Help with a structure declaration please

Quote:

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FROM MSDN...
JOYCAPS
The JOYCAPS structure contains information about the joystick capabilities.

typedef struct {
WORD wMid;
WORD wPid;
CHAR szPname[32];
UINT wXmin;
UINT wXmax;
UINT wYmin;
UINT wYmax;
UINT wZmin;
UINT wZmax;
UINT wNumButtons;
UINT wPeriodMin;
UINT wPeriodMax;
UINT wRmin;
UINT wRmax;
UINT wUmin;
UINT wUmax;
UINT wVmin;
UINT wVmax;
UINT wCaps;
UINT wMaxAxes;
UINT wNumAxes;
UINT wMaxButtons;
CHAR szRegKey[32];
CHAR szOEMVxD[260];
} JOYCAPS;

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Can someone tell me how to declare this structure in VB please?

I am trying to update an API call taht was originally coded in VB6 and now I have translated that into VB.net. But the extended version of that structure is as outlined above and I need to use that instead.

I cannot find any examples of VB.net code for this. I think I'd need to use some kind of <attribute> tag but I am at a loss.

Maybe one of you gurus can help? Its mainly the 3 CHAR arrays that I am having trouble with.

Instead of char arrays put StringBuilders and set it's max capacity to the desired numbers

You could also have members of your structure as arrays of Byte's where the structure has CHAR arrays and then do the conversion to a string for your use...not real efficient, but would probably work well enough...

HTH

Hume

I couldn't use stringbuilders, but the helpful error message that it prompted told me to use strings instead and initialise them in a certain manner, which I did.

This is what I now have:

VB Code:

Private Structure JOYCAPS
        Dim Mid As Short
        Dim Pid As Short
        Dim Pname As String
        Dim Xmin As Integer
        Dim Xmax As Integer
        Dim Ymin As Integer
        Dim Ymax As Integer
        Dim Zmin As Integer
        Dim Zmax As Integer
        Dim NumButtons As Integer
        Dim PeriodMin As Integer
        Dim PeriodMax As Integer
        Dim Rmin As Integer
        Dim Rmax As Integer
        Dim Umin As Integer
        Dim Umax As Integer
        Dim Vmin As Integer
        Dim Vmax As Integer
        Dim Caps As Integer
        Dim MaxAxes As Integer
        Dim NumAxes As Integer
        Dim MaxButtons As Integer
        Dim RegKey As String
        Dim OEMVxD As String
    End Structure

But when I call the function with this structure (after initialising relevant properties) I get a return (error) code of 165. I have no idea what this code means and apparently no means of finding out. It could be anything from an unexpected data structure, to ANYTHING.

I can't believe MSDN just leaves this structure like this without further info.

Any ideas guys?

Try this...Make your RegKey an Array of Bytes (and any other strings as well, assuming this is a C Type structure)

...
RegKey(32) as Byte
...

Then inside whatever routine you are writing, you will need to assemble a string based on the Byte indexes using the ASC function

Also, the UINT could give you problems as well, since this is an unsigned INT which VB doesn't have. It is not the same as an Integer or Short.

Lastly, I'm not sure if it will let you have a Structure member named Mid (since this is an intrinsic VB function)

HTH

Hume

Sorry, should use the Chr function, not the Asc...

Quote:

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Also, the UINT could give you problems as well, since this is an unsigned INT which VB doesn't have. It is not the same as an Integer or Short.

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Not true, System.uint16 and system.uint32. I would try using these for the WORD and UINT variables as Short and Integer are both signed variables.

I'm not bothered about the actual contents of the char arrays. I just need to get the structure compatible with the API call first. I tried your suggestion, it compiles without error, but it still returns the mystery 165 code.

Most puzzling.

Have you looked at this line

Dim Mid As Short

Mid seems to be a keyword, maybe that is messing you up? Not sure.

Sean,

How do I do that in VB6.0? VB.NET, no problem, but I'm not sure how to access that in 6.0...

Whoops, wrong forum. Thought this one was in Visual Bsaic Classic...sheepish grin