使 C#.NET 中的 IntPtr 指向字符串值
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make IntPtr in C#.NET point to string value
提问by Saher Ahwal
I am using a class which has StringHandlefield which is an IntPtrvalue that represents a
LPCWSTRin C++.
我正在使用一个具有StringHandle字段的类，该字段是在 C++IntPtr中表示 a的值
LPCWSTR。
internal IntPtr StringHandle; // LPCWSTR
say now that I have a String: string x = "abcdefg"
现在说我有一个字符串： string x = "abcdefg"
How can I use the String handle to point to the beginning of the String so that it is like C++ LPCWSTR ?
如何使用 String 句柄指向 String 的开头，使其类似于 C++ LPCWSTR ？
采纳答案by Eren Ers?nmez
You need to copy the string to the unmanaged memory first and then get the IntPtrfrom that location. You can do so like:
您需要先将字符串复制到非托管内存，然后IntPtr从该位置获取。你可以这样做：
IntPtr strPtr = Marshal.StringToHGlobalUni(x);
also, you need to make sure to free the unmanaged memory:
此外，您需要确保释放非托管内存：
Marshal.FreeHGlobal(strPtr);
it's best to do all this in a try/finally.
最好在尝试/最后完成所有这些。
回答by CodingGorilla
回答by Hans Passant
Managed strings movein memory when the garbage collector compacts the heap. So they don't have a stable address and can't directly be cast to a LPCWSTR. You'll need to either pin the string with GCHandle.Alloc() to use GCHandle.AddrOfPinnedObject or copy it into unmanaged memory with Marshal.StringToHGlobalUni().
当垃圾收集器压缩堆时，托管字符串在内存中移动。所以他们没有一个稳定的地址，也不能直接转换成 LPCWSTR。您需要使用 GCHandle.Alloc() 固定字符串以使用 GCHandle.AddrOfPinnedObject 或使用 Marshal.StringToHGlobalUni() 将其复制到非托管内存中。
Strongly prefer copying if the address needs to be stable for a while.
如果地址需要稳定一段时间，强烈建议复制。
