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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>Hyperlinked ECMA C# Language Specification</title><meta name="author" content="Jon Jagger" /><link rel="stylesheet" href="ecma334.css"></link></head><body><div align="right"><em><a href="http://www.jaggersoft.com">Jon Jagger</a></em></div><div align="right"><a href="mailto:jon@jaggersoft.com">jon@jaggersoft.com</a></div><form method="get" action="http://search.atomz.com/search/"><input size="30" name="sp-q"></input><input type="submit" value="Search C# Spec"></input><input type="hidden" name="sp-a" value="sp10024177"></input><input type="hidden" name="sp-f" value="ISO-8859-1"></input></form><a href="toc.htm">Table of Contents</a> <a href="1.htm">1</a> <a href="2.htm">2</a> <a href="3.htm">3</a> <a href="4.htm">4</a> <a href="5.htm">5</a> <a href="6.htm">6</a> <a href="7.htm">7</a> <a href="8.htm">8</a> <a href="9.htm">9</a> <a href="10.htm">10</a> <a href="11.htm">11</a> <a href="12.htm">12</a> <a href="13.htm">13</a> <a href="14.htm">14</a> <a href="15.htm">15</a> <a href="16.htm">16</a> <a href="17.htm">17</a> <a href="18.htm">18</a> <a href="19.htm">19</a> <a href="20.htm">20</a> <a href="21.htm">21</a> <a href="22.htm">22</a> <a href="23.htm">23</a> <a href="24.htm">24</a> <a href="25.htm">25</a> <a href="notes.htm">Notes</a> <a href="HyperlinkedCSharpECMA.zip">Download</a><span class="ruler"></span><span class="heading">ECMA-334 C# Language Specification</span><span class="navigate"><a href="17.5.9.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="17.6.1.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="16.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="18.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="17.htm">17</a></span><span class="clause-title-previous"> Classes</span></span><span class="clause-depth"><a href="17.5.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="17.7.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">17.6</span><span class="clause-title"> Properties</span></span><span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>A property is a member that provides access to an attribute of an object or a class.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P1S2"></a>Examples of properties include the length of a string, the size of a font, the caption of a window, the name of a customer, and so on.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P1S3"></a>Properties are a natural extension of fields-both are named members with associated types, and the syntax for accessing fields and properties is the same.</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P1S4"></a>However, unlike fields, properties do not denote storage locations.</span> <span class="sentence"><span class="sentence-number">5</span> <a name="P1S5"></a>Instead, properties have accessors that specify the statements to be executed when their values are read or written.</span> <span class="sentence"><span class="sentence-number">6</span> <a name="P1S6"></a>Properties thus provide a mechanism for associating actions with the reading and writing of an object's attributes; furthermore, they permit such attributes to be computed.</span> </span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>Properties are declared using property-declarations: <span class="grammar-production"><span class="name"><a name="property-declaration"></a>property-declaration</span> : <span class="rhs"><span class="non-terminal"><a href="24.2.htm#attributes">attributes</a></span><sub>opt</sub> <span class="non-terminal"><a href="17.6.htm#property-modifiers">property-modifiers</a></span><sub>opt</sub> <span class="non-terminal"><a href="11.htm#type">type</a></span> <span class="non-terminal"><a href="17.6.htm#member-name">member-name</a></span> <span class="terminal">{</span> <span class="non-terminal"><a href="17.6.2.htm#accessor-declarations">accessor-declarations</a></span> <span class="terminal">}</span> </span></span><span class="grammar-production"><span class="name"><a name="property-modifiers"></a>property-modifiers</span> : <span class="rhs"><span class="non-terminal"><a href="17.6.htm#property-modifier">property-modifier</a></span> </span><span class="rhs"><span class="non-terminal"><a href="17.6.htm#property-modifiers">property-modifiers</a></span> <span class="non-terminal"><a href="17.6.htm#property-modifier">property-modifier</a></span> </span></span><span class="grammar-production"><span class="name"><a name="property-modifier"></a>property-modifier</span> : <span class="rhs"><span class="keyword">new</span> </span><span class="rhs"><span class="keyword">public</span> </span><span class="rhs"><span class="keyword">protected</span> </span><span class="rhs"><span class="keyword">internal</span> </span><span class="rhs"><span class="keyword">private</span> </span><span class="rhs"><span class="keyword">static</span> </span><span class="rhs"><span class="keyword">virtual</span> </span><span class="rhs"><span class="keyword">sealed</span> </span><span class="rhs"><span class="keyword">override</span> </span><span class="rhs"><span class="keyword">abstract</span> </span><span class="rhs"><span class="keyword">extern</span> </span></span><span class="grammar-production"><span class="name"><a name="member-name"></a>member-name</span> : <span class="rhs"><span class="non-terminal"><a href="9.4.2.htm#identifier">identifier</a></span> </span><span class="rhs"><span class="non-terminal"><a href="11.2.htm#interface-type">interface-type</a></span> <span class="terminal">.</span> <span class="non-terminal"><a href="9.4.2.htm#identifier">identifier</a></span> </span></span></span></span><span class="locator">
Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>A <span class="non-terminal"><a href="17.6.htm#property-declaration">property-declaration</a></span> may include a set of attributes (<a href="24.htm">§24</a>) and a valid combination of the four access modifiers (<a href="17.2.3.htm">§17.2.3</a>), the new (<a href="17.2.2.htm">§17.2.2</a>), static (<a href="17.6.1.htm">§17.6.1</a>), virtual (<a href="17.5.3.htm">§17.5.3</a>, <a href="17.6.3.htm">§17.6.3</a>), override (<a href="17.5.4.htm">§17.5.4</a>, <a href="17.6.3.htm">§17.6.3</a>), sealed (<a href="17.5.5.htm">§17.5.5</a>), abstract (<a href="17.5.6.htm">§17.5.6</a>, <a href="17.6.3.htm">§17.6.3</a>), and extern modifiers.</span> </span><span class="locator">
Paragraph 4</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P4S1"></a>Property declarations are subject to the same rules as method declarations (<a href="17.5.htm">§17.5</a>) with regard to valid combinations of modifiers.</span> </span><span class="locator">
Paragraph 5</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P5S1"></a>The type of a property declaration specifies the type of the property introduced by the declaration, and the <span class="non-terminal"><a href="17.6.htm#member-name">member-name</a></span> specifies the name of the property.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P5S2"></a>Unless the property is an explicit interface member implementation, the <span class="non-terminal"><a href="17.6.htm#member-name">member-name</a></span> is simply an identifier.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P5S3"></a>For an explicit interface member implementation (<a href="20.4.1.htm">§20.4.1</a>), the <span class="non-terminal"><a href="17.6.htm#member-name">member-name</a></span> consists of an <span class="non-terminal"><a href="11.2.htm#interface-type">interface-type</a></span> followed by a "." and an identifier.</span> </span><span class="locator">
Paragraph 6</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P6S1"></a>The type of a property must be at least as accessible as the property itself (<a href="10.5.4.htm">§10.5.4</a>).</span> </span><span class="locator">
Paragraph 7</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P7S1"></a>The <span class="non-terminal"><a href="17.6.2.htm#accessor-declarations">accessor-declarations</a></span>, which must be enclosed in "{" and "}" tokens, declare the accessors (<a href="17.6.2.htm">§17.6.2</a>) of the property.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P7S2"></a>The accessors specify the executable statements associated with reading and writing the property.</span> </span><span class="locator">
Paragraph 8</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P8S1"></a>Even though the syntax for accessing a property is the same as that for a field, a property is not classified as a variable.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P8S2"></a>Thus, it is not possible to pass a property as a ref or out argument.</span> </span><span class="locator">
Paragraph 9</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P9S1"></a>When a property declaration includes an extern modifier, the property is said to be an external property.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P9S2"></a>Because an external property declaration provides no actual implementation, each of its <span class="non-terminal"><a href="17.6.2.htm#accessor-declarations">accessor-declarations</a></span> consists of a semicolon.</span> </span><span class="ruler"></span><table><tr><td><table align="left" bgcolor="navy"><tr bgcolor="navy"><td><font face="Arial,sans-serif" size="6" color="yellow"><strong>{ JSL }</strong></font></td></tr></table></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Jagger Software Ltd</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>Company # 4070126</strong></font></td></tr><tr><td><font face="Arial,sans-serif" size="2" color="navy"><strong>VAT # 762 5213 42</strong></font></td></tr></table><img src="valid-html401.png" align="left" height="31" width="88" alt="Valid HTML 4.01" /><img src="vcss.gif" align="left" height="31" width="88" alt="Valid CSS" /></body></html>⌨️ 快捷键说明
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