OpenEuphoria

Bitten by a bug

• Posted by DB James <larch at adelphia.net> Oct 19, 2005
• 903 views

Hi,

This may be known to some others, but I wasted some time figuring this out, so
I'm passing along the information.

There is a problem dividing atoms by a number that only showed up when the
program was compiled to C.  In the process of clarifying it, I wrote this little
test program:

--------------------------------------------
--test.ex
--test effect of compiling using WATCOM C/C++ Version 11.0c
--run first without compiling, then with compiling
integer fn
atom x
puts(1,"Adding data to result.txt\n\n")
fn=open("c:\\euphoria\\result.txt","a")
puts(fn,"Test results for values of x (set at 75 before each operation)\n\n")
x=75
x=x/100
printf(fn,"With \"x=x/100\": x=%f\n",x)
x=75
x=x/100.0
printf(fn,"With \"x=x/100.0\": x=%f\n",x)
x=75
x/=100
printf(fn,"With \"x/=100\": x=%f\n",x)
x=75
x/=100.0
printf(fn,"With \"x/=100.0\": x=%f\n",x)
puts(fn,"\nEnd test results for values of x\n\n")
close(fn)
puts(1,"Done, any key...\n")
while equal(get_key(),-1) do end while
--------------------------------------------

The results were as follows:

First, without compiling the test program:

--------------------------------------------
Test results for values of x (set at 75 before each operation)

With "x=x/100": x=0.750000
With "x=x/100.0": x=0.750000
With "x/=100": x=0.750000
With "x/=100.0": x=0.750000

End test results for values of x
--------------------------------------------

Then, with compiling:

--------------------------------------------
Test results for values of x (set at 75 before each operation)

With "x=x/100": x=44169448.000000
With "x=x/100.0": x=0.750000
With "x/=100": x=44169452.000000
With "x/=100.0": x=0.750000

End test results for values of x
--------------------------------------------

Ironically, when I was trying to track down this bug, I tested for everything
but the real culprit, so lost some time...

--Quark