php-doc-en/reference/datetime/functions/strtotime.xml
2010-02-18 14:25:56 +00:00

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<?xml version="1.0" encoding="iso-8859-1"?>
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<refentry xml:id="function.strtotime" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>strtotime</refname>
<refpurpose>Parse about any English textual datetime description into a Unix timestamp</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>int</type><methodname>strtotime</methodname>
<methodparam><type>string</type><parameter>time</parameter></methodparam>
<methodparam choice="opt"><type>int</type><parameter>now</parameter></methodparam>
</methodsynopsis>
<simpara>
The function expects to be given a string containing a US English date
format and will try to parse that format into a Unix timestamp (the
number of seconds since January 1 1970 00:00:00 UTC), relative
to the timestamp given in <parameter>now</parameter>, or the current time
if <parameter>now</parameter> is not supplied.
</simpara>
<para>
This function will use the <envar>TZ</envar> environment variable (if
available) to calculate the timestamp. Since PHP 5.1.0 there are easier
ways to define the timezone that is used across all date/time functions.
That process is explained in the
<function>date_default_timezone_get</function> function page.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>time</parameter></term>
<listitem>
<para>
The string to parse. Before PHP 5.0.0, microseconds weren't allowed in
the time, since PHP 5.0.0 they are allowed but ignored.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>now</parameter></term>
<listitem>
<para>
The timestamp which is used as a base for the calculation of relative
dates.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns a timestamp on success, &false; otherwise. Previous to PHP 5.1.0,
this function would return <literal>-1</literal> on failure.
</para>
</refsect1>
<refsect1 role="errors">
&reftitle.errors;
&date.timezone.errors.description;
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>5.3.0</entry>
<entry>
Prior to PHP 5.3.0, <literal>24:00</literal> was not a valid format and
<function>strtotime</function> returned &false;. From 5.3.0 this is
equivalent to <literal>0:00</literal>.
</entry>
</row>
<row>
<entry>5.2.7</entry>
<entry>
In PHP 5 prior to 5.2.7, requesting a given occurrence of a
given weekday in a month where that weekday was the first day
of the month would incorrectly add one week to the returned
timestamp. This has been corrected in 5.2.7 and later
versions.
</entry>
</row>
<row>
<entry>5.1.0</entry>
<entry>
Now returns &false; on failure, instead
of <literal>-1</literal>.
</entry>
</row>
&date.timezone.errors.changelog;
<row>
<entry>5.0.2</entry>
<entry>
In PHP 5 up to 5.0.2, <literal>"now"</literal> and other
relative times are wrongly computed from today's
midnight. This differs from other versions where it is
correctly computed from current time.
</entry>
</row>
<row>
<entry>4.4.0</entry>
<entry>
In PHP versions prior to 4.4.0, <literal>"next"</literal> is incorrectly
computed as +2. A typical solution to this is to use
<literal>"+1"</literal>.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>A <function>strtotime</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
echo strtotime("now"), "\n";
echo strtotime("10 September 2000"), "\n";
echo strtotime("+1 day"), "\n";
echo strtotime("+1 week"), "\n";
echo strtotime("+1 week 2 days 4 hours 2 seconds"), "\n";
echo strtotime("next Thursday"), "\n";
echo strtotime("last Monday"), "\n";
?>
]]>
</programlisting>
</example>
</para>
<para>
<example>
<title>Checking for failure</title>
<programlisting role="php">
<![CDATA[
<?php
$str = 'Not Good';
// previous to PHP 5.1.0 you would compare with -1, instead of false
if (($timestamp = strtotime($str)) === false) {
echo "The string ($str) is bogus";
} else {
echo "$str == " . date('l dS \o\f F Y h:i:s A', $timestamp);
}
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="notes">
&reftitle.notes;
<note>
<para>
If the number of the year is specified in a two digit format, the values
between 00-69 are mapped to 2000-2069 and 70-99 to 1970-1999. See the notes
below for possible differences on 32bit systems (possible dates might end on
2038-01-19 03:14:07).
</para>
</note>
<note>
<para>
The valid range of a timestamp is typically from Fri, 13 Dec
1901 20:45:54 UTC to Tue, 19 Jan 2038 03:14:07 UTC. (These are
the dates that correspond to the minimum and maximum values for
a 32-bit signed integer.)
Additionally, not all platforms support negative timestamps, therefore
your date range may be limited to no earlier than the Unix epoch. This
means that e.g. dates prior to Jan 1, 1970 will not work on Windows,
some Linux distributions, and a few other operating systems. PHP 5.1.0 and
newer versions overcome this limitation though.
</para>
</note>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>strptime</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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