📄 00383.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN">
<html>
<head>
<title>3.12 类</title>
<meta http-equiv="Content-Type" content="text/html; charset=GB2312" />
<meta name="generator" content="Doc-O-Matic" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<link rel="STYLESHEET" href="default.css" type="text/css" />
<script type="text/javascript" src="scripts.js"></script>
</head>
<body class="Element700" onload="onBodyLoadEx('systemverilog31a.html', 'topic', '00383.html');" onmousedown="onBodyMouseDown();">
<!-- Begin Popups -->
<div class="Element801" id="popup00051">
<div class="Element800">
<div class="Element14">
链接</div>
<div class="Element11">
<div class="Element10">
<a href="00863.html" target="topic">第三章 数据类型</a></div>
</div>
</div>
</div>
<!-- End Popups -->
<!-- Begin Page Header -->
<div class="Element710" id="areafixed">
<div class="Element92">
<table width="100%" cellspacing="0" cellpadding="0">
<tr><td width="33%">
<div class="Element1">
<a href="#" onmousedown="showPopup(this, 'popup00051');"><img src="seealsolink.png" border="0" alt="" title=""></a> SystemVerilog 3.1a语言参考手册</div>
</td><td width="34%">
<div class="Element2">
</div>
</td><td width="33%">
<div class="Element90">
<a href="00382.html" target="topic"><img src="btn_prev_lightblue.gif" border="0" alt="Previous" title="Previous" onmouseover="switchImage(this, 'btn_prev_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_prev_lightblue.gif');"></a><a href="00863.html" target="topic"><img src="btn_up_lightblue.gif" border="0" alt="Up" title="Up" onmouseover="switchImage(this, 'btn_up_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_up_lightblue.gif');"></a><a href="00384.html" target="topic"><img src="btn_next_lightblue.gif" border="0" alt="Next" title="Next" onmouseover="switchImage(this, 'btn_next_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_next_lightblue.gif');"></a></div>
</td></tr></table><div class="Element5">
3.12 类</div>
</div>
</div>
<!-- End Page Header -->
<!-- Begin Client Area -->
<div class="Element720" id="areascroll">
<div class="Element721">
<!-- Begin Page Content -->
<div class="Element58">
<a name="描述"></a><div class="Element11">
<div class="Element10">
<p class="Element10">
类是数据以及一组对数据进行操作的子程序的集合。类中的数据被称为类属性，它的子程序被称为方法。类属性和方法一起定义了一个类实例或对象的内容和能力。 </p><div class="Element170">
<a href="#" onclick="CopyElementToClipboard('code00083');">Copy Code</a></div>
<div class="Element13"><div class="Element12" id="code00083"><pre class="Element12">class_declaration ::= <span style="color: #008000">// 引用自附录A.1.3</span>
[<strong><span style="color: #FF0000">virtual</span></strong>] <strong><span style="color: #FF0000">class</span></strong> [lifetime] class_identifier [parameter_port_list]
[<strong><span style="color: #FF0000">extends</span></strong> class_type [<strong><span style="color: #FF0000">(</span></strong>list_of_arguments<strong><span style="color: #FF0000">)</span></strong>]]<strong><span style="color: #FF0000">;</span></strong>
{class_item}
<strong><span style="color: #FF0000">endclass</span></strong> [<span style="color: #FF0000">:</span> class_identifier]</pre></div></div>
<p class="Element10" style="text-align: center">
<strong>语法 3-5 — 类（摘录自附录A）</strong></p><p class="Element10">
</p>
<p class="Element10">
面向对象的类扩展允许动态地产生和销毁对象。类实例或者说对象能够通过对象句柄进行传递，这就为语言加入了一个安全指针的能力。一个对象可以声明成具有<span style="color: #0000FF">input</span>、<span style="color: #0000FF">output</span>、<span style="color: #0000FF">inout</span>或<span style="color: #0000FF">ref</span>方向的自变量。在每一种情况中，拷贝的自变量是对象句柄而不是对象的内容。 </p>
