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来自「This ECMA Standard specifies the form an」· HTM 代码 · 共 38 行

<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:[e-mail]">[e-mail]</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="25.5.5.htm"><img src="previous.gif" alt="previous" border="0" /></a><a href="25.5.7.htm"><img src="next.gif" alt="next" border="0" /></a></span><span class="clause-depth"><a href="24.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="25.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="25.htm">25</a></span><span class="clause-title-previous"> Unsafe code</span></span><span class="clause-depth"><a href="25.4.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="25.6.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number-link"><a href="25.5.htm">25.5</a></span><span class="clause-title-previous"> Pointers in expressions</span></span><span class="clause-depth"><a href="25.5.5.htm"><img src="previous.gif" alt="previous at this level" border="0" /></a><a href="25.5.7.htm"><img src="next.gif" alt="next at this level" border="0" /></a> <span class="clause-number">25.5.6</span><span class="clause-title"> Pointer arithmetic</span></span><span class="locator">
     Paragraph 1</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P1S1"></a>In an unsafe context, the + operator (<a href="14.7.4.htm">&#167;14.7.4</a>) and  -operator (<a href="14.7.5.htm">&#167;14.7.5</a>) can be applied to values of all pointer types except void*.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P1S2"></a>Thus, for every pointer type T*, the following operators are implicitly defined: <pre class="code-example">
T* operator +(T* x, int y);  
T* operator +(T* x, uint y);  
T* operator +(T* x, long y);  
T* operator +(T* x, ulong y);  
T* operator +(int x, T* y);  
T* operator +(uint x, T* y);  
T* operator +(long x, T* y);  
T* operator +(ulong x, T* y);  
T* operator -(T* x, int y);  
T* operator -(T* x, uint y);  
T* operator -(T* x, long y);  
T* operator -(T* x, ulong y);  
long operator -(T* x, T* y);  
</pre></span></span><span class="locator">
     Paragraph 2</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P2S1"></a>Given an expression P of a pointer type T* and an expression N of type <span class="keyword">int</span>, <span class="keyword">uint</span>, <span class="keyword">long</span>, or <span class="keyword">ulong</span>, the expressions P + N and N + P compute the pointer value of type T* that results from adding N * sizeof(T) to the address given by P.</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P2S2"></a>Likewise, the expression P  -N computes the pointer value of type T* that results from subtracting N * sizeof(T) from the address given by P.</span> </span><span class="locator">
     Paragraph 3</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P3S1"></a>Given two expressions, P and Q, of a pointer type T*, the expression P  -Q computes the difference between the addresses given by P and Q and then divides that difference by sizeof(T).</span> <span class="sentence"><span class="sentence-number">2</span> <a name="P3S2"></a>The type of the result is always <span class="keyword">long</span>.</span> <span class="sentence"><span class="sentence-number">3</span> <a name="P3S3"></a>In effect, P  -Q is computed as ((<span class="keyword">long</span>)(P)  -(<span class="keyword">long</span>)(Q)) / sizeof(T).</span> </span><span class="paragraph"><span class="example">[Example: For example: <pre class="code-example">
using System;  
class Test  
{  
   static void Main() {  
      unsafe {  
         int* values = stackalloc int[20];  
         
         int* p = &amp;values[1];  
         int* q = &amp;values[15];  
         
         Console.WriteLine("p - q = {0}", p - q);  
         Console.WriteLine("q - p = {0}", q - p);  
      }  
   }  
}  
</pre>which produces the output: <pre class="code-example">
p - q = -14  
q - p = 14  
</pre>end example]</span> </span><span class="locator">
     Paragraph 4</span><span class="paragraph"><span class="sentence"><span class="sentence-number">1</span> <a name="P4S1"></a>If a pointer arithmetic operation overflows the domain of the pointer type, the result is truncated in an implementation-defined fashion, but no exceptions are produced.</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>