Return a char array from C++ dll to C#

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Is there any way to create a function that returns a char array from c++ dll to a char array or string in c#?

Posted 6-Sep-10 6:14am

refael_berger0

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Toli Cuturicu 6-Sep-10 12:27pm

Yes. Where exactly is your problem. Show us what you tried so far.

Sandeep Mewara 6-Sep-10 13:19pm

Heard of managed-unmanaged code?

DaveyM69 9-Sep-10 3:25am

The answer is - it depends! Is the C++ function actually returning a char[] or a pointer to one? Where is the length of the array specified - in a parameter or a constant, or is it a null terminated one in which case it's really a string?
The easiest way for us to help you is if you give us the original C++ function declaration, from there it's normally pretty easy.
Alternatively, check out http://msdn.microsoft.com/en-us/magazine/cc164123.aspx, especially the 'Marshaling Text' section.

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Svetlin Panayotov · Answer 1 · 2010-09-06T08:16:00

In your C++ DLL:

C

__declspec(dllexport) TCHAR* __cdecl testString();

__declspec(dllexport) TCHAR* testString()
{
    return _T("Wheee!");
}

And to call it from your C# you need to do something like:

C#

class Program
{
[DllImport("MyDLL.dll", CallingConvention = CallingConvention.Cdecl)]
private static extern IntPtr testString();

void CallCppDLL()
{
IntPtr t = testString();
String result = Marshal.PtrToStringAuto(t);
}
}

I haven't done this in quite some time, so feel free to correct me :)

refael_berger0 · Answer 2 · 2010-09-08T14:46:00

Solution 2

It doesn't work because the returning address is of a local variable...
any other ideas?

Posted 8-Sep-10 14:46pm