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Document clamp function #4814

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34 changes: 34 additions & 0 deletions appendices/migration85/new-functions.xml
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<?xml version="1.0" encoding="utf-8"?>
<sect1 xml:id="migration85.new-functions">
<title>New Functions</title>

<sect2 xml:id="migration85.new-functions.core">
<title>Core</title>

<simplelist>
<!-- RFC: https://wiki.php.net/rfc/clamp -->
<member><function>clamp</function></member>
</simplelist>
</sect2>

</sect1>
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1 change: 1 addition & 0 deletions reference/array/versions.xml
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Expand Up @@ -64,6 +64,7 @@
<function name='array_walk_recursive' from='PHP 5, PHP 7, PHP 8'/>
<function name='arsort' from='PHP 4, PHP 5, PHP 7, PHP 8'/>
<function name='asort' from='PHP 4, PHP 5, PHP 7, PHP 8'/>
<function name='clamp' from='PHP 8 &gt;= 8.5.0'/>
<function name='compact' from='PHP 4, PHP 5, PHP 7, PHP 8'/>
<function name='count' from='PHP 4, PHP 5, PHP 7, PHP 8'/>
<function name='current' from='PHP 4, PHP 5, PHP 7, PHP 8'/>
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151 changes: 151 additions & 0 deletions reference/math/functions/clamp.xml
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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.clamp" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>clamp</refname>
<refpurpose>Return the given value if in range, else return the nearest bound</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>mixed</type><methodname>clamp</methodname>
<methodparam><type>mixed</type><parameter>value</parameter></methodparam>
<methodparam><type>mixed</type><parameter>min</parameter></methodparam>
<methodparam><type>mixed</type><parameter>max</parameter></methodparam>
</methodsynopsis>
<para>
Return the given value if in range of <parameter>min</parameter> and <parameter>max</parameter>.
Else if it's lower than <parameter>min</parameter>, return <parameter>min</parameter>.
Else return <parameter>max</parameter>.
</para>
<note>
<para>
Values of different types will be compared using the <link linkend="language.operators.comparison">
standard comparison rules</link>. For instance, a non-numeric <type>string</type> will be
compared to an <type>int</type> as though it were <literal>0</literal>, but multiple non-numeric
<type>string</type> values will be compared alphanumerically. The actual value returned will be of the
original type with no conversion applied.
</para>
</note>
<caution>
<simpara>
Be careful when passing arguments of different types because
<function>clamp</function> can produce unpredictable results.
</simpara>
</caution>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>value</parameter></term>
<listitem>
<para>
Any <link linkend="language.operators.comparison">comparable</link>
value to be clamped between <parameter>min</parameter> and <parameter>max</parameter>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>min</parameter></term>
<listitem>
<para>
A <link linkend="language.operators.comparison">comparable</link> minimum to limit
the <parameter>value</parameter> to.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>max</parameter></term>
<listitem>
<para>
A <link linkend="language.operators.comparison">comparable</link> maximum to limit
the <parameter>value</parameter> to.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
<function>clamp</function> returns the parameter <parameter>value</parameter> if
considered "between" <parameter>min</parameter> and <parameter>max</parameter> according to standard
comparisons.
</para>
<para>
If <parameter>value</parameter> is <constant>NAN</constant>, then the returned value will also be
<constant>NAN</constant>.
</para>
</refsect1>

<refsect1 role="errors">
&reftitle.errors;
<para>
If <parameter>min</parameter> is greater than <parameter>max</parameter>,
<function>clamp</function> throws a <classname>ValueError</classname>.
</para>
<para>
If <parameter>min</parameter> or <parameter>max</parameter> is <constant>NAN</constant>,
<function>clamp</function> throws a <classname>ValueError</classname>.
</para>
</refsect1>

<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Example uses of <function>clamp</function></title>
<programlisting role="php">
<![CDATA[
<?php
echo clamp(-5, min: 0, max: 100), PHP_EOL; // 0
echo clamp(55, min: 0, max: 100), PHP_EOL; // 55
echo clamp(103, min: 0, max: 100), PHP_EOL; // 100

echo clamp("J", min: "A", max: "F"), PHP_EOL; // "F"

clamp(
new \DateTimeImmutable('2025-08-01'),
min: new \DateTimeImmutable('2025-08-15'),
max: new \DateTimeImmutable('2025-09-15'),
)->format('Y-m-d'), PHP_EOL; // 2025-08-15
?>
]]>
</programlisting>
</example>
</para>

</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>min</function></member>
<member><function>max</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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