Long Double variables in 64 bit C, and User Manuals available?

[happilymambo]

I'm wondering, before I download Pelles C, how many significant digits are contained in a 64 bit long double variable. I've been using a 32 bit version of ANSI C, and I can get 18 or 19 significant digits in my answers if I use long doubles -- can I expect to get about twice as many significant digits if I download and use Pelles C? Also, are there any user manuals or other help available for Pelles C, and if so, are they available in English? Thanks in advance for any answers.

[frankie]

floats, doubles and long doubles have the same precision for 32 and 64 bits systems because their dimensions are handled by the FPU.
FPU executes all calculations with 80 bits, then the result is converted to the required variablle.

[czerny]

Pelle has answerd this concerning C99 standard here. But you can do this at our wish list.

An other interesting point to this is this older discussion.