in reply to Calling c functions from perl...

<lang mode="C">I'm kind of curious - without the nul terminator, how does your C code know the length of input, or the length of the output, for that matter? I would have to think that you would need size_t's for the sizes of the buffers.</lang>

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Re^2: Calling c functions from perl...
by ajaffres (Novice) on May 18, 2005 at 15:47 UTC
    The length is worked out withing the functions. I want to pass the a pointer only (not the whole array). I hope to create either an array or a string in perl and to pass the address of the array/string to the functions. Therefore, there is no need to pass the length.
[reply]
      SWIG will handle the input parameter for you without any typemap, but for the output parameter you need a way to get its length in order to convert it back to an SV and a typemapto do so.

      Look for perl5/typemaps.i in the SWIG Lib directory, you will find there some samples of how to handle output parameters... just grep for OUTPUT.

[reply]
        Thank you very much for your answers.

        But in reply to salva, I seems that perl/swig doesn't understand 'unsigned char *' when I pass a string to my function.

        In Perl I wrote this:
        $message = 'Hello';
        &MyCProgram::CopyString($message);

        In my C program I wrote that in order to test simpy test the input (I will need to output something later):
        void CopyString(unsigned char *string1) {
        FILE *pf;
        pf = fopen("test.txt","w+");
        fputs(string1,pf);
        fclose(pf);
        }

        And finally we can find this in my interface file:
        %apply unsigned char *INPUT { unsigned char *string1 };
        extern void CopyString(unsigned char *string1);

        When I run my Perl program, I get this error message:
        Argument "Hello" isn't numeric in subroutine entry at ./index1.pl line 21.

        The problem here is that Perl expects a value and not a string. Ideally I would like to pass only the real address of my string.

        Have you got any idea how to solve my problem? Any help is welcomed! Merci beaucoup!

        Arnaud
[reply]

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