VB/WinAPI/Graphics, How to get a pointer to a byte array in vb4 or vb5

How to get a pointer to a byte array in vb4 or vb5

Author	Message
Stephan Brunne #1 / 7	How to get a pointer to a byte array in vb4 or vb5 Hi I need to pass a pointer to a byte array (unicode) to an api function. My question is now, how I can get this pointer (address) into a vb long variable? Any help appreciated Stephan Brunner
Tue, 09 Nov 1999 03:00:00 GMT

Ben Bair #2 / 7	How to get a pointer to a byte array in vb4 or vb5 This is a multi-part message in MIME format. ------=_NextPart_000_01BC6769.EBFD3C00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Use the VarPtr() function. It's not documented, but it's there. Don't = know if it's in VB4, but VB5's got it. Assuming you pass the length of = the byte array as well, you just call it like this: myPtr =3D VarPtr(ByteArray(0)) ... or whatever the lower bound of the array is. -- -- Ben SiteBuilder Network Level 2 Ben's VB5 Page -- This site has been Activated! http://www.{filter}highway.com/~psy/ Requires IE3.01 or higher... Stephan Brunner wrote in article = I need to pass a pointer to a byte array (unicode) to an api function. My question is now, how I can get this pointer (address) into a vb long variable? ------=_NextPart_000_01BC6769.EBFD3C00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML 3.2//EN"> <HTML> <HEAD> <META content=3Dtext/html;charset=3Diso-8859-1 = http-equiv=3DContent-Type> <META content=3D'"Trident 4.71.0544.0"' name=3DGENERATOR> </HEAD> <BODY> <P><FONT face=3DArial size=3D2>Use the VarPtr() function. It's not = documented, but=20 it's there. Don't know if it's in VB4, but VB5's got it. Assuming you = pass the=20 length of the byte array as well, you just call it like this:</FONT> <P><FONT face=3DArial size=3D2>myPtr =3D VarPtr(ByteArray(0))</FONT> <P><FONT face=3DArial size=3D2>... or whatever the lower bound of the = array is.<BR> --<BR> <HTML><BODY><FONT size=3D2>-- Ben<BR> SiteBuilder Network Level 2<BR> Ben's VB5 Page -- This site has been Activated!<BR> <A=20 href=3D"http://www.{filter}highway.com/~psy/">http://www.{filter}highway.com/~p= sy/</A><BR> Requires IE3.01 or higher...<BR> </FONT></FONT> <P><FONT face=3DArial size=3D2> <EM><FONT color=3D#808080>Stephan=20 <HTML><BODY>I need to pass a pointer to a byte array (unicode) to an api = function.<BR> My question is now, how I can get this pointer (address) into a vb = long<BR> variable?<BR> </FONT></EM><FONT size=3D2><BR> </FONT></FONT></P> </BODY></HTML> ------=_NextPart_000_01BC6769.EBFD3C00--
Tue, 09 Nov 1999 03:00:00 GMT

Chris Spies #3 / 7	How to get a pointer to a byte array in vb4 or vb5 Depending on how the call is declared you may need only pass the parameter as bytearray(0). VarPtr -- as well as StrPtr and ObjPtr -- are available in VB4, but you must declare them out of vb4 runtime DLL. If I can find the calls again I'll post them. -- -Chris Use the VarPtr() function. It's not documented, but it's there. Don't know if it's in VB4, but VB5's got it. Assuming you pass the length of the byte array as well, you just call it like this: myPtr = VarPtr(ByteArray(0)) ... or whatever the lower bound of the array is. -- -- Ben SiteBuilder Network Level 2 Ben's VB5 Page -- This site has been Activated! http://www.{filter}highway.com/~psy/ Requires IE3.01 or higher... I need to pass a pointer to a byte array (unicode) to an api function. My question is now, how I can get this pointer (address) into a vb long variable? ----------
Tue, 09 Nov 1999 03:00:00 GMT

Schmid #4 / 7	How to get a pointer to a byte array in vb4 or vb5 Quote: > Hi > I need to pass a pointer to a byte array (unicode) to an api function. > My question is now, how I can get this pointer (address) into a vb long > variable? Hi Stephan! Ben points right, the VB4-Declare is: Declare Function VarPtr Lib "vb40032" (V As Any) As Long If you want to pass a VB-Unicode-String, do'nt do something like that: pStrg = VarPtr(ByVal Strg) pStrg will be a valid Pointer to a BSTR, but VB has than already made a Unicode-to-Ansi-Conversion. You probably use it this way, but something like this will sure work: Dim ByteArr() As Byte ByteArr = Strg pStrg = VarPtr(ByteArr(0)) In VB5 there is a Function StrPtr but I have'nt tested it yet. Olaf!
Tue, 09 Nov 1999 03:00:00 GMT

irwinhurs #5 / 7	How to get a pointer to a byte array in vb4 or vb5 Maybe I don't understand the question but, if you are passing the pointer to the array as a parameter then why not pass it ByRef which will automatically pass the pointer to the array for you. This seems like the most obvious solution unless I am completely overlooking something (Which is not unlikely). Irwin Quote: > > Hi > > I need to pass a pointer to a byte array (unicode) to an api function. > > My question is now, how I can get this pointer (address) into a vb long > > variable? > Hi Stephan! > Ben points right, the VB4-Declare is: > Declare Function VarPtr Lib "vb40032" (V As Any) As Long > If you want to pass a VB-Unicode-String, do'nt do something like that: > pStrg = VarPtr(ByVal Strg) > pStrg will be a valid Pointer to a BSTR, but VB has than already made a > Unicode-to-Ansi-Conversion. > You probably use it this way, but something like this will sure work: > Dim ByteArr() As Byte > ByteArr = Strg > pStrg = VarPtr(ByteArr(0)) > In VB5 there is a Function StrPtr but I have'nt tested it yet. > Olaf!
Tue, 09 Nov 1999 03:00:00 GMT

Schmid #6 / 7	How to get a pointer to a byte array in vb4 or vb5 Quote: > Maybe I don't understand the question but, if you are passing the > pointer to the array as a parameter then why not pass it ByRef which > will automatically pass the pointer to the array for you. Hi Irwin! Thats right, but in some cases you really need the VarPtr-Function. Stephan was not writing that he pass the Byte-Array directly. If it is part of an ByRef passed User-Defined-Type than he must use the VarPtr()-Function to fill a Long-Member wich points to a Unicode-Byte-Array. Type TypeWithUnicodeByteArr pByteArr as Long ... End Type This Type-Declare does'nt work: Type TypeWithUnicodeStrg UniStrg as String 'takes 4 Bytes ... End Type UniStrg is here a Pointer to an BSTR, but after passing a UDT to a DLL-Function all contained Unicode-Strings are converted to ANSI. Another Type: Type TypeWithUnicodeByteArrDirect ByteArr() as Byte 'takes 4 Bytes ... End Type Here's the first Member also a Pointer, but it points not directly to the Arrays first Position. It points to another struct (the Pointer to the start of the Byte-Array is located at Byte-Position 13-16) Olaf!
Wed, 10 Nov 1999 03:00:00 GMT

irwinhurs #7 / 7	How to get a pointer to a byte array in vb4 or vb5 Schidt, Thanks for clearing that up. Irwin. But what would you do with a brain if you had one? Dorthy - "Wizzard of Ozz"
Mon, 15 Nov 1999 03:00:00 GMT

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