[英]Is it necessary to free the memory of strings in C++ received from C#?
I have the following exposed DLL functions in C++.我在 C++ 中有以下暴露的 DLL 函数。
// center_of_rotation_api.h
// CENTER_OF_ROTATION_API is a macro like __cdecl(dllexport) on Windows
CENTER_OF_ROTATION_API void SerializeMesh(Mesh * mesh, const char * path);
CENTER_OF_ROTATION_API const char * SerializationError(Mesh * mesh);
From C#, I use the following.从 C# 开始,我使用以下内容。
// dll is the name of the compiled dll
[DllImport(dll)]
public static extern void SerializeMesh(IntPtr mesh, string path);
[DllImport(dll)]
public static extern IntPtr SerializationError(IntPtr mesh);
The IntPtr
returned by SerializationError
is allocated using new
in C++. SerializationError
返回的IntPtr
使用 C++ 中的new
分配。 So I have another DLL exported function that frees the pointer when called by C#.所以我有另一个 DLL 导出的 function 在被 C# 调用时释放指针。
My question is, do I need to free the memory of the const char * path
in the argument of SerializeMesh
in C++?我的问题是,我是否需要在 C++ 的
SerializeMesh
参数中释放const char * path
的 memory?
No, the C# marshaler will take care of this for you.不,C# 封送器会为您解决这个问题。 The
char*
will be valid during the lifetime of the PInvoke call. char*
将在 PInvoke 调用的生命周期内有效。 If your C++ code expects to own the char*
, you should make a copy in SerializeMesh
.如果您的 C++ 代码期望拥有
char*
,您应该在SerializeMesh
中制作一份副本。
Here is a primer on string marshaling. 这是字符串编组的入门。 If you really need to use a
const char*
, you might need to set the MarshalAsAttribute to UnmanagedType.LPStr
.如果您确实需要使用
const char*
,则可能需要将MarshalAsAttribute设置为UnmanagedType.LPStr
。 See here for more information on string marshaling behavior.有关字符串编组行为的更多信息,请参见此处。
Here is another useful reference if you want to dig even deeper.如果您想更深入地挖掘, 这是另一个有用的参考。
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