<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title>Arduino - Boolean </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><h1>Boolean Operators </h1> <p>These can be used inside the condition of an <a class='wikilink' href='If.html'>if</a> statement. </p> <p class='vspace'></p><h3>&& (logical and)</h3> <p>True only if both operands are true, e.g. </p><pre> if (digitalRead(2) == HIGH && digitalRead(3) == HIGH) { // read two switches // ... } </pre><p>is true only if both inputs are high. </p> <p class='vspace'></p><h3>|| (logical or)</h3> <p>True if either operand is true, e.g. </p><pre> if (x > 0 || y > 0) { // ... } </pre><p>is true if either x or y is greater than 0. </p> <p class='vspace'></p><h3>! (not)</h3> <p>True if the operand is false, e.g. </p><pre> if (!x) { // ... } </pre><p>is true if x is false (i.e. if x equals 0). </p> <p class='vspace'></p><h4>Warning</h4> <p>Make sure you don't mistake the boolean AND operator, && (double ampersand) for the bitwise AND operator & (single ampersand). They are entirely different beasts. </p> <p class='vspace'></p><p>Similarly, do not confuse the boolean || (double pipe) operator with the bitwise OR operator | (single pipe). </p> <p class='vspace'></p><p>The bitwise not ~ (tilde) looks much different than the boolean not ! (exclamation point or "bang" as the programmers say) but you still have to be sure which one you want where. </p> <p class='vspace'></p><h4>Examples</h4> <pre> if (a >= 10 && a <= 20){} // true if a is between 10 and 20 </pre> <p class='vspace'></p><h4>See also</h4> <ul><li><a class='wikilink' href='BitwiseAnd.html'>&</a> (bitwise AND) </li><li><a class='wikilink' href='BitwiseAnd.html'>|</a> (bitwise OR) </li><li><a class='wikilink' href='BitwiseXorNot.html'>~</a> (bitwise NOT </li><li><a class='wikilink' href='If.html'>if</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>