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<title>Generate a single-byte string from a number</title>
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</div><hr /><div id="function.chr" class="refentry">
<div class="refnamediv">
<h1 class="refname">chr</h1>
<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">chr</span> — <span class="dc-title">Generate a single-byte string from a number</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.chr-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">string</span> <span class="methodname"><strong>chr</strong></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$bytevalue</code></span>
)</div>
<p class="para rdfs-comment">
Returns a one-character string containing the character specified
by interpreting <code class="parameter">bytevalue</code> as an unsigned integer.
</p>
<p class="para">
This can be used to create a one-character string in a single-byte encoding such as ASCII, ISO-8859, or Windows 1252, by passing the position of a desired character in the encoding's mapping table. However, note that this function is not aware of any string encoding, and in particular cannot be passed a Unicode code point value to generate a string in a multibyte encoding like UTF-8 or UTF-16.
</p>
<p class="para">
This function complements <span class="function"><a href="function.ord.html" class="function">ord()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.chr-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<code class="parameter">bytevalue</code></dt>
<dd>
<p class="para">
An integer between 0 and 255.
</p>
<p class="para">
Values outside the valid range (0..255) will be bitwise and'ed with 255,
which is equivalent to the following algorithm:
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
while ($bytevalue < 0) {<br /> $bytevalue += 256;<br />}<br />$bytevalue %= 256;</span>
</code></div>
</div>
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.chr-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
A single-character string containing the specified byte.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.chr-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-6020">
<p><strong>Example #1 <span class="function"><strong>chr()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Assumes the string will be used as ASCII or an ASCII-compatible encoding<br /><br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">= </span><span style="color: #DD0000">"The string ends in escape: "</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">.= </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">27</span><span style="color: #007700">); </span><span style="color: #FF8000">/* add an escape character at the end of $str */<br /><br />/* Often this is more useful */<br /><br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">= </span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #DD0000">"The string ends in escape: %c"</span><span style="color: #007700">, </span><span style="color: #0000BB">27</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<div class="example" id="example-6021">
<p><strong>Example #2 Overflow behavior</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">chr</span><span style="color: #007700">(-</span><span style="color: #0000BB">159</span><span style="color: #007700">), </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">833</span><span style="color: #007700">), </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<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 screen">
<div class="cdata"><pre>
aA
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-6022">
<p><strong>Example #3 Building a UTF-8 string from individual bytes</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">declare(</span><span style="color: #0000BB">encoding</span><span style="color: #007700">=</span><span style="color: #DD0000">'UTF-8'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$str </span><span style="color: #007700">= </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">240</span><span style="color: #007700">) . </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">159</span><span style="color: #007700">) . </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">144</span><span style="color: #007700">) . </span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">152</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$str</span><span style="color: #007700">;<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 screen"><br />
🐘<br />
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.chr-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><span class="function"><a href="function.sprintf.html" class="function" rel="rdfs-seeAlso">sprintf()</a> - Return a formatted string</span> with a format string of <em>%c</em></li>
<li class="member"><span class="function"><a href="function.ord.html" class="function">ord()</a></span></li>
<li class="member">An <a href="http://www.asciitable.com" class="link external">» ASCII-table</a></li>
</ul>
</p>
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