SplFileObject::seek

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

SplFileObject::seek — Seek to specified line

说明

public SplFileObject::seek(int $line): void

Seek to specified line in the file.

参数

line: The zero-based line number to seek to.

返回值

没有返回值。

错误／异常

Throws a LogicException if the line is negative.

范例

示例 #1 SplFileObject::seek() example

This example outputs the third line of the script which is found at position 2.


<?php
$file = new SplFileObject(__FILE__);
$file->seek(2);
echo $file->current();
?>

以上例程的输出类似于：

$file->seek(2);

参见

SplFileObject::current() - Retrieve current line of file
SplFileObject::key() - Get line number
SplFileObject::next() - Read next line
SplFileObject::rewind() - Rewind the file to the first line
SplFileObject::valid() - Not at EOF

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User Contributed Notes 2 notes

down

ahmad_maqsood at waku-2 dot com ¶

4 years ago


A sleek way of counting the number of lines in a file can be like below

$file = new \SplFileObject('file.extension', 'r');
$file->seek(PHP_INT_MAX);

echo $file->key() + 1;

down

info at inatica dot com ¶

9 months ago


there is a bug using fseek on previos versions of PHP8.0.1
See:

https://bugs.php.net/bug.php?id=46569

https://3v4l.org/O89dJ

I solved it with a function:

<?php
/**
* SEEK an Spl object
* There is a bug in php for seeking files
* seems solved php_version > PHP8.0.1
* See https://bugs.php.net/bug.php?id=46569
* & https://3v4l.org/O89dJ
*
* $Spl->seek() Works ok in all versions with offset 0 (first row)
* On PHP_VERSION < 8.0.1:
*  - Offset 1: seek() cannot seek at row 1. It will be done manually, rewind file and reading first row
*  - Rest of Offsets: The cursor remains at next row of $Offset
*
* @param SplObject $Spl
* @param int $Offset
*/

function seek_spl($Spl, $Offset){
    if (version_compare(PHP_VERSION, '8.0.1', '>=') || $Offset == 0) {
        $Spl->seek($Offset);
    } else {
        if( $Offset == 1 ){
            $Spl->rewind(); // Ensure to go at first row before exit
            $Spl->fgets(); // Read line 0. Cursor remains now at line 1
        } else {
            $Spl->seek($Offset-1);
        }
    }
}?>

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