doc-en/reference/math/functions/clamp.xml at 1b1ac7b4e0b92f7affdf0394ce02c28de65e8f67 · php/doc-en · GitHub

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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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