.NET开发规范教程

BigTree 发表于 2013-8-15 11:40:00

<H4 style="TEXT-ALIGN: left; PADDING-BOTTOM: 0px; LINE-HEIGHT: 26px; TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-VARIANT: normal; FONT-STYLE: normal; TEXT-INDENT: 0px; MARGIN: 0px; PADDING-LEFT: 0px; LETTER-SPACING: normal; PADDING-RIGHT: 0px; FONT-FAMILY: Arial; WHITE-SPACE: normal; COLOR: rgb(51,51,51); FONT-SIZE: 14px; WORD-SPACING: 0px; PADDING-TOP: 0px; -webkit-text-stroke-width: 0px"><FONT size=2>在博客园上看到这篇很不错的.NET开发规范教程，转发与更多的朋友分享。原文地址：<SPAN style="FONT-SIZE: 12px">http://www.cnblogs.com/luanshixia/p/3258111.html</SPAN></FONT></H4>
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<H1 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t1></A><SPAN style="FONT-FAMILY: 'courier new', courier">1 概述</SPAN></H1>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t2></A><SPAN style="FONT-FAMILY: 'courier new', courier">1.1 意义</SPAN></H2>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">“.NET平台开发规范”包括两方面内容：代码规范、最佳实践。</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">（1）规范和优美的代码风格有助于思路清晰。</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">（2）规范和优美的代码有助于团队沟通交流。</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">（3）规范和优美的代码有助于学习近20年（后设计模式时代）现代面向对象思想发展的精华。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">.NET平台是继Java平台之后又一伟大的带集大成面向对象类库的虚拟机平台。.NET平台及其主力语言C#吸取了Java平台及Java语言的全部优点和精华（包括开发规范），并逐渐发展和独创出了鲜明的、先进的特色。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">众所周知，C#最初全盘照搬了Java。但时至今日，Java语言准备采用C#中的lambda语法。Java平台是个优秀的平台（类库、虚拟机），但Java语言却日益获得差评，于是JVM上的其他语言越来越多地取代了Java，如Groovy，Scala，JRuby等。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">.NET平台上的语言数量比Java平台有过之而无不及，但与之截然不同的是，C#始终在.NET中保持绝对优势地位。C#也许不是.NET上最优秀的语言，但已经足够优秀来进行生产。而Java语言却称不上足够优秀，因为有语言专门用来弥补它的不足，最典型的就是Scala。而Scala解决的问题，如函数式编程、并发编程，在C#中早有解决方案。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">毫不夸张地说，.NET是现代面向对象开发思想和实践的一个制高点，而C#则是编程语言发展趋势（声明性、动态性、并发性）的风向标。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">即使你是一名C++开发人员，你也能从中获益。</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">（4）规范是微软内部秘笈，优美是秘笈指导下的修炼。</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">这些规范和最佳实践多来源于微软负责CLR、BCL、C#/VB团队的成员。它们体现了.NET和C#设计人员的智慧结晶。例如，他们会告诉你哪些功能已经被哪些新功能取代而不建议使用，而新功能新方法总是以优雅的方式解决旧功能存在的问题，会给人启发，很值得回味，使用新功能收获的不仅是方便快捷，还有水平层次的提升。</SPAN></P>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t3></A><SPAN style="FONT-FAMILY: 'courier new', courier">1.2 后设计模式时代大事记</SPAN></H2>
<UL>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">Python/Ruby等动态面向对象语言的兴起</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">Java的诞生</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">.NET的诞生</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">Boost库的发展</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">函数式编程融入面向对象语言</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">其他门派面向对象语言JavaScript和Objective-C的繁荣</SPAN></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">新C++标准</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t4></A><SPAN style="FONT-FAMILY: 'courier new', courier">1.3 参考资料和延伸阅读</SPAN></H2>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">本教程主要综合以下资料中的观点和我公司开发实践写成：</SPAN></P>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">《C#编程风格》(The Elements of C# Style)</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">《.NET设计规范：约定、惯用法与模式（第二版）》(Framework Design Guidelines: Conventions, Idioms, and Patterns for Reusable .NET Libraries, 2nd Edition)</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">Effective C#: 50 Specific Ways to Improve Your C#, 1st and 2nd Edition</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">More Effective C#: 50 Specific Ways to Improve Your C#</SPAN></LI></UL>
<P><SPAN style="FONT-FAMILY: 'courier new', courier"><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt="" src="http://images.cnitblog.com/blog/146181/201308/14195557-77d1af3838264948a8483a044ab01528.png" width=787 height=250></SPAN></P>
