如何在 C# 中使用 p/invoke 传递指向数组的指针？
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How can I pass a pointer to an array using p/invoke in C#?
提问by Randy Sugianto 'Yuku'
Example C API signature:
C API 签名示例：
void Func(unsigned char* bytes);
void Func(unsigned char* bytes);
In C, when I want to pass a pointer to an array, I can do:
在 C 中，当我想传递一个指向数组的指针时，我可以这样做：
unsigned char* bytes = new unsigned char[1000];
Func(bytes); // call
How do I translate the above API to P/Invoke such that I can pass a pointer to C# byte array?
如何将上述 API 转换为 P/Invoke，以便我可以传递指向 C# 字节数组的指针？
采纳答案by asponge
The easiest way to pass an array of bytes is to declare the parameter in your import statement as a byte array.
传递字节数组的最简单方法是将导入语句中的参数声明为字节数组。
[DllImport EntryPoint="func" CharSet=CharSet.Auto, SetLastError=true]
public extern static void Func(byte[]);
byte[] ar = new byte[1000];
Func(ar);
You should also be able to declare the parameter as an IntPtr and Marshal the data manually.
您还应该能够将参数声明为 IntPtr 并手动封送数据。
[DllImport EntryPoint="func" CharSet=CharSet.Auto, SetLastError=true]
public extern static void Func(IntPtr p);
byte[] ar = new byte[1000];
IntPtr p = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(byte)) * ar.Length);
Marshal.Copy(ar, 0, p, ar.Length);
Func(p);
Marshal.FreeHGlobal(p);
回答by FlySwat
You can use unsafe code:
您可以使用不安全代码：
unsafe
{
fixed(byte* pByte = byteArray)
IntPtr intPtr = new IntPtr((void *) pByte);
Func(intPtr);
}
If you need to use safe code, you can use a few tricks:
如果你需要使用安全代码，你可以使用一些技巧：
IntPtr intPtr = Marshal.AllocHGlobal(Marshal.SizeOf(byteArray));
Marshal.Copy(byteArray, 0, intPtr, Marshal.SizeOf(byteArray));
Func(intPtr);
Marshal.FreeHGlobal(intPtr);
However, the safe code is going to be slow IMHO.
但是，恕我直言，安全代码会很慢。
回答by JaredPar
Here is the appropriate signature for the native function.
这是本机函数的适当签名。
[System.Runtime.InteropServices.DllImportAttribute("<Unknown>", EntryPoint="Func")]
public static extern void Func(System.IntPtr bytes) ;
