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📁 This ECMA Standard specifies the form and establishes the interpretation of programs written in the
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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="9.5.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="9.5.2.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="8.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="10.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="9.htm">9</a></span><span class="clause-title-previous"> Lexical structure</span></span><span class="clause-depth"><a href="9.4.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="9.5.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="9.5.htm">9.5</a></span><span class="clause-title-previous"> Pre-processing directives</span></span><span class="clause-depth"><a href="9.5.1.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="9.5.2.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">9.5.1</span><span class="clause-title"> Conditional compilation symbols</span></span><span class="locator">
     Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>The conditional compilation functionality provided by the <span class="symbol">#if</span>, <span class="symbol">#elif</span>, <span class="symbol">#else</span>, and <span class="symbol">#endif</span> directives is controlled through pre-processing expressions (<a href="9.5.2.htm">&#167;9.5.2</a>) and conditional compilation symbols.</span> <span class="grammar-production"><span class="name"><a name="conditional-symbol"></a>conditional-symbol</span> :: <span class="rhs">Any <span class="non-terminal"><a href="9.4.2.htm#identifier-or-keyword">identifier-or-keyword</a></span> except <span class="keyword">true</span> or <span class="keyword">false</span> </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>A conditional compilation symbol has two possible states: defined or undefined.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a>At the beginning of the lexical processing of a source file, a conditional compilation symbol is undefined unless it has been explicitly defined by an external mechanism (such as a command-line compiler option).</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P2S3"></a>When a <span class="symbol">#define</span> directive is processed, the conditional compilation symbol named in that directive becomes defined in that source file.</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P2S4"></a>The symbol remains defined until an <span class="symbol">#undef</span> directive for that same symbol is processed, or until the end of the source file is reached.</span> <span class="sentence"><span class="sentence-number">5</span> <a name="P2S5"></a>An implication of this is that <span class="symbol">#define</span> and <span class="symbol">#undef</span> directives in one source file have no effect on other source files in the same program.</span> </span><span class="locator">
     Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>The name space for conditional compilation symbols is distinct and separate from all other named entities in a C# program.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>Conditional compilation symbols can only be referenced in <span class="symbol">#define</span> and <span class="symbol">#undef</span> directives and in pre-processing expressions.</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>
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