Invoke

[GTi]

I have some functions that I want to Invoke in my C# project:

int NumberOfServers (BOOL UseENUM, LPCSTR MachineName);
BOOL GetServerName (int index, LPSTR Buffer, int BufSize);

can be used by:
[DllImport("some.dll")]
private static extern int NumberOfServers(bool UseENUM,
[MarshalAs(UnmanagedType.LPStr)]string MachineName);

[DllImport("some.dll")]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPTStr)]string Buffer, int BufSize);

But GetServerName just returns blanks:
string serverName = "
";
GetOPCServerName(index, serverName, serverName.Length);
And this one I have no idea:
HANDLE Connect(LPCSTR MachineName, LPCSTR ServerName, BOOL
EnableDLLBuffering);
HANDLE AddGroup(HANDLE hConnect, LPCSTR Name, DWORD *pRate, float
*pDeadBand);

And this one:
BOOL EnableNotification(HANDLE hConnect, NOTIFYPROC lpCallback);

void CALLBACK EXPORT OPCUpdateCallback(HANDLE hGroup, HANDLE hItem,
VARIANT *pVar, FILETIME timestamp, DWORD quality)
I know I must use delegates, but all help is wanted here.

Anyone ?

[Nicholas Paldino [.NET/C# MVP]]

GTi,

Your declaration of GetServerName is wrong. You need to use a
StringBuilder as opposed to a string when you expect the string to be
written to, like so:

[DllImport("some.dll")]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder Buffer, int BufSize);

As for the rest:

[DllImport("some.dll")]
static extern IntPtr(
[MarshalAs(UnmanagedType.LPTStr)]
string MachineName,
[MarshalAs(UnmanagedType.LPTStr)]
string ServerName,
bool EnableDLLBuffering);

[DllImport("some.dll")]
static extern IntPtr(
IntPtr hConnect,
[MarshalAs(UnmanagedType.LPTStr)]
string Name,
[MarshalAs(UnmanagedType.U4)]
ref int pRate,
ref float pDeadBand);

delegate void OPCUpdateCallback(
IntPtr hGroup,
IntPtr hItem
ref object pVar,
FILETIME timestamp,
[MarshalAs(UnmanagedType.U4)]
int quality);

[DllImport("some.dll")]
static extern EnableNotification(IntPtr, OPCUpdateCallback lpCallback);

You can get the definition of FILETIME from http://www.pinvoke.net, or
if you are using .NET 2.0, you can use the one in the
System.Runtime.InteropServices.ComTypes namespace.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

And this one:
BOOL EnableNotification(HANDLE hConnect, NOTIFYPROC lpCallback);

void CALLBACK EXPORT OPCUpdateCallback(HANDLE hGroup, HANDLE hItem,
VARIANT *pVar, FILETIME timestamp, DWORD quality)
I know I must use delegates, but all help is wanted here.

"GTi" <tu****@gmail.com> wrote in message
news:11*********************@g49g2000cwa.googlegro ups.com...I have some functions that I want to Invoke in my C# project:

int NumberOfServers (BOOL UseENUM, LPCSTR MachineName);
BOOL GetServerName (int index, LPSTR Buffer, int BufSize);

can be used by:
[DllImport("some.dll")]
private static extern int NumberOfServers(bool UseENUM,
[MarshalAs(UnmanagedType.LPStr)]string MachineName);

[DllImport("some.dll")]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPTStr)]string Buffer, int BufSize);

But GetServerName just returns blanks:
string serverName = "
";
GetOPCServerName(index, serverName, serverName.Length);
And this one I have no idea:
HANDLE Connect(LPCSTR MachineName, LPCSTR ServerName, BOOL
EnableDLLBuffering);
HANDLE AddGroup(HANDLE hConnect, LPCSTR Name, DWORD *pRate, float
*pDeadBand);

And this one:
BOOL EnableNotification(HANDLE hConnect, NOTIFYPROC lpCallback);

void CALLBACK EXPORT OPCUpdateCallback(HANDLE hGroup, HANDLE hItem,
VARIANT *pVar, FILETIME timestamp, DWORD quality)
I know I must use delegates, but all help is wanted here.

Anyone ?

[GTi]

Ahhh tx Nicholas,
After some testing in the mean time I get this to work also:

private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.VBByRefStr)]ref string MachineName, int
BufSize);
Don't what VBByRefStr is (Visual Basic Type) ?

GTi

[GTi]

I get an runtime error (int the win32 dll) when using it with
StringBuilder:
[DllImport("some.dll")]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder Buffer, int BufSize);

public string ServerName(int index)
{
StringBuilder text = new StringBuilder("", 128);

try { GetServerName(index, text, text.MaxCapacity); }
catch (Exception e) { _lastError = e.Message; }
return (text.ToString());
}

Any idea why?

