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187 lines
8.0 KiB
HTML
187 lines
8.0 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 - Else </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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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>if / else</h2>
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<p><strong>if/else</strong> allows greater control over the flow of code than the basic <strong>if</strong> statement, by allowing multiple tests to be grouped together. For example, an analog input could be tested and one action taken if the input was less than 500, and another action taken if the input was 500 or greater. The code would look like this:
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</p>
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<p class='vspace'></p><pre>if (pinFiveInput < 500)
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{
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// action A
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}
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else
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{
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// action B
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}
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</pre>
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<p class='vspace'></p><p><strong>else</strong> can proceed another <strong>if</strong> test, so that multiple, mutually exclusive tests can be run at the same time.
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</p>
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<p class='vspace'></p><p>Each test will proceed to the next one until a true test is encountered. When a true test is found, its associated block of code is run, and the program then skips to the line following the entire if/else construction. If no test proves to be true, the default <strong>else</strong> block is executed, if one is present, and sets the default behavior.
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</p>
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<p class='vspace'></p><p>Note that an <strong>else if</strong> block may be used with or without a terminating <strong>else</strong> block and vice versa. An unlimited number of such <strong>else if</strong> branches is allowed.
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</p>
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<p class='vspace'></p><pre>if (pinFiveInput < 500)
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{
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// do Thing A
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}
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else if (pinFiveInput >= 1000)
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{
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// do Thing B
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}
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else
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{
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// do Thing C
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}
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</pre><p>Another way to express branching, mutually exclusive tests, is with the <a class='wikilink' href='SwitchCase.html'>switch case</a> statement.
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</p>
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<p class='vspace'></p><h4>See also:</h4>
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<p><a class='wikilink' href='SwitchCase.html'>switch case</a>
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</p>
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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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<div class="addthis_container addthis_toolbox addthis_default_style" addthis:url="Else" 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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©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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