CODEWITHSUNDEEP
c#cwinapihandle
losingsleeep
losingsleeep

Reputation: 1879

How to pass HANDLEs between C#.NET and C Win32 DLL?

I have a C#.NET application and an unmanaged C Win32 .DLL program. How can i pass HANDLEs between the two app? i mean i wanna set a HANDLE from C code to a output parameter that comes from C#, and again, pass the HANDLE from C# to another function in the DLL? I guess it is related to IntPtr, but i don't know what the C & C# code should be!

thanks.

Upvotes: 0

Views: 4339

Answers (3)

David Heffernan
David Heffernan

Reputation: 612964

HANDLE is defined as void*, i.e. something the size of a pointer. The equivalent in the managed world is IntPtr.

Upvotes: 0

John Källén
John Källén

Reputation: 7943

To call C code from C#, you can use the DllImportAttribute to indicate the parameter as IntPtr:

[DllImport("mydll.dll", EntryPoint="my_c_function")]
public static extern void my_c_function(IntPtr myHandle);

[DllImport("mydll.dll", EntryPoint="my_c_function_with_out_param")]
public static extern void my_c_function(out IntPtr returnedHandle);

Just make sure that your C functions look like this:

void my_c_function(HANDLE myHandle) 
{   
    // ....
}

void my_c_function_with_out_param(HANDLE * pReturnedHandle)
{
   // ....
   *pReturnedHandle = GenerateHandle();    
}

Upvotes: 3

Oleg
Oleg

Reputation: 798

Just cast it ti IntPtr type in C code.

Upvotes: 0

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