Using function with PChar data type

  • Thread starter Thread starter Andrius B.
  • Start date Start date
A

Andrius B.

Hi all.

I would like to find out how to solve the problem using DLL functions
(written in Delphi) in VB.NET


The DLL contains a function
GetStatus (username: PChar; password: PChar; var status : PChar):integer;
it takes to input parameters (username and password) and returns 1 if
everything goes OK (status is return in variable "status" as string, like
"valid" or "expired"), and 0 if an exception occurs ("status" contains empty
string).

In VB this function is declared as
Declare Auto Function GetStatus Lib "mydll.dll" (ByVal username As IntPtr,
ByVal password As IntPtr, ByRef status As IntPtr) As Integer

The problem is how to use this function in a code.
As far as I know, the code shoul look smth like this:

Dim username as string="user1"
Dim password as string="pass1"
Dim status as New String(vbnullchar,255)

Dim userptr As New IntPtr
userptr = Marshal.StringToCoTaskMemAnsi(username & vbNullChar)
Dim passptr As New IntPtr
passptr = Marshal.StringToCoTaskMemAnsi(password & vbNullChar)
Dim statusptr As New IntPtr
statusptr = Marshal.StringToCoTaskMemAnsi(status & vbNullChar)

dim result as integer = GetStatus(userptr, passptr, statusptr)
status=marshal.PtrToStringAnsi(statusptr)


Is the code right or should be modified?

Thanks in advance.
 
Andrius said:
Hi all.

I would like to find out how to solve the problem using DLL functions
(written in Delphi) in VB.NET


The DLL contains a function
GetStatus (username: PChar; password: PChar; var status : PChar):integer;
it takes to input parameters (username and password) and returns 1 if
everything goes OK (status is return in variable "status" as string, like
"valid" or "expired"), and 0 if an exception occurs ("status" contains empty
string).

In VB this function is declared as
Declare Auto Function GetStatus Lib "mydll.dll" (ByVal username As IntPtr,
ByVal password As IntPtr, ByRef status As IntPtr) As Integer
Click to expand...

Try this

Declare Auto Function GetStatus Lib "mydll.dll" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer


Usage:

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = GetStatus("user1","pass1",h)
Dim status as string = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)

You could wrap it (wrapper after wrapper after wrapper after wrapper
<g>) with another function using the import as a primitive

Declare Auto Function primGetStatus _
Lib "mydll.dll" Alias "GetStatus" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer

Function GetStatus
( _
ByVal username As String, _
ByVal password As String, _
ByRef status As String
) as Integer

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = primGetStatus(username,password,h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
return res
End Function

--
 
Andrius said:
Hi all.

I would like to find out how to solve the problem using DLL functions
(written in Delphi) in VB.NET


The DLL contains a function
GetStatus (username: PChar; password: PChar; var status : PChar):integer;
it takes to input parameters (username and password) and returns 1 if
everything goes OK (status is return in variable "status" as string, like
"valid" or "expired"), and 0 if an exception occurs ("status" contains empty
string).

In VB this function is declared as
Declare Auto Function GetStatus Lib "mydll.dll" (ByVal username As IntPtr,
ByVal password As IntPtr, ByRef status As IntPtr) As Integer
Click to expand...

Try this

Declare Auto Function GetStatus Lib "mydll.dll" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer


Usage:

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = GetStatus("user1","pass1",h)
Dim status as string = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)

You could wrap it (wrapper after wrapper after wrapper after wrapper
<g>) with another function using the import as a primitive

Declare Auto Function primGetStatus _
Lib "mydll.dll" Alias "GetStatus" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer

Function GetStatus
( _
ByVal username As String, _
ByVal password As String, _
ByRef status As String
) as Integer

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = primGetStatus(username,password,h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
return res
End Function

--
 
Mike said:
Try this

Declare Auto Function GetStatus Lib "mydll.dll" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer


Usage:

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = GetStatus("user1","pass1",h)
Dim status as string = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)

You could wrap it (wrapper after wrapper after wrapper after wrapper
<g>) with another function using the import as a primitive

Declare Auto Function primGetStatus _
Lib "mydll.dll" Alias "GetStatus" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer

Function GetStatus
( _
ByVal username As String, _
ByVal password As String, _
ByRef status As String
) as Integer

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = primGetStatus(username,password,h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
return res
End Function
Click to expand...

