gzseek

(PHP 4, PHP 5, PHP 7, PHP 8)

gzseek — Seek on a gz-file pointer

说明

gzseek(resource $stream, int $offset, int $whence = SEEK_SET): int

Sets the file position indicator for the given file pointer to the given offset byte into the file stream. Equivalent to calling (in C) gzseek(zp, offset, SEEK_SET).

If the file is opened for reading, this function is emulated but can be extremely slow. If the file is opened for writing, only forward seeks are supported; gzseek() then compresses a sequence of zeroes up to the new starting position.

参数

stream

The gz-file pointer. It must be valid, and must point to a file successfully opened by gzopen().

offset

The seeked offset.

whence

whence values are:

SEEK_SET - Set position equal to offset bytes.
SEEK_CUR - Set position to current location plus offset.

If whence is not specified, it is assumed to be SEEK_SET.

返回值

Upon success, returns 0; otherwise, returns -1. Note that seeking past EOF is not considered an error.

范例

示例 #1 gzseek() example


<?php
$gz = gzopen('somefile.gz', 'r');
gzseek($gz,2);
echo gzgetc($gz);
gzclose($gz);
?>

参见

gztell() - Tell gz-file pointer read/write position
gzrewind() - Rewind the position of a gz-file pointer

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User Contributed Notes 2 notes

down

liuhaifeng at example dot com ¶

9 years ago


Since seek after the end is not considered an error, I doubt that "while (gzseek ($fh, $eof) == 0) $eof += $d;" will get into infinite loop.

down

dperham at wgate dot com ¶

17 years ago


PHP/4.3.9
contrary to the notes, gzseek() returns -1 if I try to seek past the end of the file.  here is a function that will return the last seekable position, and put the file pointer there.

/** sets the file pointer at the end of the file
 *  and returns the number of bytes in the file.
 */
function gzend($fh)
{
   $d   = 1<<14;
   $eof = $d;
   while ( gzseek($fh, $eof) == 0 ) $eof += $d;
   while ( $d > 1 )
   {
      $d >>= 1;
      $eof += $d * (gzseek($fh, $eof)? -1 : 1);
   }
   return $eof;
}

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官方地址：https://www.php.net/manual/en/function.gzseek.php

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PHP官方手册 - 互联网笔记

gzseek

说明

参数

返回值

范例

参见

User Contributed Notes 2 notes