101 lines
5.2 KiB
HTML
101 lines
5.2 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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<head>
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<title>Arduino - Arithmetic </title>
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<link rel='stylesheet' href='arduino.css' type='text/css' />
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<meta name="verify-v1" content="TtxFIEJAB6zdJ509wLxjnapQzKAMNm9u0Wj4ho6wxIY=" />
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<div class="title"><a href="http://www.arduino.cc"/>Arduino</a></div>
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<p><a class='wikilink' href='http://arduino.cc/en/Main/Buy'>Buy</a>
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<a class='wikilink' href='index.html'>Reference</a>
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</div>
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<a class="urllink" href="http://www.arduino.cc/blog/" rel="nofollow">Blog »</a> |
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<a class="urllink" href="http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl" rel="nofollow">Forum »</a> |
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<div id='wikitext'>
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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><h2>Addition, Subtraction, Multiplication, & Division</h2>
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<h4>Description</h4>
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<p>These operators return the sum, difference, product, or quotient (respectively) of the two operands. The operation is conducted using the data type of the operands, so, for example, <code>9 / 4</code> gives <code>2</code> since 9 and 4 are ints. This also means that the operation can overflow if the result is larger than that which can be stored in the data type (e.g. adding 1 to an <a class='wikilink' href='Int.html'>int</a> with the value 32,767 gives -32,768). If the operands are of different types, the "larger" type is used for the calculation.
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</p>
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<p class='vspace'></p><p>If one of the numbers (operands) are of the type <strong>float</strong> or of type <strong>double</strong>, floating point math will be used for the calculation.
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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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y = y + 3;
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x = x - 7;
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i = j * 6;
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r = r / 5;
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</pre>
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<p class='vspace'></p><h4>Syntax</h4>
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<pre>
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result = value1 + value2;
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result = value1 - value2;
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result = value1 * value2;
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result = value1 / value2;
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</pre>
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<p class='vspace'></p><h4>Parameters:</h4>
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<p>value1: any variable or constant
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</p>
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<p class='vspace'></p><p>value2: any variable or constant
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</p>
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<p class='vspace'></p><h4>Programming Tips:</h4>
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<ul><li>Know that <a class='wikilink' href='IntegerConstants.html'>integer constants</a> default to <a class='wikilink' href='Int.html'>int</a>, so some constant calculations may overflow (e.g. 60 * 1000 will yield a negative result).
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<p class='vspace'></p></li><li>Choose variable sizes that are large enough to hold the largest results from your calculations
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<p class='vspace'></p></li><li>Know at what point your variable will "roll over" and also what happens in the other direction e.g. (0 - 1) OR (0 - - 32768)
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<p class='vspace'></p></li><li>For math that requires fractions, use float variables, but be aware of their drawbacks: large size, slow computation speeds
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<p class='vspace'></p></li><li>Use the cast operator e.g. (int)myFloat to convert one variable type to another on the fly.
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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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<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>
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