1<html lang="en"> 2<head> 3<title>Binary constants - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions"> 9<link rel="prev" href="Thread_002dLocal.html#Thread_002dLocal" title="Thread-Local"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<!-- 12Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 131998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 142010 Free Software Foundation, Inc. 15 16Permission is granted to copy, distribute and/or modify this document 17under the terms of the GNU Free Documentation License, Version 1.3 or 18any later version published by the Free Software Foundation; with the 19Invariant Sections being ``Funding Free Software'', the Front-Cover 20Texts being (a) (see below), and with the Back-Cover Texts being (b) 21(see below). A copy of the license is included in the section entitled 22``GNU Free Documentation License''. 23 24(a) The FSF's Front-Cover Text is: 25 26 A GNU Manual 27 28(b) The FSF's Back-Cover Text is: 29 30 You have freedom to copy and modify this GNU Manual, like GNU 31 software. Copies published by the Free Software Foundation raise 32 funds for GNU development.--> 33<meta http-equiv="Content-Style-Type" content="text/css"> 34<style type="text/css"><!-- 35 pre.display { font-family:inherit } 36 pre.format { font-family:inherit } 37 pre.smalldisplay { font-family:inherit; font-size:smaller } 38 pre.smallformat { font-family:inherit; font-size:smaller } 39 pre.smallexample { font-size:smaller } 40 pre.smalllisp { font-size:smaller } 41 span.sc { font-variant:small-caps } 42 span.roman { font-family:serif; font-weight:normal; } 43 span.sansserif { font-family:sans-serif; font-weight:normal; } 44--></style> 45<link rel="stylesheet" type="text/css" href="../cs.css"> 46</head> 47<body> 48<div class="node"> 49<a name="Binary-constants"></a> 50<p> 51Previous: <a rel="previous" accesskey="p" href="Thread_002dLocal.html#Thread_002dLocal">Thread-Local</a>, 52Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a> 53<hr> 54</div> 55 56<h3 class="section">6.59 Binary constants using the ‘<samp><span class="samp">0b</span></samp>’ prefix</h3> 57 58<p><a name="index-Binary-constants-using-the-_0040samp_007b0b_007d-prefix-3252"></a> 59Integer constants can be written as binary constants, consisting of a 60sequence of ‘<samp><span class="samp">0</span></samp>’ and ‘<samp><span class="samp">1</span></samp>’ digits, prefixed by ‘<samp><span class="samp">0b</span></samp>’ or 61‘<samp><span class="samp">0B</span></samp>’. This is particularly useful in environments that operate a 62lot on the bit-level (like microcontrollers). 63 64 <p>The following statements are identical: 65 66<pre class="smallexample"> i = 42; 67 i = 0x2a; 68 i = 052; 69 i = 0b101010; 70</pre> 71 <p>The type of these constants follows the same rules as for octal or 72hexadecimal integer constants, so suffixes like ‘<samp><span class="samp">L</span></samp>’ or ‘<samp><span class="samp">UL</span></samp>’ 73can be applied. 74 75 </body></html> 76 77