Re: Calling win32:api dll with pointer to array

From perldoc Win32::API:

The third parameter, the input parameter list, specifies how many
arguments the function wants, and their types. It MUST be passed
as a list reference. The following forms are valid:

    [a, b, c, d]
    \@LIST
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so make up a reference to an anonymous list as:

my $arr = [ pack("d",1), pack("d",1.5), pack("d",3) ];

# or as I would do it...

my $arr = [ map { pack 'd', $_ } ( 1, 1.5, 3 ) ];
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The [] square brackets make an anonymous array so the scalar $arr (which you need to supply to the Call method of Win32::API) contains a reference to that array.

You could as easily do:

my @arr = map { pack 'd', $_ } ( 1, 1.5, 3 );
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and then pass a reference to the list (\@arr) - whichever you prefer.

Hope this helps

   larryk                                          
perl -le "s,,reverse killer,e,y,rifle,lycra,,print"

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(tye)Re2: Calling win32:api dll with pointer to array by tye (Sage) on Jan 14, 2002 at 19:41 UTC
No, the documentation that you quote is talking about the third argument to the new() method, which certain shouldn't contain packed `double` values. It is talking about the argument `[P, I]` in the code above. The array of doubles is an argument to the C API being accessed and so gets passed in via the Call() method. Note that I avoid using the style found in the Win32::API documentation and would rewrite the code as: `my $obj= Win32::API->new( "dll", "Function", [qw( P I )], 'I' );` so that I could use strict with it. - tye (but my friends call me "Tye")	[reply] [d/l] [select]

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(tye)Re2: Calling win32:api dll with pointer to array
by tye (Sage) on Jan 14, 2002 at 19:41 UTC

No, the documentation that you quote is talking about the third argument to the new() method, which certain shouldn't contain packed double values. It is talking about the argument [P, I] in the code above.

The array of doubles is an argument to the C API being accessed and so gets passed in via the Call() method.

Note that I avoid using the style found in the Win32::API documentation and would rewrite the code as: my $obj= Win32::API->new( "dll", "Function", [qw( P I )], 'I' ); so that I could use strict with it.

tye

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