Working with binary data in PHP

Question

I'm writing a client for a binary socket protocol in PHP, and it's a pain. I'm currently using pack to convert numbers into binary strings, but it's lacking. Two options pack has are:

• Write a signed 32 bit integer in machine byte order
• Write an insigned 32 bit integer in big endian byte order

But I need to write signed 32 bit integers in big endian order, as with Java's DataOutputStream.writeInteger. pack doesn't have that option.

Is there a way to do this with pack, or to transform the output of pack, or maybe a better library for working with binary data in PHP?

• Russell Dias: Not sure if this helps, but here goes: phpclasses.org/package/…

Answer 1

Do you use the Zend Framework? If so, you can use the function Zend_Io_Writer::writeInt32BE()

Writes signed 32-bit integer as big-endian ordered binary data to the stream.

Or else you should take a look at the ZF-source how these guys handle this.

Answer 2

The specification for PHP's pack() says that the unsigned/signed distinction only matters for unpack(), not pack().

So just use the 32 bit network byte order option (N).

• Bart van Heukelom: + 4 billion, doesn't that result in the same number? I also suspect this isn't very portable, see stackoverflow.com/questions/300840/force-php-integer-overflow
• caf: @Bart vna Heukelom: On further reflection, and checking the documentation, you can just use the unsigned option.