On Wed, Aug 1, 2012 at 1:52 PM, Karsten Ahnert <karsten.ahn...@ambrosys.de> wrote: > > I am new to this list. If this is not the correct place for posting the > question I apologize for any inconvenience.
This question should have gone to gcc-h...@gcc.gnu.org. Please take any followups to gcc-help. Thanks. > The following code produces strange results on a 32 bit Linux system > with gcc 4.6.1 (compilation with -m32): > > double val = 52.30582; > double d = 3600.0 * 1000.0 * val; > long l = long( d ); > long l2 = long( ( 3600.0 * 1000.0 * val ) ); > long l3 = (long)( 3600.0 * 1000.0 * val ); > long l4 = long( 3600.0 * 1000.0 * val ); x86 32-bit floating point is weird because by default the compiler will use the 80-bit x87 floating point registers. That will cause unexpected results. Ways to avoid that are -mfpmath=sse -msse2, or -fexcess-precision=std, or -ffloat-store. Ian
