<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title>Arduino Reference - ServerAvailable </title> <link rel="shortcut icon" type="image/x-icon" href="http://arduino.cc/en/favicon.png"> <link rel='stylesheet' href='arduinoWideRender.css' type='text/css' /> <!--HeaderText--><style type='text/css'><!-- ul, ol, pre, dl, p { margin-top:0px; margin-bottom:0px; } code { white-space: nowrap; } .vspace { margin-top:1.33em; } .indent { margin-left:40px; } .outdent { margin-left:40px; text-indent:-40px; } a.createlinktext { text-decoration:none; border-bottom:1px dotted gray; } a.createlink { text-decoration:none; position:relative; top:-0.5em; font-weight:bold; font-size:smaller; border-bottom:none; } img { border:0px; } .editconflict { color:green; font-style:italic; margin-top:1.33em; margin-bottom:1.33em; } table.markup { border: 2px dotted #ccf; width:90%; } td.markup1, td.markup2 { padding-left:10px; padding-right:10px; } td.markup1 { border-bottom: 1px solid #ccf; } div.faq { margin-left:2em; } div.faq p.question { margin: 1em 0 0.75em -2em; font-weight:bold; } div.faq hr { margin-left: -2em; } .frame { border:1px solid #cccccc; padding:4px; background-color:#f9f9f9; } .lfloat { float:left; margin-right:0.5em; } .rfloat { float:right; margin-left:0.5em; } a.varlink { text-decoration:none; } /** * GeSHi (C) 2004 - 2007 Nigel McNie, 2007 - 2008 Benny Baumann * (http://qbnz.com/highlighter/ and http://geshi.org/) */ .arduino {font-family:monospace;} .arduino .imp {font-weight: bold; color: red;} .arduino .kw1 {color: #CC6600;} .arduino .kw2 {color: #006699;} .arduino .kw3 {color: #CC6600; font-weight: bold;} .arduino .co1 {color: #7E7E7E; font-style: italic;} .arduino .co2 {color: #7E7E7E;} .arduino .coMULTI {color: #7E7E7E; font-style: italic;} .arduino .es0 {color: #000099; font-weight: bold;} .arduino .es1 {color: #000099; font-weight: bold;} .arduino .es2 {color: #660099; font-weight: bold;} .arduino .es3 {color: #660099; font-weight: bold;} .arduino .es4 {color: #660099; font-weight: bold;} .arduino .es5 {color: #006699; font-weight: bold;} .arduino .br0 {color: #000000;} .arduino .sy0 {color: #000000;} .arduino .st0 {color: #0066CC;} .arduino .nu0 {color: #000000;} .arduino .nu6 {color: #208080;} .arduino .nu8 {color: #208080;} .arduino .nu12 {color: #208080;} .arduino .nu16 {color:#800080;} .arduino .nu17 {color:#800080;} .arduino .nu18 {color:#800080;} .arduino .nu19 {color:#800080;} .arduino .me1 {color: #ff1493;} .arduino .me2 {color: #ff1493;} .arduino span.xtra { display:block; } .sourceblocklink { text-align: right; font-size: smaller; } .sourceblocktext { padding: 0.5em; color: #000000; background-color: #ffffff; } .sourceblocktext div { font-family: monospace; font-size: small; line-height: 1; height: 1%; } .sourceblocktext div.head, .sourceblocktext div.foot { font: italic medium serif; padding: 0.5em; } --></style> <meta name='robots' content='index,follow' /> <meta name="verify-v1" content="TtxFIEJAB6zdJ509wLxjnapQzKAMNm9u0Wj4ho6wxIY=" /> </head> <body> <div id="page"> <!--PageHeaderFmt--> <div id="pageheader"> <div class="title"><a href='http://arduino.cc/en'>Arduino</a></div> </div> <!--/PageHeaderFmt--> <!--PageLeftFmt--> <div id="pagenav"> <div id="navbar"> <p><a class='wikilink' href='http://arduino.cc/en/Main/Buy'>Buy</a> <a class='wikilink' href='http://arduino.cc/en/Main/Software'>Download</a> <a class='wikilink' href='Guide_index.html'>Getting Started</a> <a class='wikilink' href='http://arduino.cc/en/Tutorial/HomePage'>Learning</a> <a class='wikilink' href='index.html'>Reference</a> <a class='wikilink' href='http://arduino.cc/en/Main/Hardware'>Hardware</a> <a class='wikilink' href='FAQ.html'>FAQ</a> </p> <p class='vspace'></p> </div> </div> <!--/PageLeftFmt--> <div id="pagetext"> <!--PageText--> <div id='wikitext'> <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> </p> <p class='vspace'></p><p><a class='wikilink' href='Ethernet.html'>Ethernet</a> : <em>Server</em> class </p> <p class='vspace'></p><h2>available()</h2> <h4>Description</h4> <p>Gets a client that is connected to the server and has data available for reading. The connection persists when the returned client object goes out of scope; you can close it by calling <em>client</em>.stop(). </p> <p class='vspace'></p><p>available() inherits from the <a class='wikilink' href='Stream.html'>Stream</a> utility class. </p> <p class='vspace'></p><h4>Syntax</h4> <p><em>server</em>.available() </p> <p class='vspace'></p><h4>Parameters</h4> <p>None </p> <p class='vspace'></p><h4>Returns</h4> <p>a Client object; if no Client has data available for reading, this object will evaluate to false in an if-statement (see the example below) </p> <p