php-doc-en/reference/strings/functions/trim.xml

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  <refentry id="function.trim">
   <refnamediv>
    <refname>trim</refname> 
    <refpurpose>
     Strip whitespace (or other characters) from the beginning and end of a string
    </refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>string</type><methodname>trim</methodname>
      <methodparam><type>string</type><parameter>str</parameter></methodparam>
      <methodparam choice="opt"><type>string</type><parameter>charlist</parameter></methodparam>
     </methodsynopsis>
    <para>
     This function returns a string with whitespace stripped from the
     beginning and end of <parameter>str</parameter>.
     Without the second parameter,
     <function>trim</function> will strip these characters:
     <!-- sorted by importance. Printed 3 times: trim, ltrim, rtrim -->
     <itemizedlist>
      <listitem>
       <simpara>
        " " (<acronym>ASCII</acronym> <literal>32</literal> 
        (<literal>0x20</literal>)), an ordinary space.
       </simpara>
      </listitem>
      <listitem>
       <simpara>
        "\t" (<acronym>ASCII</acronym> <literal>9</literal> 
        (<literal>0x09</literal>)), a tab.
       </simpara>
      </listitem>
      <listitem>
       <simpara>
        "\n" (<acronym>ASCII</acronym> <literal>10</literal> 
        (<literal>0x0A</literal>)), a new line (line feed).
       </simpara>
      </listitem>
      <listitem>
       <simpara>
        "\r" (<acronym>ASCII</acronym> <literal>13</literal> 
        (<literal>0x0D</literal>)), a carriage return.
       </simpara>
      </listitem>
      <listitem>
       <simpara>
        "\0" (<acronym>ASCII</acronym> <literal>0</literal> 
        (<literal>0x00</literal>)), the <literal>NUL</literal>-byte.
       </simpara>
      </listitem>
      <listitem>
       <simpara> <!-- not \v, since not supported by PHP -->
        "\x0B" (<acronym>ASCII</acronym> <literal>11</literal> 
        (<literal>0x0B</literal>)), a vertical tab.
       </simpara>
      </listitem>
     </itemizedlist>
    </para>
    <para>
     You can also specify the characters you want to strip, by means
     of the <parameter>charlist</parameter> parameter.
     Simply list all characters that you want to be stripped. With
     <literal>..</literal> you can specify a range of characters.
    </para>
    <example>
     <title>Usage example of <function>trim</function></title>
     <programlisting role="php">
<![CDATA[
<?php

$text = "\t\tThese are a few words :) ...  ";

echo trim($text);           // "These are a few words :) ..."
echo trim($text, " \t."); // "These are a few words :)"

// trim the ASCII control characters at the beginning and end of $binary
// (from 0 to 31 inclusive)
$clean = trim($binary, "\x00..\x1F");

?>
]]>
     </programlisting>
    </example>
    <note>
     <simpara>
      The optional <parameter>charlist</parameter> parameter was 
      added in PHP 4.1.0
     </simpara>
    </note>
    <para>
     See also <function>ltrim</function> and <function>rtrim</function>.
    </para>
   </refsect1>
  </refentry>

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