Re: [Swig-user] How to pass a char array back to java via SWIG and have it treated as a byte array ?

[Andrew M. <and...@db...>]

"Navnidhi Sharma" <Nav...@us...> wrote on 25/09/2007 
15:04:52:

> Use vector of chars in your wrapper.

My C wrapper does return a vector of chars. The return type is char*. 
Maybe you had something else in mind. Did you think my code was in C++? 
After all, C++ has a vector type. This code has to be in C so the C++ 
vector type is not available for me.

I saw in a post from years ago the following:

SWIG maps char * to a Java String, that is clearly documented. So it is
expecting the char * to be NULL terminated. Sounds like your data is not
NULL terminated, in which case you could apply the signed char[] typemaps.

%include "arrays_java.i"
%typemap(out) signed char[]
%{$result = SWIG_JavaArrayOutSchar(jenv, (signed char *)$1,
strlen($1)/*FillMeInAsSizeCannotBeDeterminedAutomatically*/); %}
%apply signed char[] {char *}

I don't understand this. It looks like it is using strlen so that would 
not work for me. The data is binary and a zero byte could easily be 
present. But I tried it anyway and it didn't work. The java output was 
unchanged. The getters and setters for my char* data were still expressed 
using the java String type.

> Thanks,
> Navnidhi

> -----Original Message-----
> From: swi...@li...
> To: swi...@li...
> Subject: [Swig-user] How to pass a char array back to java via SWIG and
> have it treated as a byte array ?

> I am using SWIG to wrap a closed-source third-party API. One of the 
> routines in the API returns a block of bytes read from a binary file. In
> C 
> the routine that does this returns a char* (and a length as well).  I
> have 
> written a little C wrapper around the API so that I can have a simple 
> header that can be SWIG'd. My routine also returns a char*.  The 
> SWIG-generated code treats this as a string and uses the java String
> type. 
> How do I make it use a byte array instead please?

Regards,

Andrew Marlow
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