<!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>Binary to decimal</title>
</head>
<body><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="function.base-convert.html">base_convert</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.ceil.html">ceil</a></div>
<div class="up"><a href="ref.math.html">Math Functions</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="function.bindec" class="refentry">
<div class="refnamediv">
<h1 class="refname">bindec</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">bindec</span> — <span class="dc-title">Binary to decimal</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.bindec-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type"><a href="language.pseudo-types.html#language.types.number" class="type number">number</a></span> <span class="methodname"><strong>bindec</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$binary_string</code></span>
)</div>
<p class="para rdfs-comment">
Returns the decimal equivalent of the binary number represented by
the <em><code class="parameter">binary_string</code></em> argument.
</p>
<p class="para">
<span class="function"><strong>bindec()</strong></span> converts a binary number to an
<span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> or, if needed for size reasons, <span class="type"><a href="language.types.float.html" class="type float">float</a></span>.
</p>
<p class="para">
<span class="function"><strong>bindec()</strong></span> interprets all
<em><code class="parameter">binary_string</code></em> values as unsigned
integers. This is because <span class="function"><strong>bindec()</strong></span> sees
the most significant bit as another order of magnitude
rather than as the sign bit.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.bindec-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">binary_string</code></em></span>
<dd>
<p class="para">
The binary string to convert
</p>
</dd>
</dt>
</dl>
</p>
<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
The parameter must be a string.
Using other data types will produce unexpected results.
</p>
</div>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.bindec-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
The decimal value of <em><code class="parameter">binary_string</code></em>
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.bindec-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>4.1.0</td>
<td>
The function can now convert numbers that are too large to
fit into the platforms <span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> type, larger values
are returned as <span class="type"><a href="language.types.float.html" class="type float">float</a></span> in that case.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.bindec-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3449">
<p><strong>Example #1 <span class="function"><strong>bindec()</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: #007700">echo </span><span style="color: #0000BB">bindec</span><span style="color: #007700">(</span><span style="color: #DD0000">'110011'</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />echo </span><span style="color: #0000BB">bindec</span><span style="color: #007700">(</span><span style="color: #DD0000">'000110011'</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br />echo </span><span style="color: #0000BB">bindec</span><span style="color: #007700">(</span><span style="color: #DD0000">'111'</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>
51
51
7
</pre></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-3450">
<p><strong>Example #2 <span class="function"><strong>bindec()</strong></span> interprets input as unsigned integers</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">/*<br /> * The lesson from this example is in the output<br /> * rather than the PHP code itself.<br /> */<br /><br /></span><span style="color: #0000BB">$magnitude_lower </span><span style="color: #007700">= </span><span style="color: #0000BB">pow</span><span style="color: #007700">(</span><span style="color: #0000BB">2</span><span style="color: #007700">, (</span><span style="color: #0000BB">PHP_INT_SIZE </span><span style="color: #007700">* </span><span style="color: #0000BB">8</span><span style="color: #007700">) - </span><span style="color: #0000BB">2</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">p</span><span style="color: #007700">(</span><span style="color: #0000BB">$magnitude_lower </span><span style="color: #007700">- </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">p</span><span style="color: #007700">(</span><span style="color: #0000BB">$magnitude_lower</span><span style="color: #007700">, </span><span style="color: #DD0000">'See the rollover? Watch it next time around...'