We have a c source file: something.c

[source, c]
------------------
int xmode(char** str)
{
  (*str)[0] = 'X';
	(*str) ++; // xmode modified *str
	return 0;
}
------------------

Setup a perl6 file, use NativeCall call function xmode: something.p6

[source, perl6]
-----------------
#!/usr/bin/env perl6

use v6;
use NativeCall;

sub xmode(CArray[Str]) returns int32 is native('xmode') { * }

my CArray[Str] $astr .= new;

$astr[0] = "54654";

say xmode($astr);

say $astr[0]; // rakudo output -> "4654"
-----------------

So, how to get orignal string "X4654" in pelr6 side .