use Win32::API;

my $filename="C:/Windows/ieuninst.exe";
my $Api = new Win32::API("fileversion.dll", "GetFileVersionTxt", P, P);

# Set some memory aside for the returned value
my $output = "\x00" x 1024;

# Call the function in the dll
$Api->Call($filename,$output);

# Remove the unused padding in the string

my $final = ($output =~ /(.*?)\x00/);
print "\output - $final";