how to write a C function and be able to call it from perl -

i have been programming c while. need write c program perl can call. should have same syntax following dummy perl function: take 2 inputs, both strings (may contain binary characters, "\x00"), output new string.

of course, algorithm of function more complex, that's why need in c.

sub dummy {     ($a, $b) = @_;     return $a . $b; } 

i have briefly looked @ swig implementation, taking input/ouput other integer not easy, hope can give concrete example.

thanks in advance.

update: got great example rob (author of inline::c module in cpan), thanks!

############################## use warnings; use strict; use devel::peek;  use inline c => config => build_noisy => 1, ;  use inline c => <<'eoc';  sv * foo(sv * in) {  sv * ret;   strlen len;  char *tmp = svpv(in, len);  ret = newsvpv(tmp, len);  sv_catpvn(ret, tmp, len);  return ret;  }  eoc  $in = 'hello' . "\x00" . 'world'; $ret = foo($in);   dump($in); print "\n"; dump ($ret);  ############################## 

perl has glue language called xs kind of thing. knows mappings between perl data types , c types. example, c function

char *dummy(char *a, int len_a, char *b, int len_b); 

could wrapped xs code

module = foo    package = foo  char * dummy(char *a, int length(a), char *b, int length(b)); 

the foo.xs file compiled when module installed, relevant build tool chains have support xs.

argument conversion code generated automatically, function can called in perl foo::dummy("foo", "bar"), once xs code has been loaded perl:

package foo; use parent 'dynaloader'; foo->bootstrap; 

there xs tutorial in perl documentation, , reference documentation in perlxs.

xs choice modules, awkward one-off scripts. inline::c module allows embed glue c code directly perl script , take care of automatic compilation whenever c code changes. however, less code can generated automatically approach.