btrieve-Api and VB

akasus · #1 (**permalink**) 11-18-03, 16:12

Hello,

I call the btrieve API with Code 5 (get equal) from VB and I get the error number 21 if I use a key greater then 0.

The size of the key buffer is great enouth, and if I use the key number 0 everything ist fine.

The code is:

KeyBuffer$ = "12345 "
KeyBufLen = Len(KeyBuffer)
keynum = KeyNumber
BufLen = Len(DataBuf)
Status = BTRCALL(pGetType, PosBlock, DataBuf, BufLen, ByVal KeyBuffer$, KeyBufLen, keynum)

Thanx for help.

Soner

mirtheil · #2 (**permalink**) 11-18-03, 17:54

This is because of the way VB passes strings to DLL functions. VB converts all strings to Unicode and so you end up with two bytes for every character. Btrieve is only expecting one byte. The way you work around this is to create UDTs for each of your key types and pass the UDT as the KeyBuffer for example:

Code:

'key struct for Key 0
type typIdx0
  value as string * 6
end type

'key struct for Key 1
type typIdx1
  ID as integer
end type

'key struct for Key 2
type typIdx2
  somethingelse as string * 20
end type

Then when you want to issue the Get Equal (op code 5), you do something like:

Code:

dim KeyBuf0 as typIdx0
KeyBuf0.value = "12345 "
KeyBufLen = Len(KeyBuf0)
keynum = KeyNumber
BufLen = Len(DataBuf)
Status = BTRCALL(pGetType, PosBlock, DataBuf, BufLen, ByVal KeyBuf, KeyBufLen, keynum)

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