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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.bindec" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>bindec</refname>
<refpurpose>Binary to decimal</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type class="union"><type>int</type><type>float</type></type><methodname>bindec</methodname>
<methodparam><type>string</type><parameter>binary_string</parameter></methodparam>
</methodsynopsis>
<para>
Returns the decimal equivalent of the binary number represented by
the <parameter>binary_string</parameter> argument.
</para>
<para>
<function>bindec</function> converts a binary number to an
<type>int</type> or, if needed for size reasons, <type>float</type>.
</para>
<para>
<function>bindec</function> interprets all
<parameter>binary_string</parameter> values as unsigned
integers. This is because <function>bindec</function> sees
the most significant bit as another order of magnitude
rather than as the sign bit.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>binary_string</parameter></term>
<listitem>
<para>
The binary string to convert.
Any invalid characters in <parameter>binary_string</parameter> are silently ignored.
As of PHP 7.4.0 supplying any invalid characters is deprecated.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<warning>
<para>
The parameter must be a string.
Using other data types will produce unexpected results.
</para>
</warning>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
The decimal value of <parameter>binary_string</parameter>
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>7.4.0</entry>
<entry>
Passing invalid characters will now generate a deprecation notice.
The result will still be computed as if the invalid characters did not exist.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>bindec</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
echo bindec('110011') . "\n";
echo bindec('000110011') . "\n";
echo bindec('111');
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
51
51
7
]]>
</screen>
</example>
</para>
<para>
<example>
<title><function>bindec</function> interprets input as unsigned integers</title>
<programlisting role="php">
<![CDATA[
<?php
/*
* The lesson from this example is in the output
* rather than the PHP code itself.
*/
$magnitude_lower = pow(2, (PHP_INT_SIZE * 8) - 2);
p($magnitude_lower - 1);
p($magnitude_lower, 'See the rollover? Watch it next time around...');
p(PHP_INT_MAX, 'PHP_INT_MAX');
p(~PHP_INT_MAX, 'interpreted to be one more than PHP_INT_MAX');
if (PHP_INT_SIZE == 4) {
$note = 'interpreted to be the largest unsigned integer';
} else {
$note = 'interpreted to be the largest unsigned integer
(18446744073709551615) but skewed by float precision';
}
p(-1, $note);
function p($input, $note = '') {
echo "input: $input\n";
$format = '%0' . (PHP_INT_SIZE * 8) . 'b';
$bin = sprintf($format, $input);
echo "binary: $bin\n";
ini_set('precision', 20); // For readability on 64 bit boxes.
$dec = bindec($bin);
echo 'bindec(): ' . $dec . "\n";
if ($note) {
echo "NOTE: $note\n";
}
echo "\n";
}
?>
]]>
</programlisting>
&example.outputs.32bit;
<screen>
<![CDATA[
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
]]>
</screen>
&example.outputs.64bit;
<screen>
<![CDATA[
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
]]>
</screen>
</example>
</para>
</refsect1>
<refsect1 role="notes">
&reftitle.notes;
<note>
<para>
The function can convert numbers that are too large to fit into the platforms
<type>int</type> type, larger values are returned as <type>float</type> in
that case.
</para>
</note>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>decbin</function></member>
<member><function>octdec</function></member>
<member><function>hexdec</function></member>
<member><function>base_convert</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
