How to import a function which takes some parameters of native types?

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I have a native DLL written in C, which contains this function:

SomeFunction(int cmd, int param, unsigned char* data);

In my C# code on VS2005, how do I import this function via DllImport attribute? Note this function takes some parameters of native types.

Should I import this way:

C#

[DllImport("SomeNativeDll")]
public static extern int SomeFunction(int cmd, int param, ref byte data);

Posted 10-Nov-10 8:22am

Jun Du

Updated 10-Nov-10 8:33am

v3

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Nish Nishant · Accepted Answer · 2010-11-10T08:41:00

Solution 1

It really depends on what the parameter is used for. It seems to me that data is a byte buffer, so your P/Invoke signature should be:

C#

public static extern int SomeFunction(int cmd, int param, out byte[] data);

You may use ref instead of out, if the method expects you to pass an initialized array.

Posted 10-Nov-10 8:41am

Nish Nishant

Updated 10-Nov-10 8:42am

v3

Comments

Jun Du 12-Nov-10 10:09am

Thanks for the answer. Since my chunk of data is actually an input parameter to the call, I guess either "ref" keyword or none is good.

Nish Nishant 12-Nov-10 10:11am

Yes, that's right.