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

Hi monks! i'm trying to communicate with a DLL I have and pass two string variables to it, and get back a double. It isn't returning anything. There are no errors during debugging, but $prwin gets calle. I used the example from cpan. Any help would be greatly appreciated. Here part of my pl file: 
use Win32::API;

sub pl_prwin
{
    my $prwin;
    my $hands;
    my $board;
    my $GetPrwin;
    my $lpBuffer;
    my $return;
    
    $hands = "AhKh|Td9s|QQ+,AQs+,AQo+|JJ-88|XxXx|XxXx|XxXx";
    $board = "Ks7d4d";
    
    $GetPrwin = new Win32::API(
        "OH-DLL.dll", "prwin1($hands, $board)", 'PP', 'N');
    
    $lpBuffer = " " x 80;
    $return = $GetPrwin->Call(80, $lpBuffer);
    $lpBuffer =~ s/\0.*$//;
    $prwin  = $lpBuffer;
    
    return $prwin;
}

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Re: Win32::API question
by ikegami (Patriarch) on Apr 25, 2009 at 03:13 UTC
    You mixed and matched the 2- and 4-arg version, and you don't actually pass your arguments?! 
    use Win32::API;

my $prwin1 = Win32::API->new('OH-DLL.dll', 'prwin1', 'PP', 'D')
    or die("Error linking to prwin1: $^E\n");

sub pl_prwin
{
    my $hands = "AhKh|Td9s|QQ+,AQs+,AQo+|JJ-88|XxXx|XxXx|XxXx";
    my $board = "Ks7d4d";
    return $prwin1->Call($hands, $board);
}

    [download]

    Update: Fixed return type, as per tye's reply. Forgot to check that. Also added error message.

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[d/l]
      Thank you, unfortunately that didn't work. Is there any thing I need to check on the DLL side?
[reply]

        According to the docs, Win32::API, 'N' is long. For double, you want 'D'.

        Anybody ever tell you that "didn't work" is a pretty useless error report? :)

        - tye        

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