Count lines number on big files

gistfile1.php

<?php
$file = new SplFileObject("mybigfile.csv");

// Store flags and position
$flags = $file->getFlags();
$current = $file->key();

// Prepare count by resetting flags as READ_CSV for example make the tricks very slow
$file->setFlags(null);

// Go to the larger INT we can as seek will not throw exception, errors, notice if we go beyond the bottom line
$file->seek(PHP_INT_MAX);

// We store the key position
// As key starts at 0, we add 1
$count = $file->key() + 1;

// We move to old position
// As seek method is longer with line number < to the max line number, it is better to count at the beginning of iteration
$file->seek($current);

// Re set flags
$file->setFlags($flags);

echo $count.PHP_EOL;