class='vspace'></p><h4>Example</h4> <p> <div class='sourceblock ' id='sourceblock1'> <div class='sourceblocktext'><div class="arduino"><span class="co2">#include <Ethernet.h></span><br /> <span class="co2">#include <SPI.h></span><br /> <br /> <span class="co1">// the media access control (ethernet hardware) address for the shield:</span><br /> <span class="kw1">byte</span> mac<span class="br0">[</span><span class="br0">]</span> <span class="sy0">=</span> <span class="br0">{</span> <span class="nu12">0xDE</span><span class="sy0">,</span> <span class="nu12">0xAD</span><span class="sy0">,</span> <span class="nu12">0xBE</span><span class="sy0">,</span> <span class="nu12">0xEF</span><span class="sy0">,</span> <span class="nu12">0xFE</span><span class="sy0">,</span> <span class="nu12">0xED</span> <span class="br0">}</span><span class="sy0">;</span> <br /> <span class="co1">//the IP address for the shield:</span><br /> <span class="kw1">byte</span> ip<span class="br0">[</span><span class="br0">]</span> <span class="sy0">=</span> <span class="br0">{</span> <span class="nu0">10</span><span class="sy0">,</span> <span class="nu0">0</span><span class="sy0">,</span> <span class="nu0">0</span><span class="sy0">,</span> <span class="nu0">177</span> <span class="br0">}</span><span class="sy0">;</span> <br /> <span class="co1">// the router's gateway address:</span><br /> <span class="kw1">byte</span> gateway<span class="br0">[</span><span class="br0">]</span> <span class="sy0">=</span> <span class="br0">{</span> <span class="nu0">10</span><span class="sy0">,</span> <span class="nu0">0</span><span class="sy0">,</span> <span class="nu0">0</span><span class="sy0">,</span> <span class="nu0">1</span> <span class="br0">}</span><span class="sy0">;</span><br /> <span class="co1">// the subnet:</span><br /> <span class="kw1">byte</span> subnet<span class="br0">[</span><span class="br0">]</span> <span class="sy0">=</span> <span class="br0">{</span> <span class="nu0">255</span><span class="sy0">,</span> <span class="nu0">255</span><span class="sy0">,</span> <span class="nu0">0</span><span class="sy0">,</span> <span class="nu0">0</span> <span class="br0">}</span><span class="sy0">;</span><br /> <br /> <br /> <span class="co1">// telnet defaults to port 23</span><br /> EthernetServer server <span class="sy0">=</span> EthernetServer<span class="br0">(</span><span class="nu0">23</span><span class="br0">)</span><span class="sy0">;</span><br /> <br /> <span class="kw1">void</span> <span class="kw3">setup</span><span class="br0">(</span><span class="br0">)</span><br /> <span class="br0">{</span><br /> <span class="co1">// initialize the ethernet device</span><br /> Ethernet.<span class="kw1">begin</span><span class="br0">(</span>mac<span class="sy0">,</span> ip<span class="sy0">,</span> gateway<span class="sy0">,</span> subnet<span class="br0">)</span><span class="sy0">;</span><br /> <br /> <span class="co1">// start listening for clients</span><br /> server.<span class="kw1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span><br /> <span class="br0">}</span><br /> <br /> <span class="kw1">void</span> <span class="kw3">loop</span><span class="br0">(</span><span class="br0">)</span><br /> <span class="br0">{</span><br /> <span class="co1">// if an incoming client connects, there will be bytes available to read:</span><br /> EthernetClient client <span class="sy0">=</span> server.<span class="kw1">available</span><span class="br0">(</span><span class="br0">)</span><span class="sy0">;</span><br /> <span class="kw1">if</span> <span class="br0">(</span>client <span class="sy0">==</span> <span class="kw1">true</span><span class="br0">)</span> <span class="br0">{</span><br /> <span class="co1">// read bytes from the incoming client and write them back</span><br /> <span class="co1">// to any clients connected to the server:</span><br /> server.<span class="kw1">write</span><span class="br0">(</span>client.<span class="kw1">read</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy0">;</span><br /> <span class="br0">}</span><br /> <span class="br0">}</span></div></div> <div class='sourceblocklink'><a href='#' type='text/plain'>[Get Code]</a></div> </div> </p> <p class='vspace'></p><h4>See Also</h4> <ul><li><a class='wikilink' href='StreamAvailable.html'>Stream.available()</a> </li></ul><p><a class='wikilink' href='index.html'>Reference Home</a> </p> <p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://arduino.cc/forum/index.php/board,23.0.html' rel='nofollow'>Forum</a>.</em> </p> <p class='vspace'></p><p>The text of the Arduino reference is licensed under a <a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>. 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