how to get the value of last executed command in strawberry perl

I am trying to execute a simple strawberry perl script for file copy to get the code from the last executed command. But I get 0/success in all the case.

Code from my test.pl script

use File::Copy;  
use strict;
use warnings;

my $source_file = "D:\\abc\\def\\in\\test\\test1.csv";
my $target_file = "D:\\abc\\def\\in\\test\\test2.csv";

if ( copy( $source_file, $target_file ) == 0 ) {
    print "success";
} 
else { print "fail"; }

Since the path I used D:\\abc\\def\\in\\test\\test1.csv does not exist on the machine so I expect to get fail but I get success no matter what I provide.

Following the execution and output:

D:\pet\common\bin\backup>perl test.pl
success

If you look at perldoc File::Copy you will see the following:

RETURN
    All functions return 1 on success, 0 on failure. $! will be set if an
    error was encountered.

Therefore, your code should be exposing what is in $! if there is an error:

if ( copy($source_file, $target_file)) {
    print "success\n";
} 
else { 
    warn "fail: $!\n";
}

Also, as described in the documentation for File::Copy, copy returns 1 on success (a true value), so I removed your == 0 in the success test. With Perl, any true value in the if(COND){...} statement will do; you don't need to explicitly test for 1.

Regarding paths: The / character can be used as a path delimiter, even if you're using Windows except in some cases where you might be sending the path to an external program. This capability allows you to relatively portably write code that expresses paths as foo/bar/baz, and it will work with Windows similarly to how it would work under a *nix operating system. Using the forward slash as a delimiter allows you to avoid escaping every backslash in a path: foo\\bar\\baz.