Re: [Swig-user] Float/Double values converting incorrectly from C to Python

[William S F. <ws...@fu...>]

Steven Damer wrote:
> I'm seeing a problem with moving double values from C to python.
> Values from C are being converted into large integer values in python
> - for example, 3.5 is converted to 1080033280.0.  Here's the test code
> that I wrote:
> C file:
> float testfloat()
> {
>   return 3.5;
> }
> 
> int testint()
> {
>   return 3;
> }
> 
> double testdouble()
> {
>   return 3.5;
> }
> 
> float testfloatreflect(float f)
> {
>   return f;
> }
> 
> double testdoublereflect(double d)
> {
>   return d;
> }
> 
> int testintreflect(int i)
> {
>   return i;
> }
> 
> .i file
> extern float testfloat();
> extern int testint();
> extern double testdouble();
> extern float testfloatreflect(float f);
> extern double testdoublereflect(double d);
> extern int testintreflect(int i);
> Output that I get in python:
>>>> import NFGames
>>>> NFGames.testint()
> 3
>>>> NFGames.testfloat()
> 1080033280.0
>>>> NFGames.testdouble()
> 1.0
>>>> NFGames.testintreflect(4)
> 4
>>>> NFGames.testfloatreflect(4.5)
> 0.0
>>>> NFGames.testdoublereflect(4.5)
> 1074921472.0
> 
> I suspect that I'm seeing memory addresses instead of values, but I'm
> not sure why, or what I need to do to correct it.  Thanks for looking
> at this.
> 

You don't mention any versions of anything. I just checked and it works
for me using swig-1.3.29, python-2.4.2, gcc-4.1 and I'd be surprised if
it doesn't work on any other platform as it is a pretty common scenario.
I suggest you look at your compiler flags and/or use a C debugger to
test what the matter is. Also suggest you run the tests that come with
SWIG to check that the known working cases are working... run 'make
check-python-test-suite' in the top level directory or run the examples
in Examples/python.

William