Need help in data conversion... 1

[elziko]

Can anyone give me any help in converting a Long into its constituent four Bytes?

Cheers

elziko

 

[elziko]

Doh! I meant to say a Single not a long.

At the moment I'm working on using an API function to get the address of an array which contains a bunch of Singles and then I wanna try to read each succesive byte into a byte array.

Any thoughts?

elziko

 

[SJA]

Elziko,
There are several ways to do this :-
One is to use LSET to assign the memory contents of one user
defined variable into another eg ....

Private Type Typ_4Byte
Byte1 As Byte
Byte2 As Byte
Byte3 As Byte
Byte4 As Byte
End Type

Private Type Typ_Single
Byte_All As Single
End Type

Dim Four_Bytes As Typ_4Byte
Dim Floater1 As Typ_Single

'put code here to assign your floating point number to
'variable Floater1.Byte_All

lset Four_Bytes = Floater1

'Floater1.Byte1 to Byte4 will contain the individual bytes
'that comprised the single.

 

[elziko]

Yeah, thanks very much.

I need a little more advice, from anyone!

Using the advice above I have now stored an array of Singles in a Byte array.

The only problem is the array of Singles is two dimensional. If it was only a single dimension I would know that I can create a Single on every forth byte in the Byte array and that would enable me to rebuild the Single array.

With a two dimensional array I need to know when a new 'column' in the second dimension starts so that I can recreate it.

I've tried setting one of the entries in the byte array to NULL enabling me to iterate through the Byte array and start a new column in the rebuilt Single array every time I encounter a NULL.

However, I have found that its not possible to assign a value of NULL to a byte.

How else could I do this?

cheers,

elziko

 

[elziko]

I've sorted i now by storing the number of columns in the first byte of the byte array.

But if anyone has any comments or better ways of doing this.......

 

[jjames]

You can use the CopyMemory api...

Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(ByRef lpvDest As Any, ByRef lpvSource As Any, _
ByVal cbCopy As Long)

example...

Dim bytLongs(0 to 3) '4 bytes only for 1 long, increase as needed
Dim lngPointer as Long
Dim lngNumber as Long

lngPointer = 0
lngNumber = 4563

CopyMemory(bytLongs(lngPointer), lngNumber, 4)


'increment lngPointer by 4 before copying next long value to byte array

 

[jjames]

Dim bytLongs(0 to 3) as byte

syntax for CopyMemory....

CopyMemory bytLongs(lngPointer), lngNumber, 4