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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="11.1.2.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="11.1.4.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="10.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="12.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="11.htm">11</a></span><span class="clause-title-previous"> Types</span></span><span class="clause-depth"><a href="11.1.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="11.2.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="11.1.htm">11.1</a></span><span class="clause-title-previous"> Value types</span></span><span class="clause-depth"><a href="11.1.2.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="11.1.4.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">11.1.3</span><span class="clause-title"> Simple types</span></span><span class="locator">
Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>C# provides a set of predefined struct types called the simple types.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P1S2"></a>The simple types are identified through reserved words, but these reserved words are simply aliases for predefined struct types in the System namespace, as described in the table below.</span>
<table border="1">
<tr>
<th>Reserved word</th>
<th>Aliased type</th>
</tr>
<tr>
<td>sbyte</td>
<td>System.SByte</td>
</tr>
<tr>
<td>byte</td>
<td>System.Byte</td>
</tr>
<tr>
<td>short</td>
<td>System.Int16</td>
</tr>
<tr>
<td>ushort</td>
<td>System.UInt16</td>
</tr>
<tr>
<td>int</td>
<td>System.Int32</td>
</tr>
<tr>
<td>uint</td>
<td>System.UInt32</td>
</tr>
<tr>
<td>long</td>
<td>System.Int64</td>
</tr>
<tr>
<td>ulong</td>
<td>System.UInt64</td>
</tr>
<tr>
<td>char</td>
<td>System.Char</td>
</tr>
<tr>
<td>float</td>
<td>System.Single</td>
</tr>
<tr>
<td>double</td>
<td>System.Double</td>
</tr>
<tr>
<td>bool</td>
<td>System.Boolean</td>
</tr>
<tr>
<td>decimal</td>
<td>System.Decimal</td>
</tr>
</table>
</span><span class="locator">
Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>Because a simple type aliases a struct type, every simple type has members.</span> <span class="example">[Example: For example, <span class="keyword">int</span> has the members declared in System.Int32 and the members inherited from System.Object, and the following statements are permitted: <pre class="code-example">
int i = int.MaxValue; // System.Int32.MaxValue constant
string s = i.ToString(); // System.Int32.ToString() instance method
string t = 123.ToString(); // System.Int32.ToString() instance method
</pre>end example]</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a>The simple types differ from other struct types in that they permit certain additional operations: </span><ul><li><span class="sentence"><span class="sentence-number">3</span> <a name="P2S3"></a> Most simple types permit values to be created by writing literals (<a href="9.4.4.htm">§9.4.4</a>).</span> <span class="example">[Example: For example, 123 is a literal of type <span class="keyword">int</span> and 'a' is a literal of type <span class="keyword">char</span>. end example]</span> <span class="sentence"><span class="sentence-number">4</span> <a name="P2S4"></a>C# makes no provision for literals of struct types in general, and non-default values of other struct types are ultimately always created through instance constructors of those struct types.</span> </li><li><span class="sentence"><span class="sentence-number">5</span> <a name="P2S5"></a> When the operands of an expression are all simple type constants, the compiler evaluates the expression at compile-time.</span> <span class="sentence"><span class="sentence-number">6</span> <a name="P2S6"></a>Such an expression is known as a <span class="non-terminal"><a href="14.15.htm#constant-expression">constant-expression</a></span> (<a href="14.15.htm">§14.15</a>).</span> <span class="sentence"><span class="sentence-number">7</span> <a name="P2S7"></a>Expressions involving operators defined by other struct types are not considered to be constant expressions.</span> </li><li><span class="sentence"><span class="sentence-number">8</span> <a name="P2S8"></a> Through const declarations, it is possible to declare constants of the simple types (<a href="17.3.htm">§17.3</a>).</span> <span class="sentence"><span class="sentence-number">9</span> <a name="P2S9"></a>It is not possible to have constants of other struct types, but a similar effect is provided by static readonly fields.</span> </li><li><span class="sentence"><span class="sentence-number">10</span> <a name="P2S10"></a> Conversions involving simple types can participate in evaluation of conversion operators defined by other struct types, but a user-defined conversion operator can never participate in evaluation of another user-defined operator (<a href="13.4.2.htm">§13.4.2</a>).</span> </li></ul></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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