[Nicholas Paldino [.NET/C# MVP]]

GTI,

You should not be using ref string, rather, StringBuilder is what is
guaranteed to work. The fact that it works with ref string is not a
supported mechanism to do what you are trying to do, and could change in the
future.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"GTi" <tu****@gmail.com> wrote in message
news:11*********************@g47g2000cwa.googlegro ups.com...

Ahhh tx Nicholas,
After some testing in the mean time I get this to work also:

private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.VBByRefStr)]ref string MachineName, int
BufSize);
Don't what VBByRefStr is (Visual Basic Type) ?

GTi

[Nicholas Paldino [.NET/C# MVP]]

GTi,

It's not working because you are passing MaxCapacity in for your buffer
size. This value, when used with a StringBuilder as you created it, will be
0x7fffffff, which is a really big number.

You should pass in the capacity of the string, returned by the Capacity
property.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"GTi" <tu****@gmail.com> wrote in message
news:11**********************@z14g2000cwz.googlegr oups.com...

I get an runtime error (int the win32 dll) when using it with
StringBuilder:
[DllImport("some.dll")]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder Buffer, int BufSize);

public string ServerName(int index)
{
StringBuilder text = new StringBuilder("", 128);

try { GetServerName(index, text, text.MaxCapacity); }
catch (Exception e) { _lastError = e.Message; }
return (text.ToString());
}

Any idea why?

[GTi]

Thanks Nicholas,
I have changed it now to:

[DllImport("some.dll", EntryPoint = "GetServerName", CharSet =
CharSet.Ansi)]
private static extern bool GetServerName(int index, [MarshalAs(
UnmanagedType.LPTStr)] StringBuilder Buffer, int BufSize);

StringBuilder text = new StringBuilder(128);
try { GetServerName(index, text, text.Capacity); }
catch (Exception e) { lastError = e; }
return (text.ToString());

But now it just return ????????????? where the name shuld be. But the
length of the ???? string (looks like it) match the real names.

Any tips?

[Nicholas Paldino [.NET/C# MVP]]

GTi,

You should change your declaration to this (if you are sure that you are
using the Ansi character set:

[DllImport("some.dll", EntryPoint = "GetServerName", CharSet =
CharSet.Ansi)]
private static extern bool GetServerName(int index,
[MarshalAs(UnmanagedType.LPStr)] StringBuilder Buffer, int BufSize);

This should work.

--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"GTi" <tu****@gmail.com> wrote in message
news:11**********************@f14g2000cwb.googlegr oups.com...

Thanks Nicholas,
I have changed it now to:

[DllImport("some.dll", EntryPoint = "GetServerName", CharSet =
CharSet.Ansi)]
private static extern bool GetServerName(int index, [MarshalAs(
UnmanagedType.LPTStr)] StringBuilder Buffer, int BufSize);

StringBuilder text = new StringBuilder(128);
try { GetServerName(index, text, text.Capacity); }
catch (Exception e) { lastError = e; }
return (text.ToString());

But now it just return ????????????? where the name shuld be. But the
length of the ???? string (looks like it) match the real names.

Any tips?

[GTi]

Nicholas,
Was using
MarshalAs(UnmanagedType.LPTStr)
changed it to:
MarshalAs(UnmanagedType.LPStr)

and voila !
You are my hero !

GTi

[GTi]

OK - I don't remeber it now - I give up.
Simple question:

How can I referer to FILETIME to the
System.Runtime.InteropServices.ComTypes namespace instead of the
System.Runtime.InteropServices ?

delegate void OPCUpdateCallback(IntPtr hGroup, IntPtr hItem, ref object
pVar, FILETIME timestamp, [MarshalAs(UnmanagedType.U4)]int quality);
Gives this error:
'FILETIME' is an ambiguous reference between
'System.Runtime.InteropServices.FILETIME' and
'System.Runtime.InteropServices.ComTypes.FILETIME'

But I can't remember what the syntax is to referer to another
namespace:
System.Runtime.InteropServices.ComTypes.FILETIME timespamp
does not work at all....

[GTi]

I solved it (rare bug)

My name space name is:
namespace MyLib.System

So trying to spesify the correct type using:
System.Runtime.InteropServices.ComTypes.FILETIME timestamp
gives me an error saying that Runtime was unknown..

Renaming my namespace to:
namespace MyLib.Lib
solved the problem....

(And I was almost giving up C# for this!)