Hi, I am new to this list. If this is not the correct place for posting the question I apologize for any inconvenience.
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 ); cout.precision( 20 ); cout << "Original value : " << val << endl; cout << "Double with mult : " << d << endl; cout << "Casted to long v1 : " << l << endl; cout << "Casted to long v2 : " << l2 << endl; cout << "Casted to long v3 : " << l3 << endl; cout << "Casted to long v4 : " << l4 << endl; On a 64bit machine the output is (as expected): Original value : 52.305819999999997094 Double with mult : 188300952 Casted to long v1 : 188300952 Casted to long v2 : 188300952 Casted to long v3 : 188300952 Casted to long v4 : 188300952 Nevertheless on a 32bit machine and gcc 4.6.1 and 4.6.3 I get: Original value : 52.305819999999997094 Double with mult : 188300952 Casted to long v1 : 188300952 Casted to long v2 : 188300951 Casted to long v3 : 188300951 Casted to long v4 : 188300951 I obtain the results by compiling with -m32. The differences between v1 and v2 or v3, v4 are very strange and I have no explanation. Furthermore, if I compile with optimization turned on (-O3) both results are correct and identical. Is there an explanation for this behavior or is this already a known issue? I have also tested with gcc-4.7 and everthing looks correct for 32 and 64 bit. Thank you!
