[ITK-dev] Define for is "char" is signed or unsigned

[Bradley Lowekamp]

Thanks for the the info.

I wonder if this is related to any of the Debian IO test failures on other platforms.

Looks like ARM may also have char as the unsigned variety.
http://www.arm.linux.org.uk/docs/faqs/signedchar.php

Brad

On May 28, 2014, at 8:55 AM, Miller, James V (GE Global Research) <millerjv at ge.com> wrote:

> vxl_platform_tests.cxx has a section for VCL_CHAR_IS_SIGNED.
> 
> My recollection is that almost all of our systems make the same assumptions about the sign of a char.  I think it was the SGI, however, that assumed the opposite convention.
> 
> Jim
> 
> -----Original Message-----
> From: Insight-developers [mailto:insight-developers-bounces at itk.org] On Behalf Of Bradley Lowekamp
> Sent: Wednesday, May 28, 2014 8:41 AM
> To: ITK
> Subject: [ITK-dev] Define for is "char" is signed or unsigned
> 
> Hello,
> 
> Where is a define to determine if type "char" is signed or unsigned. I am pretty sure it's already some place in ITK, KWSys or VXL, I just can't find it.
> 
> I am looking to address this issue:
> https://issues.itk.org/jira/browse/SIMPLEITK-393
> 
> 
> It's uncommon knowledge that char, signed char, and unsigned char are three distinct types and that char may be signed or unsigned.
> 
> The ImageIOBase is unaware of this:
> https://github.com/InsightSoftwareConsortium/ITK/blob/master/Modules/IO/ImageBase/include/itkImageIOBase.h#L687-L703
> 
> 
> So the following line is system dependent an "buggy"..
> IMAGEIOBASE_TYPEMAP(char, CHAR);
> 
> I may just be easiest to add:
> IMAGEIOBASE_TYPEMAP(signed char, CHAR);
> 
> Which is what the assumption that has been made, presumably...
> 
> Thoughts?
> 
> Thanks,
> Brad
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