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C#高级编程(第三版),顶死你们。。 。up

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                <div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><p class="MsoNormal"><span style="FONT-FAMILY: 宋体">下面采用传统的方式，看看一个最简单的</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">程序<span style="LETTER-SPACING: -0.5pt">&mdash;&mdash;</span>这是一个把信息写到屏幕上的控制台应用程序。</span></p>
<h3 style="MARGIN: 8.15pt 0cm"><span lang="EN-US">2.2.1</span><span lang="EN-US">&nbsp; </span><span style="FONT-FAMILY: 黑体">代码</span></h3>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在文本编辑器</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">Notepad)</span><span style="FONT-FAMILY: 宋体">中键入下面的代码，把它保存为</span><span lang="EN-US">.cs</span><span style="FONT-FAMILY: 宋体">文件</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">First.cs)</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">&nbsp;</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">&nbsp;&nbsp; class MyFirstCSharpClass</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp; {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; static void Main()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Console.WriteLine(&quot;This isn't at all like Java!&quot;);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Console.ReadLine();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">&nbsp;&nbsp; }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">}</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 黑体">注意：</span></p>
<p class="a1" style="MARGIN-BOTTOM: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 楷体_GB2312">在后面的几章中，介绍了许多代码示例。编写</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">程序最常用的技巧是使用</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">生成一个基本项目，再把自己的代码添加进去。但是，前面几章的目的是讲授</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">语言，并使过程尽可能简单，在第</span><span lang="EN-US">12</span><span style="FONT-FAMILY: 楷体_GB2312">章之前避免涉及</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">。我们使代码显示为简单的文件，这样您就可以使用任何文本编辑器键入它们，并在命令行上对其进行编译。</span></p>
<h3 style="MARGIN: 8.15pt 0cm"><span lang="EN-US">2.2.2</span><span lang="EN-US">&nbsp; </span><span style="FONT-FAMILY: 黑体">编译并运行程序</span></h3>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体">通过对源文件运行</span><span lang="EN-US" style="COLOR: black">C#</span><span style="COLOR: black; FONT-FAMILY: 宋体">命令行编译器</span><span lang="EN-US">(csc.exe)</span><span style="FONT-FAMILY: 宋体">来编译这个程序：</span></p>
<p class="a6" style="MARGIN: 6.5pt 0cm 6.5pt 21.45pt; TEXT-INDENT: 18.45pt"><strong><span lang="EN-US">csc First.cs</span></strong></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">如果使用</span><span lang="EN-US">csc</span><span style="FONT-FAMILY: 宋体">命令在命令行上编译代码，就应注意</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">命令行工具，包括</span><span lang="EN-US">csc</span><span style="FONT-FAMILY: 宋体">，只有在设置了某些环境变量后才能使用。根据安装</span><span lang="EN-US">.NET(</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">Visual Studio .NET)</span><span style="FONT-FAMILY: 宋体">的方式，这里显示的结果可能与您机器上的结果不同。</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; TEXT-INDENT: 21.45pt"><a name="csc1"><span style="FONT-FAMILY: 黑体">注意：</span></a></p>
<p class="a1" style="MARGIN-BOTTOM: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 楷体_GB2312">如果没有设置环境变量，有两种解决方法。第一种方法是在运行</span><span lang="EN-US">csc</span><span style="FONT-FAMILY: 楷体_GB2312">之前，在命令行上运行批处理文件</span><span lang="EN-US">%Microsoft Visual Studio<em>&nbsp;</em>.NET%\Vc7\bin\vcvars32.bat</span><span style="FONT-FAMILY: 楷体_GB2312">。其中</span><span lang="EN-US">%Microsoft Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">是安装</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">的文件夹。第二种方法</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 楷体_GB2312">更简单</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 楷体_GB2312">是使用</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">命令行代替通常的命令提示窗口。</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 楷体_GB2312">命令提示在&ldquo;开始&rdquo;菜单&mdash;&ldquo;程序&rdquo;&mdash;</span><span lang="EN-US">Microsoft Visual Studio .NET 2003</span><span style="FONT-FAMILY: 楷体_GB2312">－</span><span lang="EN-US">Microsoft Visual Studio .NET Tools</span><span style="FONT-FAMILY: 楷体_GB2312">子菜单下。它只是一个命令提示窗口，打开时会自动运行</span><span lang="EN-US">vcvars32.bat</span><span style="FONT-FAMILY: 楷体_GB2312">。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">编译代码，会生成一个可执行文件</span><span lang="EN-US">First.exe</span><span style="FONT-FAMILY: 宋体">。在命令行或</span><span lang="EN-US">Windows Explorer</span><span style="FONT-FAMILY: 宋体">上，象运行任何可执行文件那样运行该文件，得到如下结果：</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 0pt 9.95pt; TEXT-INDENT: 9.95pt"><strong><span lang="EN-US">csc</span></strong><strong><span lang="EN-US"> First.cs</span></strong></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt; LINE-HEIGHT: 14pt"><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; LINE-HEIGHT: 14pt"><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; LINE-HEIGHT: 14pt"><span lang="EN-US">Copyright (C) Microsoft Corporation 2001-2002. All rights reserved.</span></p>
<p class="a6" style="MARGIN-LEFT: 9.95pt; TEXT-INDENT: 9.95pt; LINE-HEIGHT: 14pt"><strong><span lang="EN-US">First</span></strong></p>
