的规则，因为这些语言处理错误的方式与</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">相同。</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 楷体_GB2312">开发人员会留意异常是因为</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 楷体_GB2312">可能会因此而降低性能，但在</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">中就不是这样。在</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">代码中使用异常一般不影响性能。</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 楷体_GB2312">开发人员会发现，在</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">中处理异常非常类似于在</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 楷体_GB2312">中使用异常</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 楷体_GB2312">但语法不同</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 楷体_GB2312">。</span></p></div>
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<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165373.htm'><font color='red'>11.1 错误和异常处理</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100165370.htm'>10.2.3 Assembly类</a></div><div style='float:right;width:49%'>·<a href='100165371.htm'>10.2.4 完成WhatsNewAttributes示例</a></div><div style='float:left;width:49%'>·<a href='100165372.htm'>10.3 小结</a></div><div style='float:right;width:49%'>·<a href='100165374.htm'>11.1.1 异常类</a></div><div style='float:left;width:49%'>·<a href='100165375.htm'>11.1.2 捕获异常(1)</a></div><div style='float:right;width:49%'>·<a href='100165376.htm'>11.1.2 捕获异常(2)</a></div></div>
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