<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >php_stream_seek</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="PHP 手册" HREF="index.html"><LINK REL="UP" TITLE="Streams Common API Reference" HREF="streams.common-api.html"><LINK REL="PREVIOUS" TITLE="php_stream_flush" HREF="streams.php-stream-flush.html"><LINK REL="NEXT" TITLE="php_stream_tell" HREF="streams.php-stream-tell.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >PHP 手册</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="streams.php-stream-flush.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="streams.php-stream-tell.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="streams.php-stream-seek" ></A >php_stream_seek</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN252752" ></A >php_stream_seek -- Reposition a stream</DIV ><DIV CLASS="refsect1" ><A NAME="AEN252755" ></A ><H2 >Description</H2 >int <B CLASS="methodname" >php_stream_seek</B > ( php_stream * stream, off_t offset, int whence )<BR ></BR ><P > <B CLASS="function" >php_stream_seek()</B > repositions the internal position of <CODE CLASS="parameter" >stream</CODE >. The new position is determined by adding the <CODE CLASS="parameter" >offset</CODE > to the position indicated by <CODE CLASS="parameter" >whence</CODE >. If <CODE CLASS="parameter" >whence</CODE > is set to <TT CLASS="constant" ><B >SEEK_SET</B ></TT >, <TT CLASS="constant" ><B >SEEK_CUR</B ></TT > or <TT CLASS="constant" ><B >SEEK_END</B ></TT > the offset is relative to the start of the stream, the current position or the end of the stream, respectively. </P ><P > <B CLASS="function" >php_stream_seek()</B > returns 0 on success, but -1 if there was an error. </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > Not all streams support seeking, although the streams API will emulate a seek if <CODE CLASS="parameter" >whence</CODE > is set to <TT CLASS="constant" ><B >SEEK_CUR</B ></TT > and <CODE CLASS="parameter" >offset</CODE > is positive, by calling <B CLASS="function" >php_stream_read()</B > to read (and discard) <CODE CLASS="parameter" >offset</CODE > bytes. </P ><P > The emulation is only applied when the underlying stream implementation does not support seeking. If the stream is (for example) a file based stream that is wrapping a non-seekable pipe, the streams api will not apply emulation because the file based stream implements a seek operation; the seek will fail and an error result will be returned to the caller. </P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="streams.php-stream-flush.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >起始页</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="streams.php-stream-tell.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >php_stream_flush</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="streams.common-api.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >php_stream_tell</TD ></TR ></TABLE ></DIV ></BODY ></HTML >