<p class="a6" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">This isn't at all like Java!</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">这些信息也许不那么真实！这与</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">有一些非常相似的地方，但有一两个地方与</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 宋体">不同</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">如大写的</span><span lang="EN-US">Main</span><span style="FONT-FAMILY: 宋体">函数</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。下面通过这个程序快速介绍</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">程序的基本结构。</span></p>
<h3 style="MARGIN: 9.8pt 0cm"><span lang="EN-US">2.2.3</span><span lang="EN-US">&nbsp; </span><span style="FONT-FAMILY: 黑体">详细介绍</span></h3>
<p class="MsoNormal" style="LINE-HEIGHT: 18pt"><span style="FONT-FAMILY: 宋体">首先对</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">语法作几个解释。在</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">中，与其他</span><span lang="EN-US">C</span><span style="FONT-FAMILY: 宋体">风格的语言一样，每个语句都必须用一个分号</span><span lang="EN-US">(;)</span><span style="FONT-FAMILY: 宋体">结尾，语句可以写在多个代码行上，不需要使用续行字符</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">VB</span><span style="FONT-FAMILY: 宋体">中的下划线</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。用花括号</span><span lang="EN-US">({ ... })</span><span style="FONT-FAMILY: 宋体">把语句组合为块。单行注释以两个斜杠字符开头</span><span lang="EN-US">(//)</span><span style="FONT-FAMILY: 宋体">，多行注释以一个斜杠和一个星号</span><span lang="EN-US">(/*)</span><span style="FONT-FAMILY: 宋体">开头，以一个星号和一个斜杠</span><span lang="EN-US">(*/)</span><span style="FONT-FAMILY: 宋体">结尾。在这些方面，</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">与</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">一样，但与</span><span lang="EN-US">VB</span><span style="FONT-FAMILY: 宋体">不同。分号和花括号使</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">代码与</span><span lang="EN-US">VB</span><span style="FONT-FAMILY: 宋体">代码有完全不同的外观。如果您以前使用的是</span><span lang="EN-US">VB</span><span style="FONT-FAMILY: 宋体">，就应特别注意每个语句结尾的分号。对于</span><span lang="EN-US">C</span><span style="FONT-FAMILY: 宋体">风格语言的新用户，忽略该分号常常是导致编译错误的一个最主要的原因。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 18pt"><a name="using1"></a><a name="namespaces1"><span style="FONT-FAMILY: 宋体">在上面的代码示例中，前几行代码是处理命名空间</span><span lang="EN-US">(</span></a><span style="FONT-FAMILY: 宋体">如第</span><span lang="EN-US">1</span><span style="FONT-FAMILY: 宋体">章所述</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，这是把相关类组合在一起的方式。</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 宋体">开发人员应很熟悉这个概念，但对于</span><span lang="EN-US">VB6</span><span style="FONT-FAMILY: 宋体">开发人员来说是新概念。</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">命名空间与</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 宋体">命名空间或</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">的包基本相同，但</span><span lang="EN-US">VB6</span><span style="FONT-FAMILY: 宋体">中没有对应的概念。</span><span lang="EN-US">Namespace</span><span style="FONT-FAMILY: 宋体">关键字声明了应与类相关的命名空间。其后花括号中的所有代码都被认为是在这个命名空间中。编译器在</span><span lang="EN-US">using</span><span style="FONT-FAMILY: 宋体">指令指定的命名空间中查找没有在当前命名空间中定义、但在代码中引用的类。这非常类似于</span><span lang="EN-US">Java</span><span style="FONT-FAMILY: 宋体">中的</span><span lang="EN-US">import</span><span style="FONT-FAMILY: 宋体">语句和</span><span lang="EN-US">C++</span><span style="FONT-FAMILY: 宋体">中的</span><span lang="EN-US">using</span><span style="FONT-FAMILY: 宋体">命名空间语句。</span></p>
<p class="a6" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">using System;</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt; LINE-HEIGHT: 14pt"><span lang="EN-US">&nbsp;</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt; LINE-HEIGHT: 14pt"><span lang="EN-US">namespace Wrox.ProCSharp.Basics</span></p>
<p class="a6" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">{</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 17pt"><span style="FONT-FAMILY: 宋体">在</span><span lang="EN-US">First.cs</span><span style="FONT-FAMILY: 宋体">文件中使用</span><span lang="EN-US">using</span><span style="FONT-FAMILY: 宋体">指令的原因是下面要使用一个库类</span><span lang="EN-US">System.Console</span><span style="FONT-FAMILY: 宋体">。</span><span lang="EN-US">using System</span><span style="FONT-FAMILY: 宋体">指令允许把这个类简写为</span><span lang="EN-US">Console(</span><span style="FONT-FAMILY: 宋体">类似于</span><span lang="EN-US">System</span><span style="FONT-FAMILY: 宋体">命名空间中的其他类</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。标准的</span><span lang="EN-US">System</span><span style="FONT-FAMILY: 宋体">命名空间是驻留最常用的</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">类型的地方。我们用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">做的所有工作都依赖于</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">基类，认识到这一点是非常重要的；在本例中，我们使用了</span><span lang="EN-US">System</span><span style="FONT-FAMILY: 宋体">命名空间中的</span><span lang="EN-US">Console</span><span style="FONT-FAMILY: 宋体">类，以写入控制台窗口。</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; TEXT-INDENT: 21.45pt"><a name="System1"><span style="FONT-FAMILY: 黑体">注意：</span></a></p>
<p class="a1" style="MARGIN-BOTTOM: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 楷体_GB2312">几乎所有的</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">程序都使用</span><span lang="EN-US">System</span><span style="FONT-FAMILY: 楷体_GB2312">命名空间中的类，所以假定本章所有的代码文件都包含</span><span lang="EN-US">using System;</span><span style="FONT-FAMILY: 楷体_GB2312">语句。</span></p>
<p class="MsoNormal"><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">没有用于输入和输出的内置关键字，而是完全依赖于</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">类。</span></p>