use File::Spec::Win32;
my $wdir = 'C:/strawberry';
$wdir =~ s[:][]g;
$wdir =~ /(.*)/;
print File::Spec::Win32->catfile('C:/cache', $1), "\n";

##</code><code>##

C:\cache\C\strawberry

##</code><code>##

C:\cache\C: