On Tue, Apr 26, 2011 at 12:24:40PM +0200, Kraus Philipp wrote:
> Hello,
>
> I read / write strings in my HDF files to copy data between Matlab and my C++
> code. I have some problems with ASCII Codes greater 127 in my files.
Then they aren't ASCII codes since ASCII only defines those
between 0 and 127 and I guess that's were the problems starts...
> The dump of a HDF5 file (Matlab) shows:
> GROUP "/" {
> DATASET "data" {
> DATATYPE H5T_STRING {
> STRSIZE 2;
> STRPAD H5T_STR_NULLTERM;
> CSET H5T_CSET_ASCII;
> CTYPE H5T_C_S1;
> }
> DATASPACE SIMPLE { ( 4 ) / ( 4 ) }
> DATA {
> (0): "\37777777744", "\37777777766", "\37777777774", "\37777777737"
This is basically '0xE4', '0xF6', '0xFC' and '0xDF', which are
'ä', 'ö', 'ü' and 'ß' in e.g. the ISO-8859-1 encoding. Of course
modulo the length of the values, they are output as 32-bit while
a char would typically only have 8.
> }
> }
> }
>
> The chars are "ä", "ö", "ü", "ß". My code creates the same chars of a string
> with string.c_str() to:
> GROUP "/" {
> DATASET "test" {
> DATATYPE H5T_STRING {
> STRSIZE 3;
> STRPAD H5T_STR_NULLTERM;
> CSET H5T_CSET_ASCII;
> CTYPE H5T_C_S1;
> }
> DATASPACE SIMPLE { ( 4 ) / ( 4 ) }
> DATA {
> (0): "\37777777703\37777777644", "\37777777703\37777777666",
> (2): "\37777777703\37777777674", "\37777777703\37777777637"
> }
The first number is '0xC3' and '0xA4', which is the UTF-8 represen-
tation of 'ä' (didn't check the rest, but the '0xC3' at the start
of all of them smells a lot like they all are UTF-8).
> }
> }
>
> It seems that my code create 2 bytes for the ä, ö, ü, ß and Matlab 1 byte.
> Can I switch the encoding in the HDF5 file or can I use unicode or anything
> else?
Don't know if you can get MatLab to use UTF-8, concerning the
HDF5 file the question is how it is written. The program it's
written by seems to use UTF-8. Can you change that? If this
is a test program with the 'äöüß' hard-coded into it you just
may have to get your editor to use ISO-8859-1. Writing to the
HDF5 file isn't the point, it just contains what you told it
to, the problem is passing in the values you want it to con-
tain.
Regards, Jens
--
\ Jens Thoms Toerring ________ [email protected]
\_______________________________ http://toerring.de
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