ginttu has asked for the wisdom of the Perl Monks concerning the following question:

Hey! I am embedding some code written in C into Perl by the use of H2XS. I've been able to write little C programs like "Hello, World" and have the output come out of h2xs. 
###############
# C code
# Hello, World
void 
print_hello (void)
{
   printf("Hello, World\n");
}
###############
# XS code
# Hello, World
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

MODULE = Hello         PACKAGE = Hello

void
print_hello()

[download]

Now the next C program I would like to use is very complex! Does anyone know how to pass parameters from my command line so I can use them with my *.xs code? Any help would be appreciated!! Also, does anyone have any examples using h2xs with C libraries?? Thanks, Jennifer

Replies are listed 'Best First'.
Re: XS Library - Embedding C code in Perl
by Zaxo (Archbishop) on Nov 14, 2002 at 00:11 UTC

    Inline is fine, but it is perhaps not as well integrated into ExtUtils and module building as the standard XS interface.

    To answer your question directly, you should #include the perl headers before your C code, unless there is good reason not to. That gives you macros and functions to ease writing your functions . This example is adapted from perlxstut, which I recommend to you:

    MODULE = Foo      PACKAGE = Foo

int
is_even(input)
        int     input
    CODE:
        RETVAL = (input % 2 == 0);
    OUTPUT:
        RETVAL

    [download]

    I'd parse the command line in perl before calling library functions with the arguments.

    To link to an external lib, #include <foo.h> (its header) in the xs file, and put the linker directive '-lfoo' in Makefile.PL's LIB parameter.

    After Compline,
    Zaxo

[reply]
[d/l]
Re: XS Library - Embedding C code in Perl
by talexb (Chancellor) on Nov 13, 2002 at 22:34 UTC

    The stock answer for this question is "Use Inline::C instead". Having never used either, I can't base my recommendation on any experience .. just on what I've heard.

    --t. alex
    but my friends call me T.
[reply]
      I would concur with the comments of talexb above - I have found Inline::C to make incorporating C and Perl code together incredibly easy.

      The only thing which I would add to talexb's post is a few links for further information:

       

      perl -e 'print+unpack("N",pack("B32","00000000000000000000000111011110")),"\n"'

[reply]
[reply]
Re: XS Library - Embedding C code in Perl
by tachyon (Chancellor) on Nov 13, 2002 at 23:40 UTC
[reply]
Re: XS Library - Embedding C code in Perl
by Elian (Parson) on Nov 14, 2002 at 00:19 UTC
    Command line args are in the perl variable @ARGV, which is in the main package. You can go wading through the symbol tables for it, but it'd probably be easier to pass in a reference to it from your perl code, in case you want to use the routine on an alternate array or something.
[reply]
[d/l]

Back to Seekers of Perl Wisdom