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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="14.5.6.1.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="14.5.7.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="13.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="15.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="14.htm">14</a></span><span class="clause-title-previous"> Expressions</span></span><span class="clause-depth"><a href="14.4.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="14.6.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="14.5.htm">14.5</a></span><span class="clause-title-previous"> Primary expressions</span></span><span class="clause-depth"><a href="14.5.5.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="14.5.7.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="14.5.6.htm">14.5.6</a></span><span class="clause-title-previous"> Element access</span></span><span class="clause-depth"><a href="14.5.6.1.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="14.5.6.2.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">14.5.6.2</span><span class="clause-title"> Indexer access</span></span><span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>For an indexer access, the <span class="non-terminal"><a href="14.5.htm#primary-no-array-creation-expression">primary-no-array-creation-expression</a></span> of the element-accessmust be a variable or value of a class, struct, or interface type, and this type must implement one or more indexers that are applicable with respect to the <span class="non-terminal"><a href="14.5.6.htm#expression-list">expression-list</a></span> of the <span class="non-terminal"><a href="14.5.6.htm#element-access">element-access</a></span>.</span> </span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>The compile-time processing of an indexer access of the form P[A], where P is a <span class="non-terminal"><a href="14.5.htm#primary-no-array-creation-expression">primary-no-array-creation-expression</a></span> of a class, struct, or interface type T, and A is an <span class="non-terminal"><a href="14.5.6.htm#expression-list">expression-list</a></span>, consists of the following steps: </span><ul><li><span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a> The set of indexers provided by T is constructed.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P2S3"></a>The set consists of all indexers declared in T or a base type of T that are not override declarations and are accessible in the current context (<a href="10.5.htm">§10.5</a>).</span> </li><li><span class="sentence"><span class="sentence-number">4</span> <a name="P2S4"></a> The set is reduced to those indexers that are applicable and not hidden by other indexers.</span> <span class="sentence"><span class="sentence-number">5</span> <a name="P2S5"></a>The following rules are applied to each indexer S.I in the set, where S is the type in which the indexer I is declared: </span></li><ul><li><span class="sentence"><span class="sentence-number">6</span> <a name="P2S6"></a> If I is not applicable with respect to A (<a href="14.4.2.1.htm">§14.4.2.1</a>), then I is removed from the set.</span> </li><li><span class="sentence"><span class="sentence-number">7</span> <a name="P2S7"></a> If I is applicable with respect to A (<a href="14.4.2.1.htm">§14.4.2.1</a>), then all indexers declared in a base type of S are removed from the set.</span> </li></ul><li><span class="sentence"><span class="sentence-number">8</span> <a name="P2S8"></a> If the resulting set of candidate indexers is empty, then no applicable indexers exist, and a compile-time error occurs.</span> <span class="sentence"><span class="sentence-number">9</span> <a name="P2S9"></a>If the candidate indexers are not all declared in the same type, the indexer access is ambiguous, and a compile-time error occurs (this latter situation can only occur for an indexer access on an instance of an interface that has multiple direct base interfaces).</span> </li><li><span class="sentence"><span class="sentence-number">10</span> <a name="P2S10"></a> The best indexer of the set of candidate indexers is identified using the overload resolution rules of <a href="14.4.2.htm">§14.4.2</a>.</span> <span class="sentence"><span class="sentence-number">11</span> <a name="P2S11"></a>If a single best indexer cannot be identified, the indexer access is ambiguous, and a compile-time error occurs.</span> </li><li><span class="sentence"><span class="sentence-number">12</span> <a name="P2S12"></a> The index expressions of the <span class="non-terminal"><a href="14.5.6.htm#expression-list">expression-list</a></span> are evaluated in order, from left to right.</span> <span class="sentence"><span class="sentence-number">13</span> <a name="P2S13"></a>The result of processing the indexer access is an expression classified as an indexer access.</span> <span class="sentence"><span class="sentence-number">14</span> <a name="P2S14"></a>The indexer access expression references the indexer determined in the step above, and has an associated instance expression of P and an associated argument list of A.</span> </li></ul></span><span class="locator">
Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>Depending on the context in which it is used, an indexer access causes invocation of either the get-accessor or the set-accessor of the indexer.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>If the indexer access is the target of an assignment, the set-accessor is invoked to assign a new value (<a href="14.13.1.htm">§14.13.1</a>).</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P3S3"></a>In all other cases, the get-accessor is invoked to obtain the current value (<a href="14.1.1.htm">§14.1.1</a>).</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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