Note I added the continuation "_" when posting this so it looks clean.
I missed one after the status parameter. You will catch that via compile.

I can't wait for VB.NET to evolve beyond needing _ for continuation
lines. I think I saw somewhere they deprecated it as part of the next
2010 version. :-)

--
 
Mike said:
Try this

Declare Auto Function GetStatus Lib "mydll.dll" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer


Usage:

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = GetStatus("user1","pass1",h)
Dim status as string = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)

You could wrap it (wrapper after wrapper after wrapper after wrapper
<g>) with another function using the import as a primitive

Declare Auto Function primGetStatus _
Lib "mydll.dll" Alias "GetStatus" _
( _
ByVal username As String, _
ByVal password As String, _
ByVal status As IntPtr
) as Integer

Function GetStatus
( _
ByVal username As String, _
ByVal password As String, _
ByRef status As String
) as Integer

Dim h As IntPtr = Marshal.AllocHGlobal(255)
dim res as integer = primGetStatus(username,password,h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
return res
End Function
Click to expand...

Note I added the continuation "_" when posting this so it looks clean.
I missed one after the status parameter. You will catch that via compile.

I can't wait for VB.NET to evolve beyond needing _ for continuation
lines. I think I saw somewhere they deprecated it as part of the next
2010 version. :-)

--
 
Thanks Mike.
I have tried your code (exactly as you wrote), but the same exception
occurs:
"Attempted to read or write protected memory. This is often an indication
that other memory is corrupt."
Is this because of bad variable declaration or bad calling convention?
 
Thanks Mike.
I have tried your code (exactly as you wrote), but the same exception
occurs:
"Attempted to read or write protected memory. This is often an indication
that other memory is corrupt."
Is this because of bad variable declaration or bad calling convention?
 
hmmm,

All I can think of is

1) That Status is overflowing?
2) Your delphi code is using SHORT strings vs HUGE strings?
2) Are you using a STDCALL in the DLL exporting?

How is the delphi DLL code compiled?

Your original prototype (delphi to c/c++ to VB.NET)

x : pchar --> const char *x --> byval x as string
var x : pchar --> char *x or char **x --> byref as string

the problem is that in general, when return an OUT on a string
pointer, it is generalized helped with a size parameter

preallocate string of max_size
GetString(string, max_size)

Thats the case in all languages.

But your function is assuming a fix size of 255, so you need to
preallocate that space.

Since the function is going to set the status in unmanaged memory,
you need to pass it a pointer to unmanaged memory

Dim hSpace As IntPtr = Marshal.AllocHGlobal(255)

and have the unmanaged (native) function write to it:

GetStatus(User,Pass,hSpace)

then you want to type cast the return space of bytes to a string:

status = Marshal.PtrToStringAnsi(hSpace)

So I don't see whats would be wrong based on your initial prototype
other that there is something else going on.

It all depends on whats going on in the native function. Maybe you
need to get it 254?

I have lots of similar SDK function that output strings so I know the
signature I provide works for similar function.

Try it with KERNEL32 functions like GetComputerName() which has Win32
prototype:

BOOL GetComputerName(LPTSTR lpbuffer, LPDWORD lpnsize)

in VB.NET

Declare Auto Function primGetComputerName _
Lib "kernel32.dll" Alias "GetComputerName" _
( ByVal name As IntPtr, ByRef namesize As Integer) As Boolean

Function GetComputerName( _
ByRef name As String, ByRef namesize As Integer) As Boolean
name = ""
Dim h As IntPtr = Marshal.AllocHGlobal(namesize)
dim res as boolean = primGetComputerName(h,namesize)
if res then name = Marshal.PtrToStringAuto(h)
Marshal.FreeHGlobal(h)
return res
End Function

Usage:

dim cn as string = ""
dim dw as integer = 255
if GetComputerName(cn,dw) then
Console.Writeline("-Computer Name {0} dw: {1} ",cn,dw)
end if

That function is similar to yours, the different is that a size is
passed.

