Win32::API question

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

Fellow monks,
I think Win32::API could be the answer to my problem anyway. I've been asked to change a perlscript to interface with a dll (something I've never done before). The function I want to call in the dll looks like this

INT GetFileVersionTxt(STRING sFile, out STRING sVersion)
[download]

as you guessed it simply outputs a version number for a particular file. Here's as far as I got (badly):

#!usr/bin/perl
use Win32::API;
my $filename="C:/WINNT/ieuninst.exe";
$Api = new Win32::API(fileversion.dll, GetFileVersionTxt, [P,$filename
+], [P,$output]);
print "\output - $output";
[download]

I used the Filversion module before, didn't have any problems, this dll gives slightly different results, which my managers would prefer to get, otherwise I wouldn't have to call it.Any pointers as to how I can get this working would be greatly appreciated.
Jonathan

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Re: Win32::API question by Ninthwave (Chaplain) on Jun 02, 2004 at 18:04 UTC
You create dthe API object but you need to return a result from a call to that object. Note I do not have the dll in question so I can not test but I would think your code should look like this: `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";` [download] This is from an example in Chapter 9 of Win32 API from Win32 Perl Programming by David Roth modified to match your criteria. I would like to play with dll to test this as I think it would need some tweaking to run. I also suggest reading the pod for Win32::API as they have some excellent examples of getting data in and out of the functions loaded. "No matter where you go, there you are." BB	[reply] [d/l]
Re: Re: Win32::API question by Ven'Tatsu (Deacon) on Jun 02, 2004 at 18:16 UTC
`my $Api = new Win32::API("fileversion.dll", "GetFileVersionTxt", P, P) +;` [download] should be changed to `my $Api = new Win32::API("fileversion.dll", "GetFileVersionTxt", ['P', + 'P'], 'I');` [download] or `my $Api = new Win32::API("fileversion.dll", "GetFileVersionTxt", 'PP', + 'I');` [download] The third parameter is suposed to be a string or array ref of the input parameters, and the forth is a string for the return value.	[reply] [d/l] [select]
Re: Re: Re: Win32::API question by Ninthwave (Chaplain) on Jun 02, 2004 at 19:36 UTC
Cheers I alway forget the single quotes. I usually catch errors like that if I test code. But I was running from work without a dll to use. Oh well, maybe next time my first reply will be better ;) But than Win32::API for me is always sitting with a sample and changing it to meet my needs based on the functions called. Funny enough to see what got added to the meditations How to make Win32::API easy to use "No matter where you go, there you are." BB	[reply]