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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="17.9.3.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="17.10.1.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="17.9.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="17.11.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">17.10</span><span class="clause-title"> Instance constructors</span></span><span class="locator">
     Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>An instance constructor is a member that implements the actions required to initialize an instance of a class.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P1S2"></a>Instance constructors are declared using constructor-declarations: <span class="grammar-production"><span class="name"><a name="constructor-declaration"></a>constructor-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="17.10.htm#constructor-modifiers">constructor-modifiers</a></span><sub>opt</sub> <span class="non-terminal"><a href="17.10.htm#constructor-declarator">constructor-declarator</a></span> <span class="non-terminal"><a href="17.10.htm#constructor-body">constructor-body</a></span> </span></span><span class="grammar-production"><span class="name"><a name="constructor-modifiers"></a>constructor-modifiers</span> : <span class="rhs"><span class="non-terminal"><a href="17.10.htm#constructor-modifier">constructor-modifier</a></span> </span><span class="rhs"><span class="non-terminal"><a href="17.10.htm#constructor-modifiers">constructor-modifiers</a></span> <span class="non-terminal"><a href="17.10.htm#constructor-modifier">constructor-modifier</a></span> </span></span><span class="grammar-production"><span class="name"><a name="constructor-modifier"></a>constructor-modifier</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">extern</span> </span></span><span class="grammar-production"><span class="name"><a name="constructor-declarator"></a>constructor-declarator</span> : <span class="rhs"><span class="non-terminal"><a href="9.4.2.htm#identifier">identifier</a></span> <span class="terminal">(</span> <span class="non-terminal"><a href="17.5.1.htm#formal-parameter-list">formal-parameter-list</a></span><sub>opt</sub> <span class="terminal">)</span> <span class="non-terminal"><a href="17.10.htm#constructor-initializer">constructor-initializer</a></span><sub>opt</sub> </span></span><span class="grammar-production"><span class="name"><a name="constructor-initializer"></a>constructor-initializer</span> : <span class="rhs"><span class="terminal">:</span> <span class="keyword">base</span> <span class="terminal">(</span> <span class="non-terminal"><a href="14.4.1.htm#argument-list">argument-list</a></span><sub>opt</sub> <span class="terminal">)</span> </span><span class="rhs"><span class="terminal">:</span> <span class="keyword">this</span> <span class="terminal">(</span> <span class="non-terminal"><a href="14.4.1.htm#argument-list">argument-list</a></span><sub>opt</sub> <span class="terminal">)</span> </span></span><span class="grammar-production"><span class="name"><a name="constructor-body"></a>constructor-body</span> : <span class="rhs"><span class="non-terminal"><a href="15.2.htm#block">block</a></span> </span><span class="rhs"><span class="terminal">;</span> </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 <span class="non-terminal"><a href="17.10.htm#constructor-declaration">constructor-declaration</a></span> may include a set of attributes (<a href="24.htm">&#167;24</a>), a valid combination of the four access modifiers (<a href="17.2.3.htm">&#167;17.2.3</a>), and an extern (<a href="17.5.7.htm">&#167;17.5.7</a>) modifier.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a>A constructor declaration is not permitted to include the same modifier multiple times.</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 identifier of a <span class="non-terminal"><a href="17.10.htm#constructor-declarator">constructor-declarator</a></span> must name the class in which the instance constructor is declared.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>If any other name is specified, a compile-time error occurs.</span> </span><span class="locator">
     Paragraph 4</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P4S1"></a>The optional <span class="non-terminal"><a href="17.5.1.htm#formal-parameter-list">formal-parameter-list</a></span> of an instance constructor is subject to the same rules as the  <span class="non-terminal"><a href="17.5.1.htm#formal-parameter-list">formal-parameter-list</a></span> of a method (<a href="17.5.htm">&#167;17.5</a>).</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P4S2"></a>The formal parameter list defines the signature (<a href="10.6.htm">&#167;10.6</a>) of an instance constructor and governs the process whereby overload resolution (<a href="14.4.2.htm">&#167;14.4.2</a>) selects a particular instance constructor in an invocation.</span> </span><span class="locator">
     Paragraph 5</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P5S1"></a>Each of the types referenced in the <span class="non-terminal"><a href="17.5.1.htm#formal-parameter-list">formal-parameter-list</a></span> of an instance constructor must be at least as accessible as the constructor itself (<a href="10.5.4.htm">&#167;10.5.4</a>).</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 optional <span class="non-terminal"><a href="17.10.htm#constructor-initializer">constructor-initializer</a></span> specifies another instance constructor to invoke before executing the statements given in the <span class="non-terminal"><a href="17.10.htm#constructor-body">constructor-body</a></span> of this instance constructor.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P6S2"></a>This is described further in <a href="17.10.1.htm">&#167;17.10.1</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>When a constructor declaration includes an extern modifier, the constructor is said to be an external constructor.</span> </span><span class="locator">
     Paragraph 8</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P8S1"></a>Because an external constructor declaration provides no actual implementation, its <span class="non-terminal"><a href="17.10.htm#constructor-body">constructor-body</a></span> consists of a semicolon.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P8S2"></a>For all other constructors, the <span class="non-terminal"><a href="17.10.htm#constructor-body">constructor-body</a></span> consists of a block, which specifies the statements to initialize a new instance of the class.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P8S3"></a>This corresponds exactly to the block of an instance method with a <span class="keyword">void</span> return type (<a href="17.5.8.htm">&#167;17.5.8</a>).</span> </span><span class="locator">
     Paragraph 9</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P9S1"></a>Instance constructors are not inherited.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P9S2"></a>Thus, a class has no instance constructors other than those actually declared in the class.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P9S3"></a>If a class contains no instance constructor declarations, a default instance constructor is automatically provided (<a href="17.10.4.htm">&#167;17.10.4</a>).</span> </span><span class="locator">
     Paragraph 10</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P10S1"></a>Instance constructors are invoked by <span class="non-terminal"><a href="14.5.10.1.htm#object-creation-expression">object-creation-expression</a></span>s (<a href="14.5.10.1.htm">&#167;14.5.10.1</a>) and through  <span class="non-terminal"><a href="17.10.htm#constructor-initializer">constructor-initializer</a></span>s.</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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