I haven't touched delphi since 3.0 when they first introduced HUGE
strings but I still have products and a SDK based on it.

I did a quick DLL creation test here and you will get the same
exception if you use a StrCopy() versus a direct assignment, buts its
also wrong too.

// File: D:\Local\wcsdk\wcserver\dotnet\Sandbox\testpasdll.pas
{$H-,O+,A-}
Library MYDLL;

uses
sysutils,
windows;

function GetStatus (username: PChar;
password: PChar;
var status : PChar):integer; stdcall;
begin
//strcopy(status,'success');
status := 'success';
result := 1;
end;

///////////////////////////////////////////// EXPORT LIST
Exports
GetStatus index 1;
end.

Play with the above until you get it write :-) I ran out of the time
to figure it out.
 
hmmm,

All I can think of is

1) That Status is overflowing?
2) Your delphi code is using SHORT strings vs HUGE strings?
2) Are you using a STDCALL in the DLL exporting?

How is the delphi DLL code compiled?

Your original prototype (delphi to c/c++ to VB.NET)

x : pchar --> const char *x --> byval x as string
var x : pchar --> char *x or char **x --> byref as string

the problem is that in general, when return an OUT on a string
pointer, it is generalized helped with a size parameter

preallocate string of max_size
GetString(string, max_size)

Thats the case in all languages.

But your function is assuming a fix size of 255, so you need to
preallocate that space.

Since the function is going to set the status in unmanaged memory,
you need to pass it a pointer to unmanaged memory

Dim hSpace As IntPtr = Marshal.AllocHGlobal(255)

and have the unmanaged (native) function write to it:

GetStatus(User,Pass,hSpace)

then you want to type cast the return space of bytes to a string:

status = Marshal.PtrToStringAnsi(hSpace)

So I don't see whats would be wrong based on your initial prototype
other that there is something else going on.

It all depends on whats going on in the native function. Maybe you
need to get it 254?

I have lots of similar SDK function that output strings so I know the
signature I provide works for similar function.

Try it with KERNEL32 functions like GetComputerName() which has Win32
prototype:

BOOL GetComputerName(LPTSTR lpbuffer, LPDWORD lpnsize)

in VB.NET

Declare Auto Function primGetComputerName _
Lib "kernel32.dll" Alias "GetComputerName" _
( ByVal name As IntPtr, ByRef namesize As Integer) As Boolean

Function GetComputerName( _
ByRef name As String, ByRef namesize As Integer) As Boolean
name = ""
Dim h As IntPtr = Marshal.AllocHGlobal(namesize)
dim res as boolean = primGetComputerName(h,namesize)
if res then name = Marshal.PtrToStringAuto(h)
Marshal.FreeHGlobal(h)
return res
End Function

Usage:

dim cn as string = ""
dim dw as integer = 255
if GetComputerName(cn,dw) then
Console.Writeline("-Computer Name {0} dw: {1} ",cn,dw)
end if

That function is similar to yours, the different is that a size is
passed.

I haven't touched delphi since 3.0 when they first introduced HUGE
strings but I still have products and a SDK based on it.

I did a quick DLL creation test here and you will get the same
exception if you use a StrCopy() versus a direct assignment, buts its
also wrong too.

// File: D:\Local\wcsdk\wcserver\dotnet\Sandbox\testpasdll.pas
{$H-,O+,A-}
Library MYDLL;

uses
sysutils,
windows;

function GetStatus (username: PChar;
password: PChar;
var status : PChar):integer; stdcall;
begin
//strcopy(status,'success');
status := 'success';
result := 1;
end;

///////////////////////////////////////////// EXPORT LIST
Exports
GetStatus index 1;
end.

Play with the above until you get it write :-) I ran out of the time
to figure it out.
 
