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<refentry xml:id="function.usleep" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>usleep</refname>
  <refpurpose>Delay execution in microseconds</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>void</type><methodname>usleep</methodname>
   <methodparam><type>int</type><parameter>microseconds</parameter></methodparam>
  </methodsynopsis>
  <para>
   Delays program execution for the given number of microseconds.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>microseconds</parameter></term>
     <listitem>
      <para>
       Halt time in microseconds. A microsecond is one millionth of a
       second.
      </para>
      <note>
       <simpara>
        Values larger than <literal>1000000</literal> (i.e. sleeping for more than a second)
        may not be supported by the operating system. Use <function>sleep</function> instead.
       </simpara>
      </note>
      <note>
       <simpara>
        The sleep may be lengthened slightly (i.e. may be longer than <parameter>microseconds</parameter>)
        by any system activity or by the time spent processing the call or by the granularity of system timers.
       </simpara>
      </note>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.void;
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>usleep</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php

// Current time
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

// wait for 2 milliseconds
usleep(2000);

// back!
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

// wait for 30 milliseconds
usleep(30000);

// back again!
echo (new DateTime('now'))->format('H:i:s.v'), "\n";

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
11:13:28.005
11:13:28.007
11:13:28.037
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>sleep</function></member>
    <member><function>time_nanosleep</function></member>
    <member><function>time_sleep_until</function></member>
    <member><function>set_time_limit</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>
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