Hexadecimal floats

[Joseph S. Myers]

Does C++ include hexadecimal floating point constants?  How does it define 
preprocessing numbers?

In the course of updating extend.texi to allow for features now being in
C99, I noticed that G++ objects to hexadecimal floats with -pedantic, but
still lexes them as numbers in cases where they can't be lexed as numbers
in C90 (see gcc.dg/c90-hexfloat-2.c), even with -ansi.

-- 
Joseph S. Myers
jsm28@cam.ac.uk