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">p</span><span style="color: #007700">(</span><span style="color: #0000BB">PHP_INT_MAX</span><span style="color: #007700">, </span><span style="color: #DD0000">'PHP_INT_MAX'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">p</span><span style="color: #007700">(~</span><span style="color: #0000BB">PHP_INT_MAX</span><span style="color: #007700">, </span><span style="color: #DD0000">'interpreted to be one more than PHP_INT_MAX'</span><span style="color: #007700">);<br /><br />if (</span><span style="color: #0000BB">PHP_INT_SIZE </span><span style="color: #007700">== </span><span style="color: #0000BB">4</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$note </span><span style="color: #007700">= </span><span style="color: #DD0000">'interpreted to be the largest unsigned integer'</span><span style="color: #007700">;<br />} else {<br /> </span><span style="color: #0000BB">$note </span><span style="color: #007700">= </span><span style="color: #DD0000">'interpreted to be the largest unsigned integer<br /> (18446744073709551615) but skewed by float precision'</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">p</span><span style="color: #007700">(-</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">$note</span><span style="color: #007700">);<br /><br /><br />function </span><span style="color: #0000BB">p</span><span style="color: #007700">(</span><span style="color: #0000BB">$input</span><span style="color: #007700">, </span><span style="color: #0000BB">$note </span><span style="color: #007700">= </span><span style="color: #DD0000">''</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"input: </span><span style="color: #0000BB">$input</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$format </span><span style="color: #007700">= </span><span style="color: #DD0000">'%0' </span><span style="color: #007700">. (</span><span style="color: #0000BB">PHP_INT_SIZE </span><span style="color: #007700">* </span><span style="color: #0000BB">8</span><span style="color: #007700">) . </span><span style="color: #DD0000">'b'</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$bin </span><span style="color: #007700">= </span><span style="color: #0000BB">sprintf</span><span style="color: #007700">(</span><span style="color: #0000BB">$format</span><span style="color: #007700">, </span><span style="color: #0000BB">$input</span><span style="color: #007700">);<br /> echo </span><span style="color: #DD0000">"binary: </span><span style="color: #0000BB">$bin</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">ini_set</span><span style="color: #007700">(</span><span style="color: #DD0000">'precision'</span><span style="color: #007700">, </span><span style="color: #0000BB">20</span><span style="color: #007700">); </span><span style="color: #FF8000">// For readability on 64 bit boxes.<br /> </span><span style="color: #0000BB">$dec </span><span style="color: #007700">= </span><span style="color: #0000BB">bindec</span><span style="color: #007700">(</span><span style="color: #0000BB">$bin</span><span style="color: #007700">);<br /> echo </span><span style="color: #DD0000">'bindec(): ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$dec </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /> if (</span><span style="color: #0000BB">$note</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"NOTE: </span><span style="color: #0000BB">$note</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /> }<br /><br /> echo </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>Output of the above example on 32 bit machines:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
input: 1073741823
binary: 00111111111111111111111111111111
bindec(): 1073741823
input: 1073741824
binary: 01000000000000000000000000000000
bindec(): 1073741824
NOTE: See the rollover? Watch it next time around...
input: 2147483647
binary: 01111111111111111111111111111111
bindec(): 2147483647
NOTE: PHP_INT_MAX
input: -2147483648
binary: 10000000000000000000000000000000
bindec(): 2147483648
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 11111111111111111111111111111111
bindec(): 4294967295
NOTE: interpreted to be the largest unsigned integer
</pre></div>
</div>
<div class="example-contents"><p>Output of the above example on 64 bit machines:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
input: 4611686018427387903
binary: 0011111111111111111111111111111111111111111111111111111111111111
bindec(): 4611686018427387903
input: 4611686018427387904
binary: 0100000000000000000000000000000000000000000000000000000000000000
bindec(): 4611686018427387904
NOTE: See the rollover? Watch it next time around...
input: 9223372036854775807
binary: 0111111111111111111111111111111111111111111111111111111111111111
bindec(): 9223372036854775807
NOTE: PHP_INT_MAX
input: -9223372036854775808
binary: 1000000000000000000000000000000000000000000000000000000000000000
bindec(): 9223372036854775808
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 1111111111111111111111111111111111111111111111111111111111111111
bindec(): 18446744073709551616
NOTE: interpreted to be the largest unsigned integer
(18446744073709551615) but skewed by float precision
</pre></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.bindec-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.decbin.html" class="function" rel="rdfs-seeAlso">decbin()</a> - Decimal to binary</span></li>
<li class="member"> <span class="function"><a href="function.octdec.html" class="function" rel="rdfs-seeAlso">octdec()</a> - Octal to decimal</span></li>
<li class="member"> <span class="function"><a href="function.hexdec.html" class="function" rel="rdfs-seeAlso">hexdec()</a> - Hexadecimal to decimal</span></li>
<li class="member"> <span class="function"><a href="function.base-convert.html" class="function" rel="rdfs-seeAlso">base_convert()</a> - Convert a number between arbitrary bases</span></li>
</ul>
</p>
</div>
</div><hr /><div class="manualnavbar" style="text-align: center;">
<div class="prev" style="text-align: left; float: left;"><a href="function.base-convert.html">base_convert</a></div>
<div class="next" style="text-align: right; float: right;"><a href="function.ceil.html">ceil</a></div>
<div class="up"><a href="ref.math.html">Math Functions</a></div>
<div class="home"><a href="index.html">PHP Manual</a></div>
</div></body></html>
