112 lines
4.9 KiB
HTML
112 lines
4.9 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html>
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<title>Arduino - Boolean </title>
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<div class="title"><a href="http://www.arduino.cc"/>Arduino</a></div>
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<a class="urllink" href="http://www.arduino.cc/blog/" rel="nofollow">Blog »</a> |
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<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>
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</p>
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<p class='vspace'></p><h1>Boolean Operators </h1>
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<p>These can be used inside the condition of an <a class='wikilink' href='If.html'>if</a> statement.
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</p>
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<p class='vspace'></p><h3>&& (logical and)</h3>
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<p>True only if both operands are true, e.g.
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</p><pre>
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if (digitalRead(2) == HIGH && digitalRead(3) == HIGH) { // read two switches
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// ...
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}
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</pre><p>is true only if both inputs are high.
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</p>
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<p class='vspace'></p><h3>|| (logical or)</h3>
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<p>True if either operand is true, e.g.
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</p><pre>
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if (x > 0 || y > 0) {
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// ...
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}
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</pre><p>is true if either x or y is greater than 0.
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</p>
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<p class='vspace'></p><h3>! (not)</h3>
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<p>True if the operand is false, e.g.
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</p><pre>
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if (!x) {
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// ...
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}
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</pre><p>is true if x is false (i.e. if x equals 0).
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</p>
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<p class='vspace'></p><h4>Warning</h4>
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<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.
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</p>
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<p class='vspace'></p><p>Similarly, do not confuse the boolean || (double pipe) operator with the bitwise OR operator | (single pipe).
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</p>
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<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.
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</p>
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<p class='vspace'></p><h4>Examples</h4>
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<pre>
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if (a >= 10 && a <= 20){} // true if a is between 10 and 20
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</pre>
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<p class='vspace'></p><h4>See also</h4>
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<ul><li><a class='wikilink' href='BitwiseAnd.html'>&</a> (bitwise AND)
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</li><li><a class='wikilink' href='BitwiseAnd.html'>|</a> (bitwise OR)
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</li><li><a class='wikilink' href='BitwiseXorNot.html'>~</a> (bitwise NOT
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</li><li><a class='wikilink' href='If.html'>if</a>
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</li></ul><p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a>
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</p>
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<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>
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</p>
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<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
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<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.
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</p>
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