Forgot to point out, maybe it will matter by the compiler directive

{$H-}

may make a big difference. Try {$H+} as well. If I recall, it makes
a short STRING into a HUGE string. A short again, is the zero index
byte length format but its limite to 255 characters. The {$H+} makes
all those string type into C like pointer strings.

--
 
Forgot to point out, maybe it will matter by the compiler directive

{$H-}

may make a big difference. Try {$H+} as well. If I recall, it makes
a short STRING into a HUGE string. A short again, is the zero index
byte length format but its limite to 255 characters. The {$H+} makes
all those string type into C like pointer strings.

--
 
Mike said:
Forgot to point out, maybe it will matter by the compiler directive

{$H-}

may make a big difference. Try {$H+} as well. If I recall, it makes a
short STRING into a HUGE string. A short again, is the zero index byte
length format but its limite to 255 characters. The {$H+} makes all
those string type into C like pointer strings.

--
Click to expand...

Andrius,

You might have figured it out by now, if you did, pass on the info :-)

I tried to figure out why I could not get basic delphi pascal DLL to
marshal correctly. But what I did was to make sure it worked as a C dll.

---------------- cut/paste to mydll.c ------------
// file: mydll.c
// compiled like so: cl mydll.c /LD /DLL

#include <stdio.h>
#include <windows.h>

__declspec( dllexport ) int __stdcall GetStatus(char *status)
{
strcpy(status,"success from mydll.dll");
return 1;
}
------------------- cut here ------------------------

This worked calling it from C applet, VB.NET, even a delphi applet

For VB.NET, the import just like I gave you, worked fine:

' import mydll.c
Declare Auto Function cdll_GetStatus Lib "mydll.dll"
(ByVal status As IntPtr) As Integer

' wrapper
Function GetStatus(ByRef status As String) As Integer
Dim h As IntPtr = Marshal.AllocHGlobal(255)
Dim res As Integer = cdll_GetStatus(h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
Return res
End Function

Well, a Delphi DLL should work the same:

// File : testpasdll.pas
{$H-,O-,A-}
Library testpasdll;

uses
sysutils,windows;

function GetStatus(var status : pchar): integer; stdcall;
begin
StrPlCopy(status,'success from pascal dll',255);
result := 1;
end;
//////////////////////////////////// EXPORT LIST
Exports
GetStatus index 1;
end.

Its been so long that I have worked with the finer details of delphi,
but I am sure it is related to getting to the mixed string stuff in
delphi similar to how VB6 had BSTR string and fixed strings mixing.

Bu I just have not figured why the above does not marshal correctly.
It is functionally the same as the c version. But I will say, that
generally, it recommended when passing strings with have a size with
it, similar to other WIN32 functions that has string by reference
pointer with a size to copy to the pointer and the pointer is
allocated in the caller side with the function simply filling in.

But if you don't have control of the DLL, then you have to prototype
it the why it is with var status : pchar.

I'll be interested to see what you find out to get it right.

--
 
Mike said:
Forgot to point out, maybe it will matter by the compiler directive

{$H-}

may make a big difference. Try {$H+} as well. If I recall, it makes a
short STRING into a HUGE string. A short again, is the zero index byte
length format but its limite to 255 characters. The {$H+} makes all
those string type into C like pointer strings.

--
Click to expand...

Andrius,

You might have figured it out by now, if you did, pass on the info :-)

I tried to figure out why I could not get basic delphi pascal DLL to
marshal correctly. But what I did was to make sure it worked as a C dll.

---------------- cut/paste to mydll.c ------------
// file: mydll.c
// compiled like so: cl mydll.c /LD /DLL

#include <stdio.h>
#include <windows.h>

__declspec( dllexport ) int __stdcall GetStatus(char *status)
{
strcpy(status,"success from mydll.dll");
return 1;
}
------------------- cut here ------------------------

This worked calling it from C applet, VB.NET, even a delphi applet

For VB.NET, the import just like I gave you, worked fine:

' import mydll.c
Declare Auto Function cdll_GetStatus Lib "mydll.dll"
(ByVal status As IntPtr) As Integer

