问题
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public class Comarea
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1)]
public string status;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
public string operationName;
}
public static void StringToObject(string buffer, out Comarea comarea)
{
IntPtr pBuf = Marshal.StringToBSTR(buffer);
comarea = (Comarea)Marshal.PtrToStructure(pBuf, typeof(Comarea));
}
I can create object from single line of string but I can not do opposite of that.
How can I do that operation?
public static void ObjectToString(out string buffer, Comarea comarea)
{
???
}
It throws exception "Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
int size = Marshal.SizeOf(comarea);
IntPtr pBuf = Marshal.AllocHGlobal(size);
Marshal.StructureToPtr(comarea, pBuf, false);
buffer = Marshal.PtrToStringBSTR(pBuf); //Error
回答1:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public class Comarea
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1)]
public string status;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
public string operationName;
}
That is laid out as 6 adjacent 16 bit wchar_t
character elements. So, right off the bat,
public static void StringToObject(string buffer, out Comarea comarea)
{
IntPtr pBuf = Marshal.StringToBSTR(buffer);
comarea = (Comarea)Marshal.PtrToStructure(pBuf, typeof(Comarea));
}
is wrong. Beyond the fact that you leak a BSTR
, your struct is not a BSTR
.
You can implement it like this:
public static void StringToObject(string buffer, out Comarea comarea)
{
comarea.status = buffer.Substring(0, 1);
comarea.operationName = buffer.Substring(1, 5);
}
This is under the assumption that the six characters are the contained the the locations implied by the Substring
calls.
In the opposite direction you write:
public static void ObjectToString(out string buffer, Comarea comarea)
{
buffer = comarea.status + comarea.operationName;
}
Note that the struct definition must be wrong however
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1)]
public string status;
The marshaller always adds a null-terminator when using ByValTStr
. So with SizeConst
of 1
, status will always be marshaled as an empty string. Without actually seeing the unmanaged struct definition, I would not care to tell you how to fix this problem.
回答2:
That is how I solved my problem: I used char array and Marshal.PtrToStringAuto(pBuf, size)
public static void ObjectToString(out string buffer, Comarea comarea)
{
int size = 0;
IntPtr pBuf = IntPtr.Zero;
try
{
size = Marshal.SizeOf(comarea);
pBuf = Marshal.AllocHGlobal(size);
Marshal.StructureToPtr(comarea, pBuf, false);
buffer = Marshal.PtrToStringAuto(pBuf, size).Substring(0, size/2); // Answer
}
catch
{
throw;
}
finally
{
Marshal.FreeHGlobal(pBuf);
}
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct Comarea
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 1)]
private char[] status;
public string Status
{
get
{
return new string(status);
}
set
{
status = value.ToFixedCharArray(1);
}
}
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 5)]
private char[] operationName;
public string OperationName
{
get
{
return new string(operationName);
}
set
{
operationName = value.ToFixedCharArray(5);
}
}
}
public static class FormatterExtensions
{
[DebuggerStepThrough]
public static char[] ToFixedCharArray(this string inputString, int arrayLength)
{
char[] outputArray = new char[arrayLength];
char[] inputArray = inputString.ToSafeTrim().ToCharArray();
if (inputArray.Length == arrayLength)
{
return inputArray;
}
else
{
int i = 0;
while (i < arrayLength)
{
if (i < inputArray.Length)
{
outputArray[i] = inputArray[i];
}
else
{
break;
}
i++;
}
return outputArray;
}
}
}
It is so useful for IBM CICS communication(For Commarea)
来源:https://stackoverflow.com/questions/24697789/marshaling-structure-to-single-line-of-string