[Bug c/11914] New: comparing doubles

[Bug c/11914] New: comparing doubles

[birger dot b at gmx dot net]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11914

           Summary: comparing doubles
           Product: gcc
           Version: 3.2.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: birger dot b at gmx dot net
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux

Overview Description: More detailed expansion of summary.

Drag-selecting any page crashes Mac builds in NSGetFactory

Steps to Reproduce: 
Compile and run

Actual Results:
Program's output:
shouldn't be here
ok!
ok!

Expected Results:
ok!
ok!
ok!

Build Date & Platform:
[lee@yavin strange]$ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2.2/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --with-system-zlib --enable-__cxa_atexit --host=i386-redhat-linux
Thread model: posix
gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)


Additional Builds and Platforms:
On sparc-sun-solaris2.6 the output is also not as expected but not
the same as on Linux:
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-solaris2.6/2.95.2/specs
gcc version 2.95.2 19991024 (release)

Program's output:
ok!
shouldn't be here
ok!

The following is the *.i file:
# 1 "exp.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "exp.c"
int printf(const char *format, ...);

double two = 2;
double five = 5;


const double f() {
        return five;
}

int main () {
# 21 "exp.c"
        if(two/f() == two/f()) {
                printf("ok!\n");
        }
        else {
                printf("shouldn't be here\n");
        }






  if((long double)two/f() == two/f()){
                printf("ok!\n");
        }
        else {
                printf("shouldn't be here\n");
        }






        if(two/five == two/five){
                printf("ok!\n");
        }
        else {
                printf("shouldn't be here\n");
        }
        return 0;
}

[Bug c/11914] comparing doubles

[birger dot b at gmx dot net]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11914



------- Additional Comments From birger dot b at gmx dot net  2003-08-14 05:24 -------
Created an attachment (id=4602)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=4602&action=view)
Preprocessed source code exp.i

[Bug c/11914] comparing doubles

[ehrhardt at mathematik dot uni-ulm dot de]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11914


ehrhardt at mathematik dot uni-ulm dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


------- Additional Comments From ehrhardt at mathematik dot uni-ulm dot de  2003-08-14 07:28 -------
Though often reported this is not a bug. See the section
titled "Problems with floating point computations." on 
http://gcc.gnu.org/bugs.html.


*** This bug has been marked as a duplicate of 323 ***