99 lines
4.9 KiB
HTML
99 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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<head>
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<title>Arduino - Float </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 id="page">
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<div id="pageheader">
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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='http://arduino.cc/en/Main/Software'>Download</a>
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<a class='wikilink' href='Guide_index.html'>Getting Started</a>
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<a class='wikilink' href='index.html'>Reference</a>
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<a class='wikilink' href='http://arduino.cc/en/Main/Hardware'>Hardware</a>
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<p class='vspace'></p>
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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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<a class="urllink" href="http://www.arduino.cc/playground/" rel="nofollow">Playground »</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><h2>float</h2>
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<h4>Description </h4>
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<p>Datatype for floating-point numbers, a number that has a decimal point. Floating-point numbers are often used to approximate analog and continuous values because they have greater resolution than integers. Floating-point numbers can be as large as 3.4028235E+38 and as low as -3.4028235E+38. They are stored as 32 bits (4 bytes) of information.
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</p>
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<p class='vspace'></p><p>Floating point numbers are not exact, and may yield strange results when compared. For example <code>6.0 / 3.0</code> may not equal <code>2.0</code>. You should instead check that the absolute value of the difference between the numbers is less than some small number.
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</p>
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<p class='vspace'></p><p>Floating point math is also much slower than integer math in performing calculations, so should be avoided if, for example, a loop has to run at top speed for a critical timing function. Programmers often go to some lengths to convert floating point calculations to integer math to increase speed.
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</p>
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<p class='vspace'></p><h4>Examples</h4>
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<pre> float myfloat;
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float sensorCalbrate = 1.117;
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</pre>
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<p class='vspace'></p><h4>Syntax</h4>
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<pre> float var = val;
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</pre>
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<p class='vspace'></p><ul><li>var - your float variable name
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</li><li>val - the value you assign to that variable
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</li></ul><p class='vspace'></p><h4>Example Code</h4>
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<pre>
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int x;
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int y;
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float z;
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x = 1;
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y = x / 2; // y now contains 0, ints can't hold fractions
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z = (float)x / 2.0; // z now contains .5 (you have to use 2.0, not 2)
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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='Int.html'>int</a>
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</li><li><a class='wikilink' href='Double.html'>double</a>
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</li><li><a class='urllink' href='VariableDeclaration.html' rel='nofollow'>Variable Declaration</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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<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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