<H1 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t5></A><SPAN style="FONT-FAMILY: 'courier new', courier">2 代码规范</SPAN></H1>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t6></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.1 空白</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用空行分隔逻辑块（函数、条件块、循环块等）</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">运算符空格（使用IDE自动设置）</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">命名空间导入，在不同公司或不同库的命名空间之间空一行。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t7></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.2 代码块</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">切分长语句为多行语句</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">左花括号也要单独成行，与右花括号在同一铅垂线上，与上一级花括号缩进一个制表位。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">始终使用语句块</SPAN></LI></UL>
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<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">正</PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">误</PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">if (a == null)</PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">{</PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"> return;</PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">}</PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">if (a == null) return;</PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用#region标记代码区域，便于折叠</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t8></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.3 命名</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用有意义的名称，如<SPAN class=Apple-converted-space> </SPAN></SPAN><SPAN style="FONT-FAMILY: 'courier new', courier">IsDepartmentReadyToOfferJob</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用完整单词，帕斯卡（Pascal）和骆驼（Camel）写法</SPAN></LI></UL>
<TABLE>
<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">正</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">误</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">NumberOfArgumentsIn</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">nargin</SPAN></PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">根据含义而非类型命名</SPAN></LI></UL>
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<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">正</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">误</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">ParcelName</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">strParcelName</SPAN></PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">不要用大小写区分名称</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">像普通词一样书写缩略词：XmlReader; System.Linq</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用复数形式书写集合名称</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">习惯性后缀（前缀）：</SPAN></LI></UL>
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<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">抽象基类</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">-Base</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">接口</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">I-</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">异常</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">-Exception</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">事件参数</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">-EventArgs</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">事件委托</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">-EventHandler</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier">特性</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier">-Attribute</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">泛型类型参数</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">T-</SPAN></PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">给实现一种设计模式的类加上模式名称，例如：工厂模式 - xxxFactory</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">泛型参数的命名：使用单个大写字母，如T, U等。需要时，写成TKey, TValue等</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">枚举的命名：普通枚举用单数名词，位域枚举用复数名词。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">接口的命名：使用I-加名词为声明服务的接口命名，使用I-加形容词为描述能力的接口命名。（例：IEnumerable和IEnumerator）</SPAN></LI></UL>
<P class=p0><SPAN style="BACKGROUND-COLOR: rgb(255,255,0); FONT-FAMILY: 'courier new', courier">[思考题1]</SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">从右边找出与左边项目相关的接口。</SPAN></P>
