You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
111 lines
4.8 KiB
HTML
111 lines
4.8 KiB
HTML
15 years ago
|
<!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' />
|
||
|
|
</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>
|
||
|
|
</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>
|