的PInvoke和焦炭**

问题描述：

我是一个完整的noob当涉及到C / C ++和PInvoke的，所以请裸跟我来。

I am a complete noob when it comes to c/c++ and PInvoke, so please bare with me.

我得到这个组件从别人，我想在我的C＃应用程序使用。

I got this assembly from someone which I'd like to use in my c# application.

标题是这样的：

int __declspec(dllimport) s2o(WCHAR* filename, char** out, int* len);

我设法得到它部分的工作，使用：

I managed to get it partly working, using:

[DllImport("s2o.dll", EntryPoint = "?skn2obj@@YAHPA_WPAPADPAH@Z", CallingConvention = CallingConvention.Cdecl)]
public static extern int s2o(
    [MarshalAs(UnmanagedType.LPWStr)]
    string filename,
    ref char[] @out,
    ref int len
);

，然后调用它是这样的：

And then calling it like this:

char[] result = null;
int length = 0;
s2o("filepath", ref result, ref length);

这似乎部分工作，因为'长'实际上得到的值。不幸的是，结果保持空。

It seems to work partly, because 'length' actually gets a value. Unfortunatly, 'result' stays null.

我应该做的就是这个工作？

What should I do to get this working?

编辑：

好，我设法通过与一个IntPtr的取代的char []，然后调用Marshal.PtrToStringAnsi就像尼克建议工作：

Ok I managed to get to to work by replacing the char[] with a IntPtr and then calling 'Marshal.PtrToStringAnsi' like Nick suggested:

string result = Marshal.PtrToStringAnsi(ptr);

然而，在同样的答复意见的，因为我对内存使用有点担心。还有，在组件中没有其他的方法让我怎么能清楚的事情了？

However, because of the comments in that same answer I'm a little worried about memory usage. There are no other methods provided in the assembly so how can I clear things up?

谢谢！

答

有一个看的 Marshal.PtrToStringAnsi 方法。

或者是中心的说，在评论你的问题，的PtrToStringAuto可能更合适。

Or as Centro says in the comment to your question, PtrToStringAuto may be more appropriate.

将所有字符，直到达到第一从非托管ANSI空字符字符串到托管String，并扩大每个ANSI字符统一code。

Copies all characters up to the first null character from an unmanaged ANSI string to a managed String, and widens each ANSI character to Unicode.

另外请注意，你可能会负责释放从这个函数返回的内存。

Also note that you may be responsible for freeing the memory returned from this function.

的PInvoke和焦炭**

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