diff.xml

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<refentry xml:id="datetime.diff" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>DateTimeInterface::diff</refname>
  <refname>DateTimeImmutable::diff</refname>
  <refname>DateTime::diff</refname>
  <refname>date_diff</refname>
  <refpurpose>返回两个 DateTime 之间的差值</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <para>&style.oop;</para>
  <methodsynopsis role="DateTimeInterface">
   <modifier>public</modifier> <type>DateInterval</type><methodname>DateTimeInterface::diff</methodname>
   <methodparam><type>DateTimeInterface</type><parameter>targetObject</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>absolute</parameter><initializer>&false;</initializer></methodparam>
  </methodsynopsis>
  <methodsynopsis role="DateTimeImmutable">
   <modifier>public</modifier> <type>DateInterval</type><methodname>DateTimeImmutable::diff</methodname>
   <methodparam><type>DateTimeInterface</type><parameter>targetObject</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>absolute</parameter><initializer>&false;</initializer></methodparam>
  </methodsynopsis>
  <methodsynopsis role="DateTime">
   <modifier>public</modifier> <type>DateInterval</type><methodname>DateTime::diff</methodname>
   <methodparam><type>DateTimeInterface</type><parameter>targetObject</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>absolute</parameter><initializer>&false;</initializer></methodparam>
  </methodsynopsis>
  <para>&style.procedural;</para>
  <methodsynopsis>
   <type>DateInterval</type><methodname>date_diff</methodname>
   <methodparam><type>DateTimeInterface</type><parameter>baseObject</parameter></methodparam>
   <methodparam><type>DateTimeInterface</type><parameter>targetObject</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>absolute</parameter><initializer>&false;</initializer></methodparam>
  </methodsynopsis>
  <para>
   返回两个 <classname>DateTimeInterface</classname> 对象的差值。
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>datetime</parameter></term>
    <listitem>
     <para>
      要比较的日期。
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>absolute</parameter></term>
    <listitem>
     <para>
      间隔是否强制为正的？
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   <classname>DateInterval</classname> 对象表示两个日期之间的差值。
  </para>
  <para>
   <parameter>absolute</parameter> 参数只影响 <classname>DateInterval</classname> 对象的
   <parameter>invert</parameter> 属性。
  </para>
  <para>
   返回更具体的表示应用于原始对象（<parameter>$this</parameter> 或
   <parameter>$originObject</parameter>）到达 <parameter>$targetObject</parameter>
   的时钟时间间隔的值。该过程始终不可逆。
  </para>
  <para>
   该方法知道 DST 转换，因此可以根据示例返回 <literal>24 小时 30
   分钟</literal>的时间间隔。如果想使用绝对时间计算，则需要先将
   <parameter>$this</parameter>/<parameter>$baseObject</parameter> 和
   <parameter>$targetObject</parameter> 都转换为 UTC。
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title><function>DateTimeImmutable::diff</function> 示例</title>
   <para>&style.oop;</para>
   <programlisting role="php">
<![CDATA[
<?php
$origin = new DateTimeImmutable('2009-10-11');
$target = new DateTimeImmutable('2009-10-13');
$interval = $origin->diff($target);
echo $interval->format('%R%a days');
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
+2 days
]]>
   </screen>
   <para>&style.procedural;</para>
   <programlisting role="php">
<![CDATA[
<?php
$origin = date_create('2009-10-11');
$target = date_create('2009-10-13');
$interval = date_diff($origin, $target);
echo $interval->format('%R%a days');
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
+2 days
]]>
   </screen>
  </example>

  <example>
   <title>DST 转换期间的 <methodname>DateTimeInterface::diff</methodname></title>
   <programlisting role="php">
<![CDATA[
<?php
$originalTime = new DateTimeImmutable("2021-10-30 09:00:00 Europe/London");
$targetTime = new DateTimeImmutable("2021-10-31 08:30:00 Europe/London");
$interval = $originalTime->diff($targetTime);
echo $interval->format("%H:%I:%S (Full days: %a)"), "\n";
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
24:30:00 (Full days: 0)
]]>
   </screen>
  </example>

  <example>
   <title><methodname>DateTimeInterface::diff</methodname> range</title>
   <para>
    该方法返回的值是从 <parameter>$this</parameter> 到达 <parameter>$targetObject</parameter> 
    所需要的精确时间。因此，将 1 月 1 日与 12 月 31 日进行比较，返回的结果是 364，而不是
    365 天（对于非闰年）。
   </para>
   <programlisting role="php">
    <![CDATA[
<?php
$originalTime = new DateTimeImmutable("2023-01-01 UTC");
$targetTime = new DateTimeImmutable("2023-12-31 UTC");
$interval = $originalTime->diff($targetTime);
echo "Full days: ", $interval->format("%a"), "\n";
]]>
   </programlisting>
   &example.outputs;
   <screen>
    <![CDATA[
Full days: 364
]]>
   </screen>
  </example>

  <example>
   <title><classname>DateTime</classname> 对象比较</title>
   <note>
    <para>
     <classname>DateTimeImmutable</classname> 和 <classname>DateTime</classname>
     对象可以使用<link linkend="language.operators.comparison">比较运算符</link>进行比较。
    </para>
   </note>
   <programlisting role="php">
<![CDATA[
<?php
$date1 = new DateTime("now");
$date2 = new DateTime("tomorrow");

var_dump($date1 == $date2);
var_dump($date1 < $date2);
var_dump($date1 > $date2);
]]>
  </programlisting>
  &example.outputs;
  <screen>
<![CDATA[
bool(false)
bool(true)
bool(false)
]]>
  </screen>
  </example>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>DateInterval::format</function></member>
   <member><function>DateTime::add</function></member>
   <member><function>DateTime::sub</function></member>
  </simplelist>
 </refsect1>

</refentry>
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