php-doc-en/reference/filesystem/functions/fopen.xml

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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.fopen">
 <refnamediv>
  <refname>fopen</refname>
  <refpurpose>Opens file or URL</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>resource</type><methodname>fopen</methodname>
   <methodparam><type>string</type><parameter>filename</parameter></methodparam>
   <methodparam><type>string</type><parameter>mode</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>use_include_path</parameter><initializer>false</initializer></methodparam>
   <methodparam choice="opt"><type>resource</type><parameter>context</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>fopen</function> binds a named resource, specified by
   <parameter>filename</parameter>, to a stream. 
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>filename</parameter></term>
     <listitem>
      <para>
       If <parameter>filename</parameter> is of the form "scheme://...", it
       is assumed to be a URL and PHP will search for a protocol handler
       (also known as a wrapper) for that scheme. If no wrappers for that
       protocol are registered, PHP will emit a notice to help you track
       potential problems in your script and then continue as though
       <parameter>filename</parameter> specifies a regular file.
      </para>
      <para>
       If PHP has decided that <parameter>filename</parameter> specifies
       a local file, then it will try to open a stream on that file.
       The file must be accessible to PHP, so you need to ensure that
       the file access permissions allow this access.
       If you have enabled &safemode;,
       or <link linkend="ini.open-basedir">open_basedir</link> further
       restrictions may apply.
      </para>
      <para>
       If PHP has decided that <parameter>filename</parameter> specifies
       a registered protocol, and that protocol is registered as a
       network URL, PHP will check to make sure that
       <link linkend="ini.allow-url-fopen">allow_url_fopen</link> is
       enabled. If it is switched off, PHP will emit a warning and
       the fopen call will fail.
      </para>
      <note>
       <para>
        The list of supported protocols can be found in <xref
        linkend="wrappers"/>. Some protocols (also referred to as
        <literal>wrappers</literal>) support <literal>context</literal>
        and/or &php.ini; options. Refer to the specific page for the
        protocol in use for a list of options which can be set. (e.g.
        &php.ini; value <literal>user_agent</literal> used by the
        <literal>http</literal> wrapper).
       </para>
      </note>
      <para>
       On the Windows platform, be careful to escape any backslashes
       used in the path to the file, or use forward slashes.
       <informalexample>
        <programlisting role="php">
<![CDATA[
<?php
$handle = fopen("c:\\folder\\resource.txt", "r");
?>
]]>
        </programlisting>
       </informalexample>
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       The <parameter>mode</parameter> parameter specifies the type of access
       you require to the stream.  It may be any of the following:
       <table>
        <title>
         A list of possible modes for <function>fopen</function>
         using <parameter>mode</parameter>
        </title>
        <tgroup cols="2">
         <thead>
          <row>
           <entry><parameter>mode</parameter></entry>
           <entry>Description</entry>
          </row>
         </thead>
         <tbody>
          <row>
           <entry><literal>'r'</literal></entry>
           <entry>
            Open for reading only; place the file pointer at the
            beginning of the file.
           </entry>
          </row>
          <row>
           <entry><literal>'r+'</literal></entry>
           <entry>
            Open for reading and writing; place the file pointer at
            the beginning of the file.
           </entry>
          </row>
          <row>
           <entry><literal>'w'</literal></entry>
           <entry>
            Open for writing only; place the file pointer at the
            beginning of the file and truncate the file to zero length.
            If the file does not exist, attempt to create it.
           </entry>
          </row>
          <row>
           <entry><literal>'w+'</literal></entry>
           <entry>
            Open for reading and writing; place the file pointer at
            the beginning of the file and truncate the file to zero
            length.  If the file does not exist, attempt to create it.
           </entry>
          </row>
          <row>
           <entry><literal>'a'</literal></entry>
           <entry>
            Open for writing only; place the file pointer at the end of
            the file. If the file does not exist, attempt to create it.
           </entry>
          </row>
          <row>
           <entry><literal>'a+'</literal></entry>
           <entry>
            Open for reading and writing; place the file pointer at
            the end of the file. If the file does not exist, attempt to
            create it.
           </entry>
          </row>
          <row>
           <entry><literal>'x'</literal></entry>
           <entry>
            Create and open for writing only; place the file pointer at the
            beginning of the file.  If the file already exists, the
            <function>fopen</function> call will fail by returning &false; and
            generating an error of level <constant>E_WARNING</constant>.  If
            the file does not exist, attempt to create it.  This is equivalent
            to specifying <literal>O_EXCL|O_CREAT</literal> flags for the
            underlying <literal>open(2)</literal> system call. 
           </entry>
          </row>
          <row>
           <entry><literal>'x+'</literal></entry>
           <entry>
            Create and open for reading and writing; otherwise it has the
            same behavior as <literal>'x'</literal>.
