[PPL-devel] Precision of doubles and stdio

Hi there,

the following little program

#include <stdio.h>

int main() { double d; scanf("%lf", &d); printf("%.1000g\n", d); return 0; }

does this on Linux/i686

$ gcc -W -Wall in.c $ a.out 70.9 70.900000000000005684341886080801486968994140625

and does the following under Cygwin on the same machine:

roberto@quark /tmp $ gcc -W -Wall in.c

roberto@quark /tmp $ ./a.exe 70.9 70.90000000000000568434188608080148696899414

Why? Is there a way to reconcile the two behaviors? Notice that I know about the x87 and its vaguaries: nonetheless I wonder why such a scanf immediately followed by a printf shows a difference between Cygwin and Linux. All the best,

Roberto