function.array-key-exists.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Prüft, ob ein Schlüssel in einem Array existiert</title>
</head>
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</div><hr /><div id="function.array-key-exists" class="refentry">
<div class="refnamediv">
<h1 class="refname">array_key_exists</h1>
<p class="verinfo">(PHP 4 >= 4.0.7, PHP 5)</p><p class="refpurpose"><span class="refname">array_key_exists</span> — <span class="dc-title">Prüft, ob ein Schlüssel in einem Array existiert</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.array-key-exists-description">
<h3 class="title">Beschreibung</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>array_key_exists</strong></span>
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$key</code></span>
, <span class="methodparam"><span class="type">array</span> <code class="parameter">$search</code></span>
)</div>
<p class="para rdfs-comment">
<span class="function"><strong>array_key_exists()</strong></span> gibt <strong><code>TRUE</code></strong> zurück, wenn
<code class="parameter">key</code> in dem Array vorhanden ist.
<code class="parameter">key</code> kann jeder für einen Array-Index
mögliche Wert sein.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.array-key-exists-parameters">
<h3 class="title">Parameter-Liste</h3>
<p class="para">
<dl>
<dt>
<code class="parameter">key</code></dt>
<dd>
<p class="para">
Der zu prüfende Wert.
</p>
</dd>
<dt>
<code class="parameter">search</code></dt>
<dd>
<p class="para">
Ein Array mit den zu prüfenden Schlüsseln.
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.array-key-exists-returnvalues">
<h3 class="title">Rückgabewerte</h3>
<p class="para">
Gibt bei Erfolg <strong><code>TRUE</code></strong> zurück. Im Fehlerfall wird <strong><code>FALSE</code></strong> zurückgegeben.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.array-key-exists-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Beschreibung</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>5.3.0</td>
<td>
Diese Funktion arbeitet nicht mehr mit Objekten.
<span class="function"><a href="function.property-exists.html" class="function">property_exists()</a></span> sollte in diesem Fall
genutzt werden.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.array-key-exists-examples">
<h3 class="title">Beispiele</h3>
<p class="para">
<div class="example" id="example-4913">
<p><strong>Beispiel #1 <span class="function"><strong>array_key_exists()</strong></span>-Beispiel</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$search_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'erstes' </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'zweites' </span><span style="color: #007700">=> </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br />if (</span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'erstes'</span><span style="color: #007700">, </span><span style="color: #0000BB">$search_array</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Das Element 'erstes' ist in dem Array vorhanden"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<div class="example" id="example-4914">
<p><strong>Beispiel #2 <span class="function"><strong>array_key_exists()</strong></span> vs. <span class="function"><a href="function.isset.html" class="function">isset()</a></span></strong></p>
<div class="example-contents"><p>
<span class="function"><a href="function.isset.html" class="function">isset()</a></span> gibt nicht <strong><code>TRUE</code></strong> zurück für Schlüssel eines
Arrays, die zu einem <strong><code>NULL</code></strong>-Wert gehören,
<span class="function"><strong>array_key_exists()</strong></span> tut dies hingegen.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$search_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'erstes' </span><span style="color: #007700">=> </span><span style="color: #0000BB">null</span><span style="color: #007700">, </span><span style="color: #DD0000">'zweites' </span><span style="color: #007700">=> </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Gibt false zurück<br /></span><span style="color: #007700">isset(</span><span style="color: #0000BB">$search_array</span><span style="color: #007700">[</span><span style="color: #DD0000">'erstes'</span><span style="color: #007700">]);<br /><br /></span><span style="color: #FF8000">// Gibt true zurück<br /></span><span style="color: #0000BB">array_key_exists</span><span style="color: #007700">(</span><span style="color: #DD0000">'erstes'</span><span style="color: #007700">, </span><span style="color: #0000BB">$search_array</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</div>
<div class="refsect1 notes" id="refsect1-function.array-key-exists-notes">
<h3 class="title">Anmerkungen</h3>
<blockquote class="note"><p><strong class="note">Hinweis</strong>:
<p class="para">
Für die Abwärtskompatibiliät kann der
folgende veraltete Alias verwendet werden:
<span class="function"><a href="function.key-exists.html" class="function">key_exists()</a></span>
</p>
</p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.array-key-exists-seealso">
<h3 class="title">Siehe auch</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><span class="function"><a href="function.isset.html" class="function" rel="rdfs-seeAlso">isset()</a> - Prüft, ob eine Variable existiert und ob sie nicht NULL ist</span></li>
<li class="member"><span class="function"><a href="function.array-keys.html" class="function" rel="rdfs-seeAlso">array_keys()</a> - Liefert alle Schlüssel oder eine Teilmenge aller Schlüssel eines Arrays</span></li>
<li class="member"><span class="function"><a href="function.in-array.html" class="function" rel="rdfs-seeAlso">in_array()</a> - Prüft, ob ein Wert in einem Array existiert</span></li>
<li class="member"><span class="function"><a href="function.property-exists.html" class="function" rel="rdfs-seeAlso">property_exists()</a> - Prüft auf die Existenz einer Eigenschaft eines Objektes bzw. einer Klasse</span></li>
</ul>
</p>
</div>
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