<p class="Element10">
</p>
<p class="Element10">
一个类使用<span style="color: #0000FF">class</span>...<span style="color: #0000FF">endclass</span>关键字进行声明。例如： </p><div class="Element170">
<a href="#" onclick="CopyElementToClipboard('code00084');">Copy Code</a></div>
<div class="Element13"><div class="Element12" id="code00084"><pre class="Element12"><span style="color: #0000FF">class</span> Packet<span style="color: #800080">;</span>
<span style="color: #0000FF">int</span> address<span style="color: #800080">;</span> <span style="color: #008000">// address、data和crc属性</span>
<span style="color: #0000FF">bit</span> <span style="color: #800080">[</span><span style="color: #FF0000">63</span><span style="color: #800080">:</span><span style="color: #FF0000">0</span><span style="color: #800080">]</span> data<span style="color: #800080">;</span>
<span style="color: #0000FF">shortint</span> crc<span style="color: #800080">;</span>
Packet next<span style="color: #800080">;</span> <span style="color: #008000">// 另一个Packet的句柄</span>
<span style="color: #0000FF">function</span> new<span style="color: #800080">();</span> <span style="color: #008000">// send和new方法</span>
<span style="color: #0000FF">function</span> <span style="color: #0000FF">bit</span> send<span style="color: #800080">();</span>
<span style="color: #0000FF">endclass</span> <span style="color: #800080">:</span> Packet</pre></div></div>
<p class="Element10">
任何数据类型都可以声明成一个类成员。类将会在<a href="00872.html" target="topic">第十一章</a>进行更详细的讨论。</p></div>
</div>
<a name="Group"></a><div class="Element14">
<a onclick="toggleVisibilityStored('Group');" class="a_Element14"><img src="sectionminus.png" border="0" alt="" title="" id="imgGroup">Group</a></div>
<div id="divGroup">
<div class="Element11">
<div class="Element10">
<p class="Element10">
<a href="00863.html" target="topic">第三章 数据类型</a></p></div>
</div>
</div>
<a name="Links"></a><div class="Element14">
<a onclick="toggleVisibilityStored('链接');" class="a_Element14"><img src="sectionminus.png" border="0" alt="" title="" id="img链接">链接</a></div>
<div id="div链接">
<div class="Element11">
<div class="Element10">
<a href="00863.html" target="topic">第三章 数据类型</a></div>
</div>
</div>
</div>
<!-- End Page Content -->
<!-- Begin Page Footer -->
<hr width="98%" align="center" size="1" color="#CCCCCC" />
<table align="center" cellpadding="0" cellspacing="0" border="0">
<tbody>
<tr height="10">
<td></td>
</tr>
<tr align="center">
<td>
<script type="text/javascript"><!--
google_ad_client = "pub-5266859600380184";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text_image";
google_ad_channel ="";
google_page_url = document.location;
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
</tr>
<tr height="15">
<td></td>
</tr>
<tr align="center">
<td>
<font size=2>除非特别声明，原文版权归作者所有，如有转摘请注明原作者以及译者（<a href="http://www.fpgatech.net/" target="_blank">FPGA技术网</a>）信息。<br />
如果您对本主题有何建议或意见，请登陆<a href="http://www.fpgatech.net/forum/forumdisplay.php?fid=18" target="_blank">FPGA开发者家园</a>提交，您的参与是我们前进的动力。</font>
<script language="javascript" type="text/javascript" src="http://js.users.51.la/195685.js"></script>
<noscript><a href="http://www.51.la/?195685" target="_blank"><img alt="我要啦免费统计" src="http://img.users.51.la/195685.asp" style="border:none" /></a></noscript>
</td>
</tr>
</tbody>
</table>
<!-- End Page Footer -->
</div>
</div>
<!-- End Client Area -->
</body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -