Search code examples
phppackphp-5.5

Simulate pack('J') in php < 5.6

I would need pack('J', $val) in php 5.5 but 'J' is supported in 5.6 onwards only.

How can I simulate it in php-5.5? It is not really necessary to pack all 64 bits.

My try does not seem to be correct (on Win7 64bit):

pack('J', $val) === pack('N', 0) . pack('N', $val)
Solution

  • There's probably a smarter way to do this, but this works:

    // base_convert() will treat your value as a string here,
// converting it from decimal to hexadecimal
$hexStringValue = base_convert($your64bitInteger, 10, 16);

// Pad with zeros to the left, until pack()'s output length is matched
$hexStringValue = str_pad($hexStringValue, 16, '0', STR_PAD_LEFT);

// Convert to binary
$packed64bitInteger = hex2bin($hexStringValue);

    I must note however, PHP 5.5 reached EOL in July 2016 and you should be upgrading to at least version 5.6 anyway.