feedc0de/boost_integer
1
0
Fork 0
forked from boostorg/integer
Code Pull Requests Activity

Initial HTML commit

Browse Source 
[SVN r7636]
This commit is contained in:
Beman Dawes
2000-07-27 14:04:40 +00:00
parent 5c0fd818f9
commit 1e3923c6e2
4 changed files with 376 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
integer.htm Normal file
View File

@ -0,0 +1,110 @@
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta name="GENERATOR" content="Microsoft FrontPage 4.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title>Integer Type Selection Templates</title>
</head>
<body bgcolor="#FFFFFF" text="#000000">
<h1><img src="../../c++boost.gif" alt="c++boost.gif (8819 bytes)" align="center" width="277" height="86">Integer
Type Selection Templates</h1>
<p>The <code><a href="../../boost/integer.hpp">&lt;boost/integer.hpp&gt;</a></code>
type selection templates allow integer types to be selected based on desired
characteristics such as number of bits or maximum value.&nbsp; This facility is
particularly useful for solving generic programming problems.</p>
<p>The templates <b>int_t&lt;&gt;</b> and <b>uint_t&lt;&gt;</b> supply typedefs <b>least</b>
and <b>fast</b>.&nbsp; The <b>least</b> type be the smallest type which holds at
least the number of bits (including sign) specified. The <b>fast</b> type will
be at least as large as the <b>least</b> type, but may possible be larger.&nbsp;
There is no guarantee that the <b>fast</b> type will actually be faster than
other possible types.</p>
<h2>Alternative</h2>
<p>If the number of bits required is known beforehand, it may be more
appropriate to use the types supplied in <code><a href="../../boost/cstdint.hpp">&lt;boost/cstdint.hpp&gt;</a></code>.</p>
<h2>Synopsis</h2>
<blockquote>
<pre>namespace boost
{
// fast integers from least integers
template&lt; typename LeastInt &gt; // Required: LeastInt is integral type, not bool
struct int_fast_t { typedef LeastInt fast; }; // implementations may specialize
// signed
template&lt; int Bits &gt; // bits (including sign) required, 0-32 valid
struct int_t
{
typedef <i>implementation-supplied</i> least;
typedef int_fast_t&lt;least&gt;::fast fast;
};
// unsigned
template&lt; int Bits &gt; // bits required, 0-32 valid
struct uint_t
{
typedef <i>implementation-supplied</i> least;
typedef int_fast_t&lt;least&gt;::fast fast;
};
} // namespace boost
</pre>
</blockquote>
<p>[Templates to select type based on maximum value are under development.]
</p>
<h2>Example</h2>
<blockquote>
<pre>#include &lt;boost/integer.hpp&gt;
using boost::int_t;
...
int_t&lt;24&gt;::least my_var; </pre>
</blockquote>
<h2>Demonstration Program</h2>
<p>The program <a href="integer_test.cpp">integer_test.cpp</a> is a not very
smart demonstration of the results from instantiating various <b>int_t&lt;&gt;</b>
and <b>uint_t&lt;&gt;</b> examples.</p>
<h2>Rationale</h2>
<p>The rationale for the design of the templates in this header includes:</p>
<ul>
<li>Avoid&nbsp; recursion because of concern about C++'s limited guaranteed
recursion depth (17).</li>
<li>Avoid macros on general principles.</li>
<li>Try to keep the design as simple as possible.</li>
</ul>
<h2>Credits</h2>
<p>The author of the Boost integer type choosing templates is <a href="../../people/beman_dawes.html">Beman
Dawes</a>.&nbsp; He thanks to <a href="../../people/valentin_bonnard.htm"> Valentin Bonnard</a> and
<a href="../../people/kevlin_henney.htm"> Kevlin Henney</a> for sharing their designs for similar templates.</p>
<hr>
<p>Revised&nbsp; August 31, 1999</p>
<p><EFBFBD> Copyright Beman Dawes 1999. Permission to copy, use, modify, sell
and distribute this document is granted provided this copyright notice appears in all
copies. This document is provided &quot;as is&quot; without express or implied warranty,
and with no claim as to its suitability for any purpose.</p>
<p></p>
<p>&nbsp;</p>
</body>
</html>