http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47146
--- Comment #5 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 2011-01-03 18:01:11 UTC --- On Mon, Jan 03, 2011 at 05:12:10PM +0000, babelart at yahoo dot com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47146 > > Sorry, I was not specific enough. It is the integer conversion that seem > to be wrong,for example the following two lines: > > fprintf( stdout, "Float 100.0 * 0.3894949=%d\n", 100.0 * elapsed ); > fprintf( stdout, "Float 100 * 0.3894949=%d\n", 100 * elapsed ); > > both produce the value '-536870912'. > > I also downloaded the C99 integer to float conversion test code; and they > generated two many failures. I also believe the compiler should round > resulting > integer values when stripping decimals off. > > Regards, > Pierre Innocent > Compile the code with -Wall and fix all the warnings. #include <stdio.h> int main (void) { float elapsed; elapsed = 0.3894949; /* Note, the rhs is a double! */ printf("Float 100.0 * 0.3894949=%d\n", 100.0 * elapsed ); printf("Float 100 * 0.3894949=%d\n", 100 * elapsed ); return 0; } troutmask:kargl[208] cc -o z -Wall a.c a.c: In function 'main': a.c:7: warning: format '%d' expects type 'int', but argument 2 has type 'double' a.c:8: warning: format '%d' expects type 'int', but argument 2 has type 'double' Your printf statements are using the first 4 bytes of the 8 byte double argument.
