Edit D:\app\Administrator\product\11.2.0\dbhome_1\perl\html\lib\IO\Seekable.html
<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>IO::Seekable - supply seek based methods for I/O objects</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:" /> </head> <body style="background-color: white"> <table border="0" width="100%" cellspacing="0" cellpadding="3"> <tr><td class="block" style="background-color: #cccccc" valign="middle"> <big><strong><span class="block"> IO::Seekable - supply seek based methods for I/O objects</span></strong></big> </td></tr> </table> <!-- INDEX BEGIN --> <div name="index"> <p><a name="__index__"></a></p> <ul> <li><a href="#name">NAME</a></li> <li><a href="#synopsis">SYNOPSIS</a></li> <li><a href="#description">DESCRIPTION</a></li> <li><a href="#see_also">SEE ALSO</a></li> <li><a href="#history">HISTORY</a></li> </ul> <hr name="index" /> </div> <!-- INDEX END --> <p> </p> <h1><a name="name">NAME</a></h1> <p>IO::Seekable - supply seek based methods for I/O objects</p> <p> </p> <hr /> <h1><a name="synopsis">SYNOPSIS</a></h1> <pre> use IO::Seekable; package IO::Something; @ISA = qw(IO::Seekable);</pre> <p> </p> <hr /> <h1><a name="description">DESCRIPTION</a></h1> <p><code>IO::Seekable</code> does not have a constructor of its own as it is intended to be inherited by other <code>IO::Handle</code> based objects. It provides methods which allow seeking of the file descriptors.</p> <dl> <dt><strong><a name="getpos" class="item">$io->getpos</a></strong> <dd> <p>Returns an opaque value that represents the current position of the IO::File, or <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html#undef"><code>undef</code></a> if this is not possible (eg an unseekable stream such as a terminal, pipe or socket). If the <code>fgetpos()</code> function is available in your C library it is used to implements getpos, else perl emulates getpos using C's <code>ftell()</code> function.</p> </dd> </li> <dt><strong><a name="setpos" class="item">$io->setpos</a></strong> <dd> <p>Uses the value of a previous getpos call to return to a previously visited position. Returns "0 but true" on success, <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html#undef"><code>undef</code></a> on failure.</p> </dd> </li> </dl> <p>See <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html">the perlfunc manpage</a> for complete descriptions of each of the following supported <code>IO::Seekable</code> methods, which are just front ends for the corresponding built-in functions:</p> <dl> <dt><strong><a name="seek" class="item">$io->seek ( POS, WHENCE )</a></strong> <dd> <p>Seek the IO::File to position POS, relative to WHENCE:</p> </dd> <dl> <dt><strong><a name="0" class="item">WHENCE=0 (SEEK_SET)</a></strong> <dd> <p>POS is absolute position. (Seek relative to the start of the file)</p> </dd> </li> <dt><strong><a name="1" class="item">WHENCE=1 (SEEK_CUR)</a></strong> <dd> <p>POS is an offset from the current position. (Seek relative to current)</p> </dd> </li> <dt><strong><a name="2" class="item">WHENCE=2 (SEEK_END)</a></strong> <dd> <p>POS is an offset from the end of the file. (Seek relative to end)</p> </dd> </li> </dl> <p>The SEEK_* constants can be imported from the <code>Fcntl</code> module if you don't wish to use the numbers <code>0</code> <a href="#1"><code>1</code></a> or <a href="#2"><code>2</code></a> in your code.</p> <p>Returns <a href="#1"><code>1</code></a> upon success, <code>0</code> otherwise.</p> <dt><strong><a name="sysseek" class="item">$io->sysseek( POS, WHENCE )</a></strong> <dd> <p>Similar to $io->seek, but sets the IO::File's position using the system call <code>lseek(2)</code> directly, so will confuse most perl IO operators except sysread and syswrite (see <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html">the perlfunc manpage</a> for full details)</p> </dd> <dd> <p>Returns the new position, or <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html#undef"><code>undef</code></a> on failure. A position of zero is returned as the string <code>"0 but true"</code></p> </dd> </li> <dt><strong><a name="tell" class="item">$io->tell</a></strong> <dd> <p>Returns the IO::File's current position, or -1 on error.</p> </dd> </li> </dl> <p> </p> <hr /> <h1><a name="see_also">SEE ALSO</a></h1> <p><a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlfunc.html">the perlfunc manpage</a>, <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/pod/perlop.html#i_o_operators">I/O Operators in the perlop manpage</a>, <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/lib/IO/Handle.html">the IO::Handle manpage</a> <a href="file://C|\ADE\aime_smenon_perl_090715\perl\html/lib/IO/File.html">the IO::File manpage</a></p> <p> </p> <hr /> <h1><a name="history">HISTORY</a></h1> <p>Derived from FileHandle.pm by Graham Barr <<a href="mailto:gbarr@pobox.com">gbarr@pobox.com</a>></p> <table border="0" width="100%" cellspacing="0" cellpadding="3"> <tr><td class="block" style="background-color: #cccccc" valign="middle"> <big><strong><span class="block"> IO::Seekable - supply seek based methods for I/O objects</span></strong></big> </td></tr> </table> </body> </html>
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