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<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">资源回收</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">a</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IFormattable</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">Convert.ToString()</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">b</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IEquatable</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">重载关系运算符</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">c</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IConvertible</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">if (textbox1.Text == "Hello")</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">d</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IClonable</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">Double.ToString()</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">e</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IDisposible</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">foreach循环</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">f</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IComparable</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">from p in q select p;</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">g</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IEnumerable</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=262><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">复制数组元素</SPAN></PRE></TD>
<TD vAlign=top width=36><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="FONT-FAMILY: 'courier new', courier"> </SPAN></PRE></TD>
<TD vAlign=top width=33><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">h</SPAN></PRE></TD>
<TD vAlign=top width=242><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">IQueryable</SPAN></PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用能体现布尔值特征的名称给布尔类型命名：IsXxx，HasXxx，CanXxx</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">方法的命名：用动[宾]结构、帕斯卡写法</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">变量和方法参数命名：用名词性结构、骆驼写法</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">成组的私有字段、公共属性和构造函数形参：_item, Item, item。见3.6节代码示例</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">习惯中允许使用的标准“一次性”变量名（只限这几个）：</SPAN></LI></UL>
<TABLE>
<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">i, j, k</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">循环变量（类型：System.Int32）</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">o</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">System.Object</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">s</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">System.String</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">e</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">事件实参（基类：System.EventArgs）</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">ex</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">异常（基类：System.Exception）</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">g</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">System.Drawing.Graphics</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">x, y, z</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">Lambda表达式的形参</SPAN></PRE></TD></TR></TBODY></TABLE>
<UL>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier"></SPAN><SPAN style="FONT-FAMILY: 'courier new', courier">命名空间的命名：公司名.产品名.技术/模块名。将相互依赖的类型放在同一命名空间下。不要污染框架命名空间（例如在System命名空间中添加类型）。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t9></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.4 注释</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用内建XML注释文档机制</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">内部注释：尽量少用，避免行末注释</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">不用C风格注释块/**/</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">在右花括号、else后面加注释辅助阅读</SPAN></LI></UL>
<TABLE>
<TBODY>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">1</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">2</SPAN></PRE></TD></TR>
<TR>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">if (a > 0)</SPAN></PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">{</SPAN></PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">}</SPAN></PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">else // a <= 0</SPAN></PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">{</SPAN></PRE><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">}</SPAN></PRE></TD>
