C# - 如何将对象转换为 IntPtr 并返回？
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原文地址: http://stackoverflow.com/questions/17339928/
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C# - How To Convert Object To IntPtr And Back?
提问by Bitterblue
I want to pass an object from managed code to a WinApi function as IntPtr. It will pass this object back to my callback function in managed code as IntPtr. It's not a structure, it's an instance of a class.
我想将托管代码中的对象作为IntPtr. 它会将这个对象作为IntPtr. 它不是一个结构，它是一个类的实例。
How do I convert objectto IntPtrand back ?
我如何转换object为IntPtr和返回？
采纳答案by Bitterblue
So if I want to pass a list to my callback function through WinApi I use GCHandle
因此，如果我想通过 WinApi 将列表传递给我的回调函数，我将使用GCHandle
// object to IntPtr (before calling WinApi):
List<string> list1 = new List<string>();
GCHandle handle1 = GCHandle.Alloc(list1);
IntPtr parameter = (IntPtr) handle1;
// call WinAPi and pass the parameter here
// then free the handle when not needed:
handle1.Free();
// back to object (in callback function):
GCHandle handle2 = (GCHandle) parameter;
List<string> list2 = (handle2.Target as List<string>);
list2.Add("hello world");
Thx to David Heffernan
感谢大卫·赫弗南
Edit:As noted in the comments, you need to free the handle after use. Also I used casting. It might be wise to use the static methods GCHandle.ToIntPtr(handle1)and GCHandle.FromIntPtr(parameter)like here. I haven't verified that.
编辑：如评论中所述，您需要在使用后释放手柄。我也使用了铸造。使用静态方法可能是明智的GCHandle.ToIntPtr(handle1)，GCHandle.FromIntPtr(parameter)就像这里。我没有验证过。
回答by Josh Gust
While the accepted answer is correct, I wanted to add a little bit to it.
虽然接受的答案是正确的，但我想补充一点。
I have grown fond of creating extensions for this so it reads: list1.ToIntPtr().
我越来越喜欢为此创建扩展，所以它写着：list1.ToIntPtr().
public static class ObjectHandleExtensions
{
public static IntPtr ToIntPtr(this object target)
{
return GCHandle.Alloc(target).ToIntPtr();
}
public static GCHandle ToGcHandle(this object target)
{
return GCHandle.Alloc(target);
}
public static IntPtr ToIntPtr(this GCHandle target)
{
return GCHandle.ToIntPtr(target);
}
}
Also, depending on how much of this you're doing, it might be nice to contain your list in an IDisposable.
此外，根据您所做的工作量，将您的列表包含在IDisposable.
public class GCHandleProvider : IDisposable
{
public GCHandleProvider(object target)
{
Handle = target.ToGcHandle();
}
public IntPtr Pointer => Handle.ToIntPtr();
public GCHandle Handle { get; }
private void ReleaseUnmanagedResources()
{
if (Handle.IsAllocated) Handle.Free();
}
public void Dispose()
{
ReleaseUnmanagedResources();
GC.SuppressFinalize(this);
}
~GCHandleProvider()
{
ReleaseUnmanagedResources();
}
}
And then you might consume it like this:
然后你可能会像这样消费它：
using (var handleProvider = new GCHandleProvider(myList))
{
var b = EnumChildWindows(hwndParent, CallBack, handleProvider.Pointer);
}