           </entry>
          </row>
          <row>
           <entry><literal>'c'</literal></entry>
           <entry>
            Open the file for writing only. If the file does not exist, it is
            created. If it exists, it is neither truncated (as opposed to
            <literal>'w'</literal>), nor the call to this function fails (as is
            the case with <literal>'x'</literal>). The file pointer is
            positioned on the beginning of the file. This may be useful if it's
            desired to get an advisory lock (see <function>flock</function>)
            before attempting to modify the file, as using
            <literal>'w'</literal> could truncate the file before the lock
            was obtained (if truncation is desired,
            <function>ftruncate</function> can be used after the lock is
            requested).
           </entry>
          </row>
          <row>
           <entry><literal>'c+'</literal></entry>
           <entry>
            Open the file for reading and writing; otherwise it has the same
            behavior as <literal>'c'</literal>.
           </entry>
          </row>
         </tbody>
        </tgroup>
       </table>
      </para>
      <note>
       <para>
        Different operating system families have different line-ending
        conventions.  When you write a text file and want to insert a line
        break, you need to use the correct line-ending character(s) for your
        operating system.  Unix based systems use <literal>\n</literal> as the
        line ending character, Windows based systems use <literal>\r\n</literal>
        as the line ending characters and Macintosh based systems use
        <literal>\r</literal> as the line ending character.
       </para>
       <para>
        If you use the wrong line ending characters when writing your files, you
        might find that other applications that open those files will "look
        funny".
       </para>
       <para>
        Windows offers a text-mode translation flag (<literal>'t'</literal>)
        which will transparently translate <literal>\n</literal> to
        <literal>\r\n</literal> when working with the file.  In contrast, you
        can also use <literal>'b'</literal> to force binary mode, which will not
        translate your data.  To use these flags, specify either
        <literal>'b'</literal> or <literal>'t'</literal> as the last character
        of the <parameter>mode</parameter> parameter.
       </para>
       <para>
        The default translation mode depends on the SAPI and version of PHP that
        you are using, so you are encouraged to always specify the appropriate
        flag for portability reasons.  You should use the <literal>'t'</literal>
        mode if you are working with plain-text files and you use
        <literal>\n</literal> to delimit your line endings in your script, but
        expect your files to be readable with applications such as notepad.  You
        should use the <literal>'b'</literal> in all other cases.
       </para>
       <para>
        If you do not specify the 'b' flag when working with binary files, you
        may experience strange problems with your data, including broken image
        files and strange problems with <literal>\r\n</literal> characters.
       </para>
      </note>
      <note>
       <para>
        For portability, it is strongly recommended that you always
        use the 'b' flag when opening files with <function>fopen</function>.
       </para>
      </note>
      <note>
       <para>
        Again, for portability, it is also strongly recommended that
        you re-write code that uses or relies upon the <literal>'t'</literal>
        mode so that it uses the correct line endings and
        <literal>'b'</literal> mode instead.
       </para>
      </note>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>use_include_path</parameter></term>
     <listitem>
      <para>
       The optional third <parameter>use_include_path</parameter> parameter
       can be set to '1' or &true; if you want to search for the file in the
       <link linkend="ini.include-path">include_path</link>, too.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>context</parameter></term>
     <listitem>
      &note.context-support;
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a file pointer resource on success, or &false; on error.
  </para>
 </refsect1>

 <refsect1 role="errors">
  &reftitle.errors;
  <para>
   If the open fails, an error of level
   <constant>E_WARNING</constant> is generated.  You may use <link
   linkend="language.operators.errorcontrol">@</link> to suppress this
   warning.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>4.3.2</entry>
       <entry>
        As of PHP 4.3.2, the default mode is set to binary for all platforms
        that distinguish between binary and text mode.  If you are having
        problems with your scripts after upgrading, try using the
        <literal>'t'</literal> flag as a workaround until you have made your
        script more portable as mentioned before
       </entry>
      </row>
      <row>
       <entry>4.3.2</entry>
       <entry>
        The <literal>'x'</literal> and <literal>'x+'</literal> options were
        added
       </entry>
      </row>
      <row>
       <entry>5.2.6</entry>
       <entry>
        The <literal>'c'</literal> and <literal>'c+'</literal> options were
        added
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>fopen</function> examples</title>
    <programlisting role="php">
<![CDATA[
<?php
$handle = fopen("/home/rasmus/file.txt", "r");
$handle = fopen("/home/rasmus/file.gif", "wb");
$handle = fopen("http://www.example.com/", "r");
$handle = fopen("ftp://user:password@example.com/somefile.txt", "w");
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  &warn.ssl-non-standard;
  &note.sm.uidcheck.dir;
  <para>
   If you are experiencing problems with reading and writing to files and
   you're using the server module version of PHP, remember to make sure that
   the files and directories you're using are accessible to the server
   process.
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><xref linkend="wrappers"/></member>
    <member><function>fclose</function></member>
    <member><function>fgets</function></member>
    <member><function>fread</function></member>
    <member><function>fwrite</function></member>
    <member><function>fsockopen</function></member>
    <member><function>file</function></member>
    <member><function>file_exists</function></member>
    <member><function>is_readable</function></member>
    <member><function>stream_set_timeout</function></member>
    <member><function>popen</function></member>
    <member><function>stream_context_create</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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