<TD vAlign=top width=284><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap" class=p0 name="code"><SPAN style="FONT-FAMILY: 'courier new', courier">} // end of foreach</SPAN></PRE></TD></TR></TBODY></TABLE>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t10></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.5 字面量</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">避免使用数值字面量。使用常量表示一个值，使用枚举明确指示一个状态。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用枚举代替布尔值。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用标准形式书写浮点字面量。不必写f,d（一般只用double），但要对整数写上小数点。用科学计数法时注意小数点前只能有一位数，且不能是0。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">字符串字面量应该总是赋给变量使用。用string.Empty代替空串字面量。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t11></A><SPAN style="FONT-FAMILY: 'courier new', courier">2.6 其他</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">不要依赖运算符优先级。应当加上括号。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">单独声明每个变量，不要写int a, b。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">给switch语句加上default</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">for循环变量声明在循环作用域内部，foreach循环不要再声明循环变量。或用框架函数代替循环，它们的思想是一致的，见最佳实践。</SPAN></LI></UL>
<H1 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t12></A><SPAN style="FONT-FAMILY: 'courier new', courier">3 最佳实践</SPAN></H1>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t13></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.1 使用属性</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">属性是函数成员，没有存储空间。例：属性不能做ref/out参数。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">将成员字段全部私有，使用属性来获取，不需修改就不设set。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">属性应简单、低成本、无副作用、与调用顺序无关。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">属性返回集合应该总是只读。（用户代码可以清空集合、再添加元素，但不允许使对象引用改变）</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">属性返回其他引用类型也应该尽量考虑只读，用户代码依然可以修改成员。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">特殊的属性：索引器</SPAN></LI></UL>
<P class=p0><SPAN style="BACKGROUND-COLOR: rgb(255,255,0); FONT-FAMILY: 'courier new', courier">[思考题2]</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">string</SPAN> s = <SPAN style="COLOR: rgb(128,0,0)">"</SPAN><SPAN style="COLOR: rgb(128,0,0)">abcdeeg</SPAN><SPAN style="COLOR: rgb(128,0,0)">"</SPAN>;
s[<SPAN style="COLOR: rgb(128,0,128)">5</SPAN>] = <SPAN style="COLOR: rgb(128,0,0)">'</SPAN><SPAN style="COLOR: rgb(128,0,0)">f</SPAN><SPAN style="COLOR: rgb(128,0,0)">'</SPAN>;</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">以上代码在C++和C#中是否都合法？是否都有效？</SPAN></P>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t14></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.2 使用不可变值类型</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">为“值”语义使用struct。所谓值语义就是一种状态、属性，例如点（坐标）、颜色（分量）等，多具有短小数据量的特点。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">为struct的字段添加readonly修饰符，成为不可变（Immutable）类型。成员函数返回新实例，而不是修改this实例。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">值类型的成员字段只应使用基本CTS类型。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t15></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.3 转换</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用as和is运算符代替显式引用转换</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">基本类型的转换要使用System.Convert类</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">避免装箱和拆箱</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t16></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.4 字符串</SPAN></H2>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier"><SPAN style="BACKGROUND-COLOR: rgb(255,255,0)">[思考题3]</SPAN>检测一个字符串str是否以"abc"开头，有两种方法（不使用StartsWith）：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">str.SubString(<SPAN style="COLOR: rgb(128,0,128)">0</SPAN>, <SPAN style="COLOR: rgb(128,0,128)">3</SPAN>) == <SPAN style="COLOR: rgb(128,0,0)">"</SPAN><SPAN style="COLOR: rgb(128,0,0)">abc</SPAN><SPAN style="COLOR: rgb(128,0,0)">"</SPAN>;
str.IndexOf(<SPAN style="COLOR: rgb(128,0,0)">"</SPAN><SPAN style="COLOR: rgb(128,0,0)">abc</SPAN><SPAN style="COLOR: rgb(128,0,0)">"</SPAN>) == <SPAN style="COLOR: rgb(128,0,128)">0</SPAN>;</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">请问哪种方法好，为什么？</SPAN><SPAN style="FONT-FAMILY: 'courier new', courier"></SPAN></P>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">CLR中的字符串是不可变类型，字符串分配是一项昂贵的操作。因此我们有以下最佳做法：</SPAN></P>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用string.Empty代替空串字面量。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">用str.Length == 0或string.IsNullOrEmpty(str)检测空串，后者还兼容空引用。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">反复使用的字符串应当创建变量多次引用而不是每次都使用字面量（每出现一次字面量就要重新分配一次字符串）。