Hi all,

also,my problem is:

I have a DLL in C++
and I want link a function of this DLL in the programm language C#:

my problem is passing this string "COM1" from C# to the
type char *port .


---------------------------------------------------------------------
---C++ DLL---
extern "C" _declspec(dllexport) double getT_AV (long baud, char *port)
{
//port should point at "COM1" :char *port = "COM1"
...
}
---
---My C# Code---this code doesn't working
[DllImport("ChamberDriver.dll")]
public static extern double getT_AV(long baud,string port);

private void get_Temp_Click(object sender, System.EventArgs e)
{

long baud = 19200;
string port ="COM1"

double temp = getT_AV (baud,port);

Output.Text = temp.ToString();

}
---
----------------------------------------------------------------------
I hope my description is understandable ;)

thank you for Help !!!

Your problem is not with the string, but since you asked, here's the rule:
- If the DLL is going to change the content of the string (const char*), pass an System.Text.StringBuilder object
- If the DLL is not changing the content, (char*), pass a string.

Now, your real problem is with the "long", C/C++ long is 32-bit, .NET long is 64. So change C# decleration getT_AV(int baud, string ..etc) and you should be fine


: Hi all,
:
: also,my problem is:
:
: I have a DLL in C++
: and I want link a function of this DLL in the programm language C#:
:
: my problem is passing this string "COM1" from C# to the
: type char *port .
:
:
: ---------------------------------------------------------------------
: ---C++ DLL---
: extern "C" _declspec(dllexport) double getT_AV (long baud, char *port)
: {
: //port should point at "COM1" :char *port = "COM1"
: ...
: }
: ---
: ---My C# Code---this code doesn't working
: [DllImport("ChamberDriver.dll")]
: public static extern double getT_AV(long baud,string port);
:
: private void get_Temp_Click(object sender, System.EventArgs e)
: {
:
: long baud = 19200;
: string port ="COM1"
:
: double temp = getT_AV (baud,port);
:
: Output.Text = temp.ToString();
:
: }
: ---
: ----------------------------------------------------------------------
: I hope my description is understandable ;)
:
: thank you for Help !!!
: