<?php

declare(strict_types=1);

const LINES = 5;
const INDEX = 10;
        
$file_01 = new SplTempFileObject();
$file_02 = new SplFileObject('/tmp/test.txt', 'w+');

// write to files
for ($i = 0; $i < LINES; $i++) {
    $file_01->fwrite("line {$i}" . PHP_EOL);
    $file_02->fwrite("line {$i}" . PHP_EOL);
}

// reset
$file_01->rewind();
$file_02->rewind();

// seek
$file_01->seek(INDEX);
$file_02->seek(INDEX);

// show results
echo 'file_01: ' . $file_01->key(), PHP_EOL;
echo 'file_02: ' . $file_02->key(), PHP_EOL;