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">不分大小写的比较应当用string.Compare(str1, str2, true)</SPAN><SPAN style="FONT-FAMILY: 'courier new', courier">而不是str1.ToUpper() == str2.ToUpper()。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">考虑使用string.Format()方法而不是字符串拼接来输出结果。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">大量拼接字符串要使用StringBuilder类。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t17></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.5 使用查询表达式代替循环</SPAN></H2>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">函数式编程为C#带来了高可读性的声明式语法。循环是一种命令式语法，在声明式语法中相应的是对集合的mapping操作。</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">以下代码生成前100个完全平方数：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">var</SPAN> squares = Enumerable.Range(<SPAN style="COLOR: rgb(128,0,128)">1</SPAN>, <SPAN style="COLOR: rgb(128,0,128)">100</SPAN>).Select(x => x * x);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">返回int数组：squares.ToArray();</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">返回List<int>集合：squares.ToList();</SPAN></P>
<P class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">以下代码对集合foos中每个元素执行DoSomething()成员方法：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">foos.ForEach(x => x.DoSomthing());</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">以下代码选出foos中大于100的元素：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">var</SPAN> q = foos.Where(x => x > <SPAN style="COLOR: rgb(128,0,128)">100</SPAN>);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">points中点按到原点距离排序：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">var</SPAN> q = points.OrderBy(x => x.DistTo(<SPAN style="COLOR: rgb(0,0,255)">new</SPAN> Point(<SPAN style="COLOR: rgb(128,0,128)">0</SPAN>, <SPAN style="COLOR: rgb(128,0,128)">0</SPAN>)));</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">foos中平方最小的数：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">double</SPAN> minSq = foos.Min(x => x * x);
<SPAN style="COLOR: rgb(0,0,255)">double</SPAN> min = foos.Distinct().Single(x => x * x == minSq);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<P><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">foos中的数是否有大于100的（是否都大于100）</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">foos.Any(x => x > <SPAN style="COLOR: rgb(128,0,128)">100</SPAN>);
foos.All(x => x > <SPAN style="COLOR: rgb(128,0,128)">100</SPAN>);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t18></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.6 返回多个值</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">在Matlab中可以用矩阵返回多个值，这就是元组(Tuple)的概念。当函数需要返回多个值时，应当使用元组而不是使用输出参数。.NET 4.0中提供了Tuple泛型类，位于System命名空间。在3.5以下版本可以考虑自己实现。</SPAN></LI></UL>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,0,255)">public</SPAN> <SPAN style="COLOR: rgb(0,0,255)">class</SPAN> Tuple<T1, T2>
{
<SPAN style="COLOR: rgb(0,0,255)">private</SPAN> T1 _item1;
<SPAN style="COLOR: rgb(0,0,255)">private</SPAN> T2 _item2;

<SPAN style="COLOR: rgb(0,0,255)">public</SPAN> T1 Item1 { <SPAN style="COLOR: rgb(0,0,255)">get</SPAN> { <SPAN style="COLOR: rgb(0,0,255)">return</SPAN> _item1; } }
<SPAN style="COLOR: rgb(0,0,255)">public</SPAN> T2 Item2 { <SPAN style="COLOR: rgb(0,0,255)">get</SPAN> { <SPAN style="COLOR: rgb(0,0,255)">return</SPAN> _item2; } }

<SPAN style="COLOR: rgb(0,0,255)">public</SPAN> Tuple(T1 item1, T2 item2)
{
   _item1 = item1;
   _item2 = item2;
}
}

<SPAN style="COLOR: rgb(0,0,255)">public</SPAN> <SPAN style="COLOR: rgb(0,0,255)">class</SPAN> TupleList<T1, T2> : List<Tuple<T1, T2>>
{
<SPAN style="COLOR: rgb(0,0,255)">public</SPAN> <SPAN style="COLOR: rgb(0,0,255)">void</SPAN> Add(T1 item1, T2 item2)
{
   <SPAN style="COLOR: rgb(0,0,255)">base</SPAN>.Add(<SPAN style="COLOR: rgb(0,0,255)">new</SPAN> Tuple<T1, T2>(item1, item2));
}
}</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<UL>
<LI><SPAN style="LINE-HEIGHT: 1.5; FONT-FAMILY: 'courier new', courier">在任何时候都应避免使用ref/out传递参数，尤其对引用类型（禁止引用的引用）。尝试改进你的设计。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t19></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.7 对象初始化</SPAN></H2>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">Button btn = <SPAN style="COLOR: rgb(0,0,255)">new</SPAN> Button { Text = <SPAN style="COLOR: rgb(128,0,0)">"</SPAN><SPAN style="COLOR: rgb(128,0,0)">Click me!</SPAN><SPAN style="COLOR: rgb(128,0,0)">"</SPAN>, BackColor = Color.FromArgb(<SPAN style="COLOR: rgb(128,0,128)">255</SPAN>, <SPAN style="COLOR: rgb(128,0,128)">255</SPAN>, <SPAN style="COLOR: rgb(128,0,128)">255</SPAN>) };
