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<title>Calculate the soundex key of a string</title>
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<h1 class="refname">soundex</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">soundex</span> — <span class="dc-title">Calculate the soundex key of a string</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.soundex-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">string</span> <span class="methodname"><strong>soundex</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$str</code></span>
)</div>
<p class="para rdfs-comment">
Calculates the soundex key of <em><code class="parameter">str</code></em>.
</p>
<p class="para">
Soundex keys have the property that words pronounced similarly
produce the same soundex key, and can thus be used to simplify
searches in databases where you know the pronunciation but not
the spelling. This soundex function returns a string 4 characters
long, starting with a letter.
</p>
<p class="para">
This particular soundex function is one described by Donald Knuth
in "The Art Of Computer Programming, vol. 3: Sorting And
Searching", Addison-Wesley (1973), pp. 391-392.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.soundex-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">str</code></em></span>
<dd>
<p class="para">
The input string.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.soundex-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the soundex key as a string.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.soundex-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-4862">
<p><strong>Example #1 Soundex Examples</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Euler"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Ellery"</span><span style="color: #007700">); </span><span style="color: #FF8000">// E460<br /></span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Gauss"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Ghosh"</span><span style="color: #007700">); </span><span style="color: #FF8000">// G200<br /></span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Hilbert"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Heilbronn"</span><span style="color: #007700">); </span><span style="color: #FF8000">// H416<br /></span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Knuth"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Kant"</span><span style="color: #007700">); </span><span style="color: #FF8000">// K530<br /></span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Lloyd"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Ladd"</span><span style="color: #007700">); </span><span style="color: #FF8000">// L300<br /></span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Lukasiewicz"</span><span style="color: #007700">) == </span><span style="color: #0000BB">soundex</span><span style="color: #007700">(</span><span style="color: #DD0000">"Lissajous"</span><span style="color: #007700">); </span><span style="color: #FF8000">// L222<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.soundex-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.levenshtein.html" class="function" rel="rdfs-seeAlso">levenshtein()</a> - Calculate Levenshtein distance between two strings</span></li>
<li class="member"> <span class="function"><a href="function.metaphone.html" class="function" rel="rdfs-seeAlso">metaphone()</a> - Calculate the metaphone key of a string</span></li>
<li class="member"> <span class="function"><a href="function.similar-text.html" class="function" rel="rdfs-seeAlso">similar_text()</a> - Calculate the similarity between two strings</span></li>
</ul>
</p>
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