' wrapper
Function GetStatus(ByRef status As String) As Integer
Dim h As IntPtr = Marshal.AllocHGlobal(255)
Dim res As Integer = cdll_GetStatus(h)
status = Marshal.PtrToStringAnsi(h)
Marshal.FreeHGlobal(h)
Return res
End Function

Well, a Delphi DLL should work the same:

// File : testpasdll.pas
{$H-,O-,A-}
Library testpasdll;

uses
sysutils,windows;

function GetStatus(var status : pchar): integer; stdcall;
begin
StrPlCopy(status,'success from pascal dll',255);
result := 1;
end;
//////////////////////////////////// EXPORT LIST
Exports
GetStatus index 1;
end.

Its been so long that I have worked with the finer details of delphi,
but I am sure it is related to getting to the mixed string stuff in
delphi similar to how VB6 had BSTR string and fixed strings mixing.

Bu I just have not figured why the above does not marshal correctly.
It is functionally the same as the c version. But I will say, that
generally, it recommended when passing strings with have a size with
it, similar to other WIN32 functions that has string by reference
pointer with a size to copy to the pointer and the pointer is
allocated in the caller side with the function simply filling in.

But if you don't have control of the DLL, then you have to prototype
it the why it is with var status : pchar.

I'll be interested to see what you find out to get it right.

--
 
Hi,

Thanks for your trying to help.
The problem is, that this DLL with that function was made not by me, but
another programmer; I needed this function in order to improve my app
written in VB.NET, bay adding some new function. So, the author of DLL just
sent me the brief description of the function, and that's all.
After this weekend I'll try to connect with him and ask additional questions
about specifications for using it in VB.

If I find out smth I will write here.

Thanks again.

Andrius
 
Hi,

Thanks for your trying to help.
The problem is, that this DLL with that function was made not by me, but
another programmer; I needed this function in order to improve my app
written in VB.NET, bay adding some new function. So, the author of DLL just
sent me the brief description of the function, and that's all.
After this weekend I'll try to connect with him and ask additional questions
about specifications for using it in VB.

If I find out smth I will write here.

Thanks again.

Andrius
 
Hi Andrius,

I was able to finally get the Delphi DLL to import and marshall
correctly. Try this:

Declare Ansi Function GetStatus Lib "mydll.dll" _
(Byval user as string, _
byval pwd as string, _
ByRef status as String) as Boolean

The issue was the AUTO. Changing it to ANSI made it marshall correctly
without requiring wrapping IntPtr.

Now, to use it you MUST initialize the status string:

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)
writeline("- GetStatus() ==> [{0}] ",s)

Try it.

==
 
Hi Andrius,

I was able to finally get the Delphi DLL to import and marshall
correctly. Try this:

Declare Ansi Function GetStatus Lib "mydll.dll" _
(Byval user as string, _
byval pwd as string, _
ByRef status as String) as Boolean

The issue was the AUTO. Changing it to ANSI made it marshall correctly
without requiring wrapping IntPtr.

Now, to use it you MUST initialize the status string:

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)
writeline("- GetStatus() ==> [{0}] ",s)

Try it.

==
 
A followup Andrius <g>

The code below worked with .NET

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)

without allocating space, because as I understand it, in this the
DELPHI DLL I was using was just copying to a null terminated string
pointer marshaled by .NET

But I was leery with the initializing and not allocating space for it.

So I went back to one my C/C++ dll functions where I have server
functions that outputting string and here I use DLLImportAttribute.

Seeing how I can use Declare ANSI I changed my .NET signature to use
Declare ANSI to see if that worked:

Declare Ansi Function GetConnectedServer Lib "wcsrv2.dll" _
(ByVal name As string, _
ByVal namesize As Integer) As Boolean

Here, I needed to allocate the string space in this wrapper function:

Function GetConnectedServer() As String
const namesize as integer = 255
dim name as string = space(namesize)
if GetConnectedServer(name,namesize) then
Dim wsp() As Char = {Chr(32), Chr(0)}
return name.tostring.trim(wsp)
end if
return ""
End Function

So I would not trust pchar string without allocating space.

