RE: Java char *INOUT doesn't OUT

signed char* is treated as a pointer to an array by default so does not handle 
null terminated strings. The signed char*INOUT typemaps are for single 
characters. If you want an in/out string, you'll have to use StringBuffer and 
debug/modify the SBUF typemaps in the Examples/java/typemaps example to suite. 

William

>-----Original Message-----
>From: swig-admin@xxxxxxxxxxxxxxx [mailto:swig-admin@xxxxxxxxxxxxxxx]On
>Behalf Of Gary Nissen
>Sent: 23 September 2004 20:22
>To: William S Fulton
>Cc: swig@xxxxxxxxxxxxxxx
>Subject: Re: [Swig] Java char *INOUT doesn't OUT
>
>
>William,
>
>Thanks for the input.  For clarification, the char* are 
>basically strings (not single chars) that are passed back and 
>forth with this DLL.
>
>Does the signed char * properly handle null terminating the Strings?
>
>Thanks,
>
>Gary
>
>
>At 04:06 PM 9/22/2004, William S Fulton wrote:
>>Gary Nissen wrote:
>>
>>>Hi,
>>>I'm using SWIG-1.3.22 on Windows with Java JDK 1.4.2.
>>>I'm trying to wrap a C DLL.  All parameters are passed as 
>pointers (int *, double *, and char *).  Most parameters are 
>*INPUT, but some are *INOUT.  The int *INOUT and double *INOUT 
>work as expected by turning the parameter into a single 
>dimensional array.  But a char *INOUT turns the parameter into 
>a String, basically making it a char *INPUT.
>>>I expected the char *INOUT to allow me to pass Strings back 
>and forth via a 1-dimensional array just like int *INOUT.  Am 
>I off track?  Is there a better method to do this?
>>>Through my struggles I also tried the *SBUF and *BYTE 
>methods.  Unfortunately neither worked for me.  
>>>The *SBUF caused Access Violations because the char array 
>was a different length than the string contained in the 
>StringBuffer.  It was using the capacity of a StringBuffer 
>instead of the length of the String contained in it.  I tried 
>changing the typemap to use length.  Then I received Access 
>Violations when the resulting string was being appended back 
>to the StringBuffer.  I wasn't able to figure out why that was failing.
>>>The *BYTE caused garbage to be pasted back into my String.  
>I was using the BYTE method this way:
>>>String s = "0123456789";
>>>byte[] b = s.toByteArray();
>>>int r = DLLWrapper.getResult(b);
>>>s = new String(b);
>>>System.out.println(s);
>>>This resulted in garbage printouts.
>>>Any advice on the best/easiest way to do this?  
>>
>>SWIG wraps char* as a string, that is well documented. To 
>change the behaviour of char* to a pointer to an in/out single 
>char character, apply the 'signed char *' typemaps.
>>
>>%include "typemaps.i"
>>%apply signed char *INOUT {char *pnum};
>>%typemap(freearg) char *pnum "";
>>
>>void foo(char *pnum);
>>
>>Unfortunately the default char* typemaps require a freearg 
>typemap and this is still picked up, thus the extra typemap 
>above to clear the freearg typemap. I'll change this so it 
>won't be necessary in the future.
>>
>>William
>>_______________________________________________
>>Swig maillist  -  Swig@xxxxxxxxxxxxxxx
>>http://mailman.cs.uchicago.edu/mailman/listinfo/swig
>
>
>
>_______________________________________________
>Swig maillist  -  Swig@xxxxxxxxxxxxxxx
>http://mailman.cs.uchicago.edu/mailman/listinfo/swig
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