<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title>Arduino - IntegerConstants </title> <link rel='stylesheet' href='arduino.css' type='text/css' /> <meta name="verify-v1" content="TtxFIEJAB6zdJ509wLxjnapQzKAMNm9u0Wj4ho6wxIY=" /> </head> <body> <div id="page"> <!--PageHeaderFmt--> <div id="pageheader"> <div class="title"><a href="http://www.arduino.cc"/>Arduino</a></div> <div class="search"> <!-- SiteSearch Google --> <FORM method=GET action="http://www.google.com/search"> <input type=hidden name=ie value=UTF-8> <input type=hidden name=oe value=UTF-8> <INPUT TYPE=text name=q size=25 maxlength=255 value=""> <INPUT type=submit name=btnG VALUE="search"> <input type=hidden name=domains value="http://www.arduino.cc/"> <input type=hidden name=sitesearch value="http://www.arduino.cc/"> </FORM> <!-- SiteSearch Google --> </div> </div> <!--/PageHeaderFmt--> <!--PageLeftFmt--> <div id="pagenav" style="text-align: right"> <div style="float: left;"> <p><a class='wikilink' href='http://arduino.cc/en/Main/Buy'>Buy</a> | <a class='wikilink' href='http://arduino.cc/en/Main/Software'>Download</a> | <a class='wikilink' href='Guide_index.html'>Getting Started</a> | <a class='wikilink' href='http://arduino.cc/en/Tutorial/HomePage'>Learning</a> | <a class='wikilink' href='index.html'>Reference</a> | <a class='wikilink' href='http://arduino.cc/en/Main/Hardware'>Hardware</a> | <a class='wikilink' href='FAQ.html'>FAQ</a> </p> <p class='vspace'></p> </div> <a class="urllink" href="http://www.arduino.cc/blog/" rel="nofollow">Blog »</a> | <a class="urllink" href="http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl" rel="nofollow">Forum »</a> | <a class="urllink" href="http://www.arduino.cc/playground/" rel="nofollow">Playground »</a> </div> <!--/PageLeftFmt--> <div id="pagetext"> <!--PageText--> <div id='wikitext'> <p><strong>Reference</strong> <a class='wikilink' href='index.html'>Language</a> (<a class='wikilink' href='Extended.html'>extended</a>) | <a class='wikilink' href='Libraries.html'>Libraries</a> | <a class='wikilink' href='Comparison.html'>Comparison</a> | <a class='wikilink' href='Changes.html'>Changes</a> </p> <p class='vspace'></p><h2>Integer Constants</h2> <p>Integer constants are numbers used directly in a sketch, like <code>123</code>. By default, these numbers are treated as <a class='wikilink' href='Int.html'>int</a>'s but you can change this with the U and L modifiers (see below). </p> <p class='vspace'></p><p>Normally, integer constants are treated as base 10 (decimal) integers, but special notation (formatters) may be used to enter numbers in other bases. </p> <p class='vspace'></p><pre> Base Example Formatter Comment 10 (decimal) 123 none 2 (binary) B1111011 leading 'B' only works with 8 bit values (0 to 255) characters 0-1 valid 8 (octal) 0173 leading "0" characters 0-7 valid 16 (hexadecimal) 0x7B leading "0x" characters 0-9, A-F, a-f valid </pre> <p class='vspace'></p><p><strong>Decimal</strong> is base 10. This is the common-sense math with which you are acquainted. Constants without other prefixes are assumed to be in decimal format. </p> <p class='vspace'></p>Example:<pre> 101 // same as 101 decimal ((1 * 10^2) + (0 * 10^1) + 1) </pre> <p><br /> <strong>Binary</strong> is base two. Only characters 0 and 1 are valid. </p> <p class='vspace'></p>Example:<pre> B101 // same as 5 decimal ((1 * 2^2) + (0 * 2^1) + 1) </pre> <p>The binary formatter only works on bytes (8 bits) between 0 (B0) and 255 (B11111111). If it is convenient to input an int (16 bits) in binary form you can do it a two-step procedure such as: </p> <p class='vspace'></p><pre> myInt = (B11001100 * 256) + B10101010; // B11001100 is the high byte </pre> <p class='vspace'></p><p><strong>Octal</strong> is base eight. Only characters 0 through 7 are valid. Octal values are indicated by the prefix "0" </p> <p class='vspace'></p><p>Example: </p><pre> 0101 // same as 65 decimal ((1 * 8^2) + (0 * 8^1) + 1) </pre><div class='indent'>Warning </div><div class='indent'>It is possible to generate a hard-to-find bug by (unintentionally) including a leading zero before a constant and having the compiler unintentionally interpret your constant as octal. </div><p><br /> <strong>Hexadecimal (or hex)</strong> is base sixteen. Valid characters are 0 through 9 and letters A through F; A has the value 10, B is 11, up to F, which is 15. Hex values are indicated by the prefix "0x". Note that A-F may be syted in upper or lower case (a-f). </p> <p class='vspace'></p><p>Example: </p><pre> 0x101 // same as 257 decimal ((1 * 16^2) + (0 * 16^1) + 1) </pre> <p class='vspace'></p><h4>U & L formatters</h4> <p>By default, an integer constant is treated as an <a class='wikilink' href='Int.html'>int</a> with the attendant limitations in values. To specify an integer constant with another data type, follow it with: </p> <p class='vspace'></p><ul><li>a 'u' or 'U' to force the constant into an unsigned data format. Example: <code>33u</code> </li><li>a 'l' or 'L' to force the constant into a long data format. Example: <code>100000L</code> </li><li>a 'ul' or 'UL' to force the constant into an unsigned long constant. Example: <code>32767ul</code> </li></ul><p><br /> </p> <p class='vspace'></p><h4>See also</h4> <ul><li><a class='wikilink' href='Constants.html'>constants</a> </li><li><a class='wikilink' href='Define.html'>#define</a> </li><li><a class='wikilink' href='Byte.html'>byte</a> </li><li><a class='wikilink' href='Int.html'>int</a> </li><li><a class='wikilink' href='UnsignedInt.html'>unsigned int</a> </li><li><a class='wikilink' href='Long.html'>long</a> </li><li><a class='wikilink' href='UnsignedLong.html'>unsigned long</a> </li></ul><p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a> </p> <p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?board=swbugs' rel='nofollow'>Forum</a>.</em> </p> <p class='vspace'></p><p>The text of the Arduino reference is licensed under a <a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>. Code samples in the reference are released into the public domain. </p> </div> </div> <!--PageFooterFmt--> <div id="pagefooter"> <a href='#'>Edit Page</a> | <a href='#'>Page History</a> | <a href='#' target='_blank'>Printable View</a> | <a href='http://arduino.cc/en/Site/AllRecentChanges'>All Recent Site Changes</a> </div> <!--/PageFooterFmt--> </div> </body> </html>