building binary data structures

Having written loads of stuff in PHP, I find myself having for the first time to generate binary data in memory - I actually need to build a native file for a drawing program in memory. The data consists mainly of lists of 32bit little endian integers - some signed and some unsigned. I've started the work, and am building the data up in a string variable. I know however that I am about to get bitten by numeric overflows. For example if I have a function create_thingy($param1,$param2) where param1 is an unsigned 32 bit int, and the top bit is set, then I suspect that php will probably represent the number as floating point, and I'll probably lose some precision. Has anybody been here before and found a good mode of working in the unsigned 32bit arena? Cheers -- Phil Driscoll Dial Solutions +44 (0)113 294 5112 http://www.dialsolutions.com http://www.dtonline.org