btn.Click += (sender, e) => MessageBox.Show(<SPAN style="COLOR: rgb(128,0,0)">"</SPAN><SPAN style="COLOR: rgb(128,0,0)">Hello!</SPAN><SPAN style="COLOR: rgb(128,0,0)">"</SPAN>);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t20></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.8 小函数</SPAN></H2>
<UL>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">将大函数分拆成小函数。这样做的好处有：</SPAN>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">合并重复代码，便于维护</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">增加函数层级，便于调试</SPAN></LI></UL></LI>
<LI class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">方法参数也不宜过多，否则也应考虑拆分。</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t21></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.9 using块和finally</SPAN></H2>
<P class=p0><SPAN style="FONT-FAMILY: 'courier new', courier">以下代码编译成相同IL：</SPAN></P>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap"><SPAN style="COLOR: rgb(0,128,0)">//</SPAN><SPAN style="COLOR: rgb(0,128,0)"> 1. Example Using clause:</SPAN>
<SPAN style="COLOR: rgb(0,0,255)">using</SPAN> (myConnection = <SPAN style="COLOR: rgb(0,0,255)">new</SPAN> SqlConnection(connString))
{
myConnection.Open();
}

<SPAN style="COLOR: rgb(0,128,0)">//</SPAN><SPAN style="COLOR: rgb(0,128,0)"> 2. Example Try / Catch block:</SPAN>
<SPAN style="COLOR: rgb(0,0,255)">try</SPAN>
{
myConnection = <SPAN style="COLOR: rgb(0,0,255)">new</SPAN> SqlConnection(connString);
myConnection.Open();
}
<SPAN style="COLOR: rgb(0,0,255)">finally</SPAN>
{
myConnection.Dispose();
}</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t22></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.10 使用泛型集合</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">不要使用非泛型的ArrayList，这会带来不必要的装箱和拆箱。使用System.Collections.Generic命名空间中的容器类型。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">代替数组的首选：List<T>。如被用户代码获取应该以只读属性形式提供。如果要真的使集合不可修改，可用ReadOnlyCollection<T>(System.Collections.ObjectModel)</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">集合做参数禁止ref/out传递（造成引用的引用）。值传递即可达到修改集合元素的目的。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">在多个函数间返回、传递的集合考虑用接口类型IEnumerable<T>和yield关键字。连续的LINQ语句考虑不急于调用ToList或ToArray。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">其他常用集合：Dictionary<TKey, TValue>; SortedSet<T>(.NET 4)</SPAN></LI></UL>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t23></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.11 充分利用BCL</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">BCL中提供了很多常用算法，并且还在不断扩充。例如，.NET 4增加了System.Numerics命名空间，目前包括BigIntegar和Complex类，而在bcl.codeplex.com上已经放出了BigRational类的候选版和源代码。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">尽可能只依赖BCL，减少第三方依赖。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">对字符串的操作都有简单的方法可以调用。用这些方法不仅能更方便省时、稳定高效，而且能使你的代码趋向于可读性强的声明式风格。</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">尽可能只用系统定义的委托，而不是自己定义委托类型。系统定义的委托包括：各种泛型参数数目的Func, Action; 一个Predicate<T>;各种EventHandler。以下是一个高阶函数的应用实例：</SPAN></LI></UL>
<DIV class=cnblogs_code>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV><PRE style="WORD-WRAP: break-word; WHITE-SPACE: pre-wrap">Func<Color, EventHandler> changeControlColor =
x => (sender, e) => (sender <SPAN style="COLOR: rgb(0,0,255)">as</SPAN> Control).BackColor = x;
button1.Click += changeControlColor(Colors.Red);</PRE>
<DIV class=cnblogs_code_toolbar><SPAN class=cnblogs_code_copy><IMG style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; MAX-WIDTH: 100%; BORDER-TOP: medium none; BORDER-RIGHT: medium none" alt=复制代码 src="http://common.cnblogs.com/images/copycode.gif"></SPAN></DIV></DIV>
<H2 style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"><A style="COLOR: rgb(51,102,153); TEXT-DECORATION: none" name=t24></A><SPAN style="FONT-FAMILY: 'courier new', courier">3.12 其他</SPAN></H2>
<UL>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">使用虚函数和多态而不是频繁使用引用转换</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">创建枚举0值表示未初始化、无效、未指定或默认</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">总是在派生类构造函数的初始化列表中列出所有基构造函数</SPAN></LI>
<LI class=p15><SPAN style="FONT-FAMILY: 'courier new', courier">总是重写ToString()方法</SPAN></LI></UL></DIV></DIV></DIV>

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