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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Object Iteration</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.oop5.overloading.html">Overloading</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.oop5.patterns.html">Patterns</a></div> <div class="up"><a href="language.oop5.html">Classes and Objects (PHP 5)</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="language.oop5.iterations" class="sect1"> <h2 class="title">Object Iteration</h2> <p class="para"> PHP 5 provides a way for objects to be defined so it is possible to iterate through a list of items, with, for example a <a href="control-structures.foreach.html" class="link">foreach</a> statement. By default, all <a href="language.oop5.visibility.html" class="link">visible</a> properties will be used for the iteration. </p> <div class="example"> <p><b>Example #1 Simple Object Iteration</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyClass<br /></span><span style="color: #007700">{<br /> public </span><span style="color: #0000BB">$var1 </span><span style="color: #007700">= </span><span style="color: #DD0000">'value 1'</span><span style="color: #007700">;<br /> public </span><span style="color: #0000BB">$var2 </span><span style="color: #007700">= </span><span style="color: #DD0000">'value 2'</span><span style="color: #007700">;<br /> public </span><span style="color: #0000BB">$var3 </span><span style="color: #007700">= </span><span style="color: #DD0000">'value 3'</span><span style="color: #007700">;<br /><br /> protected </span><span style="color: #0000BB">$protected </span><span style="color: #007700">= </span><span style="color: #DD0000">'protected var'</span><span style="color: #007700">;<br /> private </span><span style="color: #0000BB">$private </span><span style="color: #007700">= </span><span style="color: #DD0000">'private var'</span><span style="color: #007700">;<br /><br /> function </span><span style="color: #0000BB">iterateVisible</span><span style="color: #007700">() {<br /> echo </span><span style="color: #DD0000">"MyClass::iterateVisible:\n"</span><span style="color: #007700">;<br /> foreach(</span><span style="color: #0000BB">$this </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> print </span><span style="color: #DD0000">"$key => $value\n"</span><span style="color: #007700">;<br /> }<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$class </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyClass</span><span style="color: #007700">();<br /><br />foreach(</span><span style="color: #0000BB">$class </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> print </span><span style="color: #DD0000">"$key => $value\n"</span><span style="color: #007700">;<br />}<br />echo </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /><br /></span><span style="color: #0000BB">$class</span><span style="color: #007700">-></span><span style="color: #0000BB">iterateVisible</span><span style="color: #007700">();<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents"><pre><div class="cdata"><pre>var1 => value 1var2 => value 2var3 => value 3MyClass::iterateVisible:var1 => value 1var2 => value 2var3 => value 3protected => protected varprivate => private var</pre></div> </pre></div> </div> <p class="para"> As the output shows, the <a href="control-structures.foreach.html" class="link">foreach</a> iterated through all <a href="language.oop5.visibility.html" class="link">visible</a> variables that can be accessed. To take it a step further you can <var class="varname">implement</var> one of PHP 5's internal <a href="language.oop5.interfaces.html" class="link">interface</a> named <var class="varname">Iterator</var>. This allows the object to decide what and how the object will be iterated. </p> <div class="example"> <p><b>Example #2 Object Iteration implementing Iterator</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyIterator </span><span style="color: #007700">implements </span><span style="color: #0000BB">Iterator<br /></span><span style="color: #007700">{<br /> private </span><span style="color: #0000BB">$var </span><span style="color: #007700">= array();<br /><br /> public function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">)<br /> {<br /> if (</span><span style="color: #0000BB">is_array</span><span style="color: #007700">(</span><span style="color: #0000BB">$array</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">var </span><span style="color: #007700">= </span><span style="color: #0000BB">$array</span><span style="color: #007700">;<br /> }<br /> }<br /><br /> public function </span><span style="color: #0000BB">rewind</span><span style="color: #007700">() {<br /> echo </span><span style="color: #DD0000">"rewinding\n"</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">reset</span><span style="color: #007700">(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">);<br /> }<br /><br /> public function </span><span style="color: #0000BB">current</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #0000BB">current</span><span style="color: #007700">(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">);<br /> echo </span><span style="color: #DD0000">"current: $var\n"</span><span style="color: #007700">;<br /> return </span><span style="color: #0000BB">$var</span><span style="color: #007700">;<br /> }<br /><br /> public function </span><span style="color: #0000BB">key</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #0000BB">key</span><span style="color: #007700">(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">);<br /> echo </span><span style="color: #DD0000">"key: $var\n"</span><span style="color: #007700">;<br /> return </span><span style="color: #0000BB">$var</span><span style="color: #007700">;<br /> }<br /><br /> public function </span><span style="color: #0000BB">next</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #0000BB">next</span><span style="color: #007700">(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">var</span><span style="color: #007700">);<br /> echo </span><span style="color: #DD0000">"next: $var\n"</span><span style="color: #007700">;<br /> return </span><span style="color: #0000BB">$var</span><span style="color: #007700">;<br /> }<br /><br /> public function </span><span style="color: #0000BB">valid</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">$var </span><span style="color: #007700">= </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">current</span><span style="color: #007700">() !== </span><span style="color: #0000BB">false</span><span style="color: #007700">;<br /> echo </span><span style="color: #DD0000">"valid: {$var}\n"</span><span style="color: #007700">;<br /> return </span><span style="color: #0000BB">$var</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$values </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">,</span><span style="color: #0000BB">2</span><span style="color: #007700">,</span><span style="color: #0000BB">3</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$it </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyIterator</span><span style="color: #007700">(</span><span style="color: #0000BB">$values</span><span style="color: #007700">);<br /><br />foreach (</span><span style="color: #0000BB">$it </span><span style="color: #007700">as </span><span style="color: #0000BB">$a </span><span style="color: #007700">=> </span><span style="color: #0000BB">$b</span><span style="color: #007700">) {<br /> print </span><span style="color: #DD0000">"$a: $b\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents"><pre><div class="cdata"><pre>rewindingcurrent: 1valid: 1current: 1key: 00: 1next: 2current: 2valid: 1⌨️ 快捷键说明
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