reading altitude in VB 6

[Graham Pollitt]

Hi,

This is the first time that I have been playing around with SDK and have quick question. I am trying to read Altitude using the below code but I always get an 'overflow' error.

What type would the altitude variable be considering it is 8bytes long? I have currently defined it as long.

If FSUIPC_Read(&H570, 8, VarPtr(altitude), dwResult) Then

' "Read" proceeded without any problems

If FSUIPC_Process(dwResult) Then

' "Process" proceeded without any problems

lblAltitude.Caption = Int((altitude * 3.28084) / (65536 * 65536))

Else

' Unable to "Process"

lblError.Caption = "Processing: " & ResultText(dwResult)

End If

Else

' Unable to "Read"

lblError = "Reading: " & ResultText(dwResult)

End If

Many thanks

Graham

[Pete Dowson]

What type would the altitude variable be considering it is 8bytes long? I have currently defined it as long.

Unless it's a 64-bit compiler (for a 64-bit processor), a normal "long" won't be long enough. I don't know VB -- someone may chip in and help out -- but if you read the description of what is in 0570 again you will see that it would be possible to read the 8 bytes into two "longs" in an array (or even use two separate reads into two separate longs). The first will contain the fractional metres and the second the whole number of metres. You'd need to treat the fraction as unsigned, though, and I know that is next-to-impossible in VB. In my opinion, from what I have learned here, VB is a very frustrating language I'm afraid.

Pete