fread make a var use memory equals to buffer length. even if it has only few bytes

fread_memory.php

<?php

ini_set('memory_limit', '256M');

// create file
@mkdir('tmp_file');
for($i=0;$i<300;$i++){
file_put_contents("tmp_file/{$i}.txt", $i);
}

// read file
$data = [];
for($i=0;$i<300;$i++){
$fp = fopen("tmp_file/{$i}.txt", "r");
$data[$i] = fread($fp, 1024 * 1024);
fclose($fp);

echo strlen($data[$i])." ".memory_get_usage()."\n";
}