<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="intlcalendar.fielddifference" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>IntlCalendar::fieldDifference</refname>
  <refpurpose>Calculate difference between given time and this objectʼs time</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>
   &style.oop;
  </para>
  <methodsynopsis role="IntlCalendar">
   <modifier>public</modifier> <type class="union"><type>int</type><type>false</type></type><methodname>IntlCalendar::fieldDifference</methodname>
   <methodparam><type>float</type><parameter>timestamp</parameter></methodparam>
   <methodparam><type>int</type><parameter>field</parameter></methodparam>
  </methodsynopsis>
  <para>
   &style.procedural;
  </para>
  <methodsynopsis>
   <type class="union"><type>int</type><type>false</type></type><methodname>intlcal_field_difference</methodname>
   <methodparam><type>IntlCalendar</type><parameter>calendar</parameter></methodparam>
   <methodparam><type>float</type><parameter>timestamp</parameter></methodparam>
   <methodparam><type>int</type><parameter>field</parameter></methodparam>
  </methodsynopsis>
  <para>
   Return the difference between the given time and the time this object is
   set to, with respect to the quantity specified the
   <parameter>field</parameter> parameter.
  </para>
  <para>
   This method is meant to be called successively, first with the most
   significant field of interest down to the least significant field. To this
   end, as a side effect, this calendarʼs value for the field specified is
   advanced by the amount returned.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>calendar</parameter></term>
    <listitem>
     &intl.parameter.intl-calendar;
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>timestamp</parameter></term>
    <listitem>
     <para>
      The time against which to compare the quantity represented by the
      <parameter>field</parameter>. For the result to be positive, the time
      given for this parameter must be ahead of the time of the object the
      method is being invoked on.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>field</parameter></term>
    <listitem>
     <para>
      The field that represents the quantity being compared.
     </para>
     &reference.intl.incfieldparam;
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a (signed) difference of time in the unit associated with the
   specified field&return.falseforfailure;.
  </para>
 </refsect1>


 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
   <title><function>IntlCalendar::fieldDifference</function></title>
    <programlisting role="php">
<![CDATA[
<?php
ini_set('date.timezone', 'Europe/Lisbon');
ini_set('intl.default_locale', 'fr_FR');

$cal1 = IntlCalendar::fromDateTime('2012-02-29 09:00:11');
$cal2 = IntlCalendar::fromDateTime('2013-03-01 09:19:29');
$time = $cal2->getTime();

echo "Time before: ", IntlDateFormatter::formatObject($cal1), "\n";

printf(
    "The difference in time is %d year(s), %d month(s), "
  . "%d day(s), %d hour(s) and %d minute(s)\n",
    $cal1->fieldDifference($time, IntlCalendar::FIELD_YEAR),
    $cal1->fieldDifference($time, IntlCalendar::FIELD_MONTH),
    $cal1->fieldDifference($time, IntlCalendar::FIELD_DAY_OF_MONTH),
    $cal1->fieldDifference($time, IntlCalendar::FIELD_HOUR_OF_DAY),
    $cal1->fieldDifference($time, IntlCalendar::FIELD_MINUTE)
);

//now it was advanced to the target time, exception for the seconds,
//for which we did not measure the difference
echo "Time after: ", IntlDateFormatter::formatObject($cal1), "\n";
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Time before: 29 févr. 2012 09:00:11
The difference in time is 1 year(s), 0 month(s), 1 day(s), 0 hour(s) and 19 minute(s)
Time after: 1 mars 2013 09:19:11
]]>
    </screen>
   </example>
  </para>
 </refsect1>

</refentry>
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