php-doc-en/reference/datetime/functions/microtime.xml

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<refentry xml:id="function.microtime" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>microtime</refname>
  <refpurpose>Return current Unix timestamp with microseconds</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>microtime</methodname>
   <methodparam choice="opt"><type>bool</type><parameter>get_as_float</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>microtime</function> returns the current Unix timestamp with
   microseconds. This function is only available on operating systems that
   support the gettimeofday() system call.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>get_as_float</parameter></term>
     <listitem>
      <para>
       When called without the optional argument, this function returns the string
       "msec sec" where sec is the current time measured in the number of
       seconds since the Unix Epoch (0:00:00 January 1, 1970 GMT), and
       msec is the microseconds part.
       Both portions of the string are returned in units of seconds.
      </para>
      <para>
       If the optional <parameter>get_as_float</parameter> is set to
       &true; then a <type>float</type> (in seconds) is returned.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.0.0</entry>
       <entry>
        The <parameter>get_as_float</parameter> parameter was added.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Timing script execution with <function>microtime</function></title>
    <programlisting role="php">
<![CDATA[
<?php
/**
 * Simple function to replicate PHP 5 behaviour
 */
function microtime_float()
{
    list($usec, $sec) = explode(" ", microtime());
    return ((float)$usec + (float)$sec);
}

$time_start = microtime_float();

// Sleep for a while
usleep(100);

$time_end = microtime_float();
$time = $time_end - $time_start;

echo "Did nothing in $time seconds\n";
?>
]]>
    </programlisting>
   </example>
   <example>
    <title>Timing script execution in PHP 5</title>
    <programlisting role="php">
<![CDATA[
<?php
$time_start = microtime(true);

// Sleep for a while
usleep(100);

$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Did nothing in $time seconds\n";
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

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

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