usage libc in perl, how using char's?

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

#include <stdio.h>
int tst(int len,char str[1024]){
printf("called c from perl len:'%i'  str:'%s'  \n",len, str);
return 1;
}
int main(  ){
tst(54,"char");
return 1;
}
[download]

then what's wrong here, in C it works well, module for perl

compiled well, but this 
use TST;
TST::test(4444,"ss");

prints called c from perl len:'4444'  str:'(null)'
[download]

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Re: usage libc in perl, how using char's? by Corion (Patriarch) on Apr 29, 2010 at 08:06 UTC
How are you linking your Perl code to the C code? Are you using Inline::C? Otherwise, if you pass in a Perl scalar, you will need to use the appropriate macros to get at the data payload. To get at the string part of a scalar, you need to use `char* strval = SvPV(str);` [download] I recommend looking at illguts to learn about the low level Perl data structures.	[reply] [d/l]
Re: usage libc in perl, how using char's? by samarzone (Pilgrim) on Apr 29, 2010 at 08:34 UTC
I don't know much about linking Perl and C but there is one thing which got my attention. Your function name is `tst` in C while it is `test` in perl. Is is the way it should be?	[reply] [d/l] [select]
Re^2: usage libc in perl, how using char's? by gants (Novice) on Apr 29, 2010 at 11:14 UTC
char* strval = SvPV(str); that's been wrong I did C-module to PERL, it's opposite using PERL in C-lang. that's my source which I'm using as C-module to PERL. `int tst(int len,char **str) { printf("called c from perl len:'%i' str:'%s' \n", len, str); return 1; }` [download] Your function name is tst in C while it is test in perl. Is is the way it should be? no, of course not, because I've posted there different outputs from just c-programm and module compiled to perl and called from perl, above...	[reply] [d/l]