How to handle large integers in Tcl8.4?

[Fermulator]

I'm trying to do some fancy footwork with HEX numbers. Basically, I want to take a HEX number, convert to decimal, add some number (integer) to it, and convert it back to HEX.

% set hex 0xFFFFFFFFFFFF
0xFFFFFFFFFFFF
% set hexInDec [expr $hex]
281474976710655
% set decBackToHex [format %x $hexInDec]
integer value too large to represent
while evaluating {set hexBackToHex [format %x $hexInDec]}

 

[Fermulator]

Thanks to "dgp" on freenode for this tip!

% set decBackToHex [format %lx $hexInDec]
ffffffffffff

As per the "OPTIONAL SIZE MODIFIER" notation on

http://tmml.sourceforge.net/doc/tcl/format.html.