ltrim.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- EN-Revision: 27ae0a4a16cdfc868a884c0f0dad7023b5f2709c Maintainer: daijie Status: ready -->
<!-- CREDITS: mowangjuanzi -->
<refentry xml:id="function.ltrim" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>ltrim</refname>
  <refpurpose>删除字符串开头的空白字符（或其他字符）</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>ltrim</methodname>
   <methodparam><type>string</type><parameter>string</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>characters</parameter><initializer>" \n\r\t\v\x00"</initializer></methodparam>
  </methodsynopsis>
  <simpara>
   去除字符串开头的空白字符（或其他字符）
  </simpara>
  <simpara>
   不带第二个参数，<function>mb_ltrim</function> 将去除下列字符：
  </simpara>
  &strings.stripped.characters;
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>string</parameter></term>
    <listitem>
     <simpara>
      输入字符串。
     </simpara>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>characters</parameter></term>
    <listitem>
     &strings.parameter.characters.optional;
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <simpara>
   该函数返回从 <parameter>string</parameter> 开头去除了空白字符的字符串。
  </simpara>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>ltrim</function> 使用示例</title>
    <programlisting role="php">
<![CDATA[
<?php

$text = "\t\tThese are a few words :) ...  ";
$binary = "\x09Example string\x0A";
$hello  = "Hello World";
var_dump($text, $binary, $hello);

print "\n";


$trimmed = ltrim($text);
var_dump($trimmed);

$trimmed = ltrim($text, " \t.");
var_dump($trimmed);

$trimmed = ltrim($hello, "Hdle");
var_dump($trimmed);

// 删除 $binary 开头的 ASCII 控制字符
// (从 0 到 31，包括 0 和 31)
$clean = ltrim($binary, "\x00..\x1F");
var_dump($clean);

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
string(32) "        These are a few words :) ...  "
string(16) "    Example string
"
string(11) "Hello World"

string(30) "These are a few words :) ...  "
string(30) "These are a few words :) ...  "
string(7) "o World"
string(15) "Example string
"
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>trim</function></member>
   <member><function>rtrim</function></member>
  </simplelist>
 </refsect1>

</refentry>
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