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b0d8103513
git-svn-id: https://svn.php.net/repository/phpdoc/es/trunk@349853 c90b9560-bf6c-de11-be94-00142212c4b1
131 lines
3.2 KiB
XML
131 lines
3.2 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<!-- EN-Revision: 8272e36f6a8e57e4ff19929ef39327e122d36a78 Maintainer: andresdzphp Status: ready -->
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<!-- Reviewed: no Maintainer: andresdzphp -->
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<refentry xml:id="function.array-key-first" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>array_key_first</refname>
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<refpurpose>Obtiene la primera clave de un array</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>mixed</type><methodname>array_key_first</methodname>
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<methodparam><type>array</type><parameter>array</parameter></methodparam>
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</methodsynopsis>
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<para>
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Consigue la primera clave del <parameter>array</parameter> dado sin afectar
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el puntero de array interno.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<variablelist>
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<varlistentry>
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<term><parameter>array</parameter></term>
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<listitem>
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<para>
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Un array;
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Devuelve la primera clave del <parameter>array</parameter> si el array no está vacío;
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&null; en caso contrario.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example xml:id="array_key_first.example.basic">
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<title>Uso básico de <function>array_key_first</function></title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$array = ['a' => 1, 'b' => 2, 'c' => 3];
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$firstKey = array_key_first($array);
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var_dump($firstKey);
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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string(1) "a"
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]]>
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</screen>
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</example>
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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<tip>
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<simpara>
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Hay varias maneras de proporcionar esta funcionalidad para las versiones anteriores a PHP 7.3.0.
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Es posible utilizar <function>array_keys</function>, pero eso puede ser más bien
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ineficiente. También es posible utilizar <function>reset</function> y <function>key</function>,
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pero eso puede cambiar el puntero del array interno. Una solución eficiente, que no hace
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cambio del puntero del array interno, escrito como polietileno:
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</simpara>
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<informalexample>
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<programlisting role="php">
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<![CDATA[
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<?php
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if (!function_exists('array_key_first')) {
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function array_key_first(array $arr) {
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foreach($arr as $key => $unused) {
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return $key;
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}
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return NULL;
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}
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}
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?>
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]]>
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</programlisting>
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</informalexample>
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</tip>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<simplelist>
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<member><function>array_key_last</function></member>
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<member><function>reset</function></member>
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</simplelist>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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