wsprintf I64 - how to get it to include a plus sign ?

Hello all,

OS XPsp3 :

I'm using wsprintfA (user32) with the format-string "%010I64d" to output
a provided 64-bit number.  Which works.

The thing is that I would like to see a "+" sign for the positive numbers,
and I can't seem to do it.  No matter where I put a "+" symbol in the format
string the output breaks.

Question : is there a way to get wsprintfA to include a plus sign when 
displaying decimal numbers, and if so what is it ?

Remark : I've also tried sprintf (crtdll), but it doesn't seem to understand 
either "%I64d" or "%lld".

Remark #2 : wsprintfA doesn't understand "%+d" either.  :-|

Regards,
Rudy Wieser