3v4l.org

run code in 300+ PHP versions simultaneously
<?php function dechex_size($val, $size) { if ($size < 1) { error_log("Invalid value for $size"); return false; } $bits = $size << 2; if ($bits > log(PHP_INT_MAX, 2)) { return dechex($val); } $mask = 0; for ($i = 0; $i < $size; ++$i) { $mask = ($mask << 4) | 0xF; } $val &= $mask; return sprintf("%x", $val); } echo dechex_size(15,4), "\n"; // gives 000f echo dechex_size(-1,16), "\n"; // gives ffffffffffffffff echo dechex_size(-1,2), "\n"; // gives ff echo dechex_size(1025,2), "\n"; // gives ? (either 401, 01, ff, or false)
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
f ffffffffffffffff ff 1

preferences:
218.32 ms | 403 KiB | 287 Q