Finally, I had seen many references to StringBuilder being useful for
marshalling and that works very nicely:

Declare Ansi Function GetConnectedServer Lib "wcsrv2.dll" _
(ByVal name As StringBuilder, _
ByVal namesize As Integer) As Boolean

Function GetConnectedServer() As String
const namesize as integer = 255
Dim name As New StringBuilder(namesize)
if GetConnectedServer(name,namesize) then
return name.tostring
end if
return ""
End Function

Probably using StringBuilder for your GetStatus() makes sense/

--
Hi Andrius,

I was able to finally get the Delphi DLL to import and marshall
correctly. Try this:

Declare Ansi Function GetStatus Lib "mydll.dll" _
(Byval user as string, _
byval pwd as string, _
ByRef status as String) as Boolean

The issue was the AUTO. Changing it to ANSI made it marshall correctly
without requiring wrapping IntPtr.

Now, to use it you MUST initialize the status string:

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)
writeline("- GetStatus() ==> [{0}] ",s)

Try it.

==

Hi,

Thanks for your trying to help.
The problem is, that this DLL with that function was made not by me,
but another programmer; I needed this function in order to improve my
app written in VB.NET, bay adding some new function. So, the author of
DLL just sent me the brief description of the function, and that's all.
After this weekend I'll try to connect with him and ask additional
questions about specifications for using it in VB.

If I find out smth I will write here.

Thanks again.

Andrius
Click to expand...
Click to expand...
 
A followup Andrius <g>

The code below worked with .NET

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)

without allocating space, because as I understand it, in this the
DELPHI DLL I was using was just copying to a null terminated string
pointer marshaled by .NET

But I was leery with the initializing and not allocating space for it.

So I went back to one my C/C++ dll functions where I have server
functions that outputting string and here I use DLLImportAttribute.

Seeing how I can use Declare ANSI I changed my .NET signature to use
Declare ANSI to see if that worked:

Declare Ansi Function GetConnectedServer Lib "wcsrv2.dll" _
(ByVal name As string, _
ByVal namesize As Integer) As Boolean

Here, I needed to allocate the string space in this wrapper function:

Function GetConnectedServer() As String
const namesize as integer = 255
dim name as string = space(namesize)
if GetConnectedServer(name,namesize) then
Dim wsp() As Char = {Chr(32), Chr(0)}
return name.tostring.trim(wsp)
end if
return ""
End Function

So I would not trust pchar string without allocating space.

Finally, I had seen many references to StringBuilder being useful for
marshalling and that works very nicely:

Declare Ansi Function GetConnectedServer Lib "wcsrv2.dll" _
(ByVal name As StringBuilder, _
ByVal namesize As Integer) As Boolean

Function GetConnectedServer() As String
const namesize as integer = 255
Dim name As New StringBuilder(namesize)
if GetConnectedServer(name,namesize) then
return name.tostring
end if
return ""
End Function

Probably using StringBuilder for your GetStatus() makes sense/

--
Hi Andrius,

I was able to finally get the Delphi DLL to import and marshall
correctly. Try this:

Declare Ansi Function GetStatus Lib "mydll.dll" _
(Byval user as string, _
byval pwd as string, _
ByRef status as String) as Boolean

The issue was the AUTO. Changing it to ANSI made it marshall correctly
without requiring wrapping IntPtr.

Now, to use it you MUST initialize the status string:

dim s as string = "" ' <<--- MUST INITIALIZE
GetStatus("mike","xxxx", s)
writeline("- GetStatus() ==> [{0}] ",s)

Try it.

==

Hi,

Thanks for your trying to help.
The problem is, that this DLL with that function was made not by me,
but another programmer; I needed this function in order to improve my
app written in VB.NET, bay adding some new function. So, the author of
DLL just sent me the brief description of the function, and that's all.
After this weekend I'll try to connect with him and ask additional
questions about specifications for using it in VB.

If I find out smth I will write here.

Thanks again.

Andrius
Click to expand...
Click to expand...
 
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