is-numeric.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Author$ -->
<!-- EN-Revision: 0817d5b2835f8a47314823338d983fa2c5005dfc Maintainer: nio Status: ready -->
<!-- CREDITS: Luffy -->
<refentry xml:id="function.is-numeric" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>is_numeric</refname>
  <refpurpose>
   检测变量是否是数字或数字字符串
  </refpurpose>
 </refnamediv>

  <refsect1 role="description">
    &reftitle.description;
    <methodsynopsis>
     <type>bool</type><methodname>is_numeric</methodname>
     <methodparam><type>mixed</type><parameter>value</parameter></methodparam>
    </methodsynopsis>
    <para>
     检测变量是否是数字或<link linkend="language.types.numeric-strings">数字字符串</link>。
    </para>
  </refsect1>

  <refsect1 role="parameters">
   &reftitle.parameters;
   <para>
    <variablelist>
     <varlistentry>
      <term><parameter>value</parameter></term>
      <listitem>
       <para>
        需要检测的变量。
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
   </para>
  </refsect1>

  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
    如果 <parameter>value</parameter> 是数字或<link linkend="language.types.numeric-strings">数字字符串</link>，
    返回 &true;，否则返回 &false;。
   </para>
  </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>8.0.0</entry>
      <entry>
       以空格结尾的数字字符串（<literal>"42 "</literal>）现在将返回 &true;。以前，会返回 &false;。
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>is_numeric</function> 示例</title>
    <programlisting role="php">
     <![CDATA[
<?php
$tests = array(
    "42",
    1337,
    0x539,
    02471,
    0b10100111001,
    1337e0,
    "0x539",
    "02471",
    "0b10100111001",
    "1337e0",
    "not numeric",
    array(),
    9.1,
    null,
    '',
);

foreach ($tests as $element) {
    if (is_numeric($element)) {
        echo var_export($element, true) . " is numeric", PHP_EOL;
    } else {
        echo var_export($element, true) . " is NOT numeric", PHP_EOL;
    }
}
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
     <![CDATA[
'42' is numeric
1337 is numeric
1337 is numeric
1337 is numeric
1337 is numeric
1337.0 is numeric
'0x539' is NOT numeric
'02471' is numeric
'0b10100111001' is NOT numeric
'1337e0' is numeric
'not numeric' is NOT numeric
array (
) is NOT numeric
9.1 is numeric
NULL is NOT numeric
'' is NOT numeric
]]>
    </screen>
   </example>
  </para>

  <para>
   <example>
    <title>带有空格的 <function>is_numeric</function></title>
    <programlisting role="php">
     <![CDATA[
<?php
$tests = [
    " 42",
    "42 ",
    "\u{A0}9001", // non-breaking space
    "9001\u{A0}", // non-breaking space
];
foreach ($tests as $element) {
    if (is_numeric($element)) {
        echo var_export($element, true) . " is numeric", PHP_EOL;
    } else {
        echo var_export($element, true) . " is NOT numeric", PHP_EOL;
    }
}
?>
]]>
    </programlisting>
    &example.outputs.8;
    <screen>
     <![CDATA[
' 42' is numeric
'42 ' is numeric
' 9001' is NOT numeric
'9001 ' is NOT numeric
]]>
    </screen>
    &example.outputs.7;
    <screen>
     <![CDATA[
' 42' is numeric
'42 ' is NOT numeric
' 9001' is NOT numeric
'9001 ' is NOT numeric
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><link linkend="language.types.numeric-strings">数字字符串</link></member>
    <member><function>ctype_digit</function></member>
    <member><function>is_bool</function></member>
    <member><function>is_null</function></member>
    <member><function>is_float</function></member>
    <member><function>is_int</function></member>
    <member><function>is_string</function></member>
    <member><function>is_object</function></member>
    <member><function>is_array</function></member>
    <member><function>filter_var</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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