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<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> return x + y;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> public static int Main()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> int i = Add(5,10);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> Console.WriteLine(i);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> return 0;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">上述代码中包含两个类，它们都有一个</span><span lang="EN-US">Main()</span><span style="FONT-FAMILY: 宋体">方法。如果按照通常的方式编译这段代码，就会得到下述错误：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 0pt 9.95pt; TEXT-INDENT: 9.95pt"><strong><span lang="EN-US">csc MainExample.cs</span></strong></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">Microsoft (R) Visual C# .NET Compiler version 7.10.3052.4</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">for Microsoft (R) .NET Framework version 1.1.4322</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">Copyright (C) Microsoft Corporation 2001-2002. All rights reserved.</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> </span></p>
<p class="a6" style="MARGIN-LEFT: 39.65pt; TEXT-INDENT: 0cm"><span lang="EN-US">MainExample.cs(7,25): error CS0017: Program 'MainExample.exe' has more than one entry point defined: 'Wrox.ProCSharp.Basics.Client.Main()'</span></p>
<p class="a6" style="MARGIN: 0cm 0cm 8.15pt 39.65pt; TEXT-INDENT: 0cm"><span lang="EN-US">MainExample.cs(21,25): error CS0017: Program 'MainExample.exe' has more than one entry point defined: 'Wrox.ProCSharp.Basics.MathExample.Main()'</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">但是，可以使用</span><span lang="EN-US">/main</span><span style="FONT-FAMILY: 宋体">选项，其后跟</span><span lang="EN-US">Main()</span><span style="FONT-FAMILY: 宋体">方法所属类的全名</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">包括命名空间</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，显式地告诉编译器把哪个方法作为程序的入口点：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><strong><span lang="EN-US">csc MainExample.cs /main:Wrox.ProCSharp.Basics.MathExample</span></strong></p>
<h3 style="MARGIN: 8.15pt 0cm"><span lang="EN-US">2.9.2 </span><span style="FONT-FAMILY: 黑体">给</span><span lang="EN-US">Main()</span><span style="FONT-FAMILY: 黑体">方法传送参数</span></h3>
<p class="MsoNormal"><span><span style="FONT-FAMILY: 宋体">到目前为止，我们的例子只介绍了不带参数的</span><span lang="EN-US">Main()</span></span><span style="FONT-FAMILY: 宋体">方法。但在调用程序时，可以让</span><span lang="EN-US">CLR</span><span style="FONT-FAMILY: 宋体">包含一个参数，将命令行参数转送给程序。这个参数是一个字符串数组，传统称<span style="LETTER-SPACING: -1pt">为</span></span><span lang="EN-US">args(</span><span style="FONT-FAMILY: 宋体">但</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">可以接受任何名称</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。在启动程序时，可以使用这个数组，访问通过命令行传送过来的选项。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.2pt">下面的例子</span><span lang="EN-US" style="LETTER-SPACING: 0.2pt">Args</span><span lang="EN-US">Example.cs</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.2pt">是在传送给</span><span lang="EN-US" style="LETTER-SPACING: 0.2pt">Main</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.2pt">方法的字符串数组中迭代，并把每个选项的值写入控制台窗口</span><span style="FONT-FAMILY: 宋体">：</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">using System;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">namespace Wrox.ProCSharp.Basics</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> class ArgsExample</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> public static int Main(string[] args)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> for (int i = 0; i < args.Length; i++)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> Console.WriteLine(args[i]);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> return 0;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">通常使用命令行就可以编译这段代码。在运行编译好的可执行文件时，可以在程序名的后面加上参数，例如：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 0pt 9.95pt; TEXT-INDENT: 9.95pt"><span><strong><span lang="EN-US">ArgsExample /a /b /c</span></strong></span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">/a</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">/b</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">/c</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='100162746.htm'><font color='red'>2.9 Main()方法</font></a></h1>
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<div style='float:left;width:49%'>·<a href='100162743.htm'>2.6 枚举</a></div><div style='float:right;width:49%'>·<a href='100162744.htm'>2.7 数组</a></div><div style='float:left;width:49%'>·<a href='100162745.htm'>2.8 命名空间</a></div><div style='float:right;width:49%'>·<a href='100162747.htm'>2.10 有关编译C#文件的更多内容</a></div><div style='float:left;width:49%'>·<a href='100162748.htm'>2.11 控制台I/O</a></div><div style='float:right;width:49%'>·<a href='100162749.htm'>2.12 使用注释</a></div></div>
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