importing a c dll function into c#

Question

I am trying to use a function in C# from an unmanged C dll. I'm new to C# and am unsure if I'm doing this correctly. The function in C looks something like this:

unsigned short Function(unsigned short, unsigned long, unsigned long, unsigned short*);


[DllImport("cDLLfile.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
private static extern short Function(ushort a, UInt32 b, UInt32 c, IntPtr buffer);

The buffer is an array something like

ushort[] = new ushort[7];

I fill the array then try to pass it to Function and am getting a error. I know IntPtr is not right. What is the correct way to do this?

Seems to be a duplicate of http://stackoverflow.com/questions/289076/how-can-i-pass-a-pointer-to-an-array-using-p-invoke-in-c — Andrew T Finnell, Dec 27 '10 at 19:09

score 2 · Accepted Answer · answered Dec 27 '10 at 19:12

2

It should work with ushort[]

[DllImport("cDLLfile.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true) ]
private static extern short Function(ushort a, UInt32 b, UInt32 c, ushort[] buffer);

answered Dec 27 '10 at 19:12

Pablo Retyk

5,690
6
44
59

2

Avoid ExactSpelling, the C function is usually exported as _Function. CallingConvention is required, Cdecl. – Hans Passant Dec 27 '10 at 19:56

pstrjds · Answer 2 · 2010-12-27T20:25:57.307

0

Try this:

extern short Function(ushort a, UInt32 b, UInt32 c, ushort[] buffer)

edited Dec 27 '10 at 20:25

answered Dec 27 '10 at 19:10

pstrjds

16,840
6
52
61

No, don't try that. That will give a pointer-to-pointer (i.e. `ushort **`). – Jim Mischel Dec 27 '10 at 20:00

score 0 · Answer 3 · answered Dec 27 '10 at 20:20

0

Here you will find details and sample code on how to marshal arrays.

answered Dec 27 '10 at 20:20

Liviu Mandras

6,540
2
41
65

importing a c dll function into c#

3 Answers3