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191 lines
7.6 KiB
HTML
191 lines
7.6 KiB
HTML
14 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"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 - Sizeof </title>
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<link rel="shortcut icon" type="image/x-icon" href="http://arduino.cc/en/favicon.png">
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<link rel='stylesheet' href='arduinoUno.css' type='text/css' />
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<!--HeaderText--><style type='text/css'><!--
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ul, ol, pre, dl, p { margin-top:0px; margin-bottom:0px; }
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code { white-space: nowrap; }
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.vspace { margin-top:1.33em; }
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.indent { margin-left:40px; }
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.outdent { margin-left:40px; text-indent:-40px; }
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a.createlinktext { text-decoration:none; border-bottom:1px dotted gray; }
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a.createlink { text-decoration:none; position:relative; top:-0.5em;
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font-weight:bold; font-size:smaller; border-bottom:none; }
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img { border:0px; }
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span.anchor {
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float: left;
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font-size: 10px;
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margin-left: -10px;
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width: 10px;
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position:relative; top:-0.1em;
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text-align: center;
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}
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span.anchor a { text-decoration: none; }
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span.anchor a:hover { text-decoration: underline; }
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ol.toc { text-indent:-20px; list-style: none; }
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ol.toc ol.toc { text-indent:-40px; }
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div.tocfloat { font-size: smaller; margin-bottom: 10px;
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border-top: 1px dotted #555555; border-bottom: 1px dotted #555555;
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padding-top: 5px; padding-bottom: 5px;
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width: 38%; float: right; margin-left: 10px; clear: right;
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margin-right:-13px; padding-right: 13px; padding-left: 13px;
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background-color: #eeeeee; }
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div.toc { font-size: smaller;
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padding: 5px; border: 1px dotted #cccccc;
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background: #f7f7f7;
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margin-bottom: 10px; }
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div.toc p { background-color: #f9f6d6;
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margin-top:-5px; padding-top: 5px;
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margin-left:-5px; padding-left: 5px;
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margin-right:-5px; padding-right: 5px;
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padding-bottom: 3px;
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border-bottom: 1px dotted #cccccc; }.editconflict { color:green;
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font-style:italic; margin-top:1.33em; margin-bottom:1.33em; }
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table.markup { border: 2px dotted #ccf; width:90%; }
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td.markup1, td.markup2 { padding-left:10px; padding-right:10px; }
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td.markup1 { border-bottom: 1px solid #ccf; }
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div.faq { margin-left:2em; }
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div.faq p.question { margin: 1em 0 0.75em -2em; font-weight:bold; }
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div.faq hr { margin-left: -2em; }
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.frame
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{ border:1px solid #cccccc; padding:4px; background-color:#f9f9f9; }
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.lfloat { float:left; margin-right:0.5em; }
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.rfloat { float:right; margin-left:0.5em; }
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a.varlink { text-decoration:none; }
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--></style><script type="text/javascript">
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function toggle(obj) {
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var elstyle = document.getElementById(obj).style;
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var text = document.getElementById(obj + "tog");
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if (elstyle.display == 'none') {
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elstyle.display = 'block';
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text.innerHTML = "hide";
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} else {
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elstyle.display = 'none';
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text.innerHTML = "show";
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}
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}
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</script> <meta name='robots' content='index,follow' />
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<meta name="verify-v1" content="TtxFIEJAB6zdJ509wLxjnapQzKAMNm9u0Wj4ho6wxIY=" />
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</head>
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<body>
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<div id="page">
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<!--PageHeaderFmt-->
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<div id="pageheader">
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<div class="title"><a href='http://arduino.cc/en'>Arduino</a></div>
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<div class="search">
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<!-- SiteSearch Google -->
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<FORM method=GET action="http://www.google.com/search">
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<input type=hidden name=ie value=UTF-8>
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<input type=hidden name=oe value=UTF-8>
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<INPUT TYPE=text name=q size=25 maxlength=255 value="">
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<INPUT type=submit name=btnG VALUE="search">
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<input type=hidden name=domains value="http://www.arduino.cc/">
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<input type=hidden name=sitesearch value="http://www.arduino.cc/">
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</FORM>
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<!-- SiteSearch Google -->
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</div>
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</div>
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<!--/PageHeaderFmt-->
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<!--PageLeftFmt-->
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<div id="pagenav">
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<div id="navbar">
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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='http://arduino.cc/en/Tutorial/HomePage'>Learning</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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<a class='wikilink' href='FAQ.html'>FAQ</a>
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</p>
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<p class='vspace'></p>
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</div>
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<div id="navbar_external">
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<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>
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</div>
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</div>
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<!--/PageLeftFmt-->
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<div id="pagetext">
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<!--PageText-->
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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='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>sizeof</h2>
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<h4>Description</h4>
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<p>The sizeof operator returns the number of bytes in a variable type, or the number of bytes occupied by an array.
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</p>
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<p class='vspace'></p><h4>Syntax</h4>
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<p>sizeof(variable)
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</p>
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<p class='vspace'></p><h4>Parameters</h4>
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<p>variable: any variable type or array (e.g. int, float, byte)
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</p>
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<p class='vspace'></p><h4>Example code</h4>
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<p>The sizeof operator is useful for dealing with arrays (such as strings) where it is convenient to be able to change the size of the array without breaking other parts of the program.
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</p>
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<p class='vspace'></p><p>This program prints out a text string one character at a time. Try changing the text phrase.
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</p>
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<p class='vspace'></p><pre>
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char myStr[] = "this is a test";
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int i;
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void setup(){
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Serial.begin(9600);
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}
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void loop() {
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for (i = 0; i < sizeof(myStr) - 1; i++){
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Serial.print(i, DEC);
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Serial.print(" = ");
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Serial.println(myStr[i], BYTE);
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}
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}
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</pre><p>Note that sizeof returns the total number of bytes. So for larger variable types such as ints, the for loop would look something like this.
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</p>
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<p class='vspace'></p><pre>
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for (i = 0; i < (sizeof(myInts)/sizeof(int)) - 1; i++) {
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// do something with myInts[i]
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}
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</pre>
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<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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</div>
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<!-- AddThis Button BEGIN -->
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<script type="text/javascript">var addthis_language = "en";
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</script>
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<div class="addthis_container addthis_toolbox addthis_default_style" addthis:url="Sizeof" addthis:title="Arduino Wiki English">
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<a href="http://www.addthis.com/bookmark.php?v=250&username=arduinoteam" class="addthis_button_compact">Share</a><span
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class="addthis_separator">|</span><a class="addthis_button_email"></a><a class="addthis_button_favorites"></a><a class="addthis_button_print"></a><a
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class="addthis_button_facebook"></a><a class="addthis_button_twitter"></a><script type="text/javascript"
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src="http://s7.addthis.com/js/250/addthis_widget.js#username=arduinoteam"></script></div>
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<!-- AddThis Button END -->
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</div>
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<!--PageFooterFmt-->
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<div id="pagefooter">
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©Arduino |
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<a href=.html'#'>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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</div>
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<!--/PageFooterFmt-->
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</div>
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</body>
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</html>
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