C# 带有数组的非托管导出
我正在使用RGiesecke DLLExport库生成一个可以从Delphi动态加载的C DLL。我有这样一种方法:C# 带有数组的非托管导出,c#,unmanaged,loadlibrary,C#,Unmanaged,Loadlibrary,我正在使用RGiesecke DLLExport库生成一个可以从Delphi动态加载的C DLL。我有这样一种方法: [DllExport("GetVals", CallingConvention = System.Runtime.InteropServices.CallingConvention.StdCall)] static void GetVals([In, Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] int[
[DllExport("GetVals", CallingConvention = System.Runtime.InteropServices.CallingConvention.StdCall)]
static void GetVals([In, Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] int[] valueList, int len)
{
valueList = new int[3];
int[] arrList = new int[] { 1, 2, 3 };
int idx = 0;
foreach (int s in arrList)
{
valueList[idx] = s;
idx++;
}
}
我希望能够从这个调用中返回一个数组,问题是我无法预先知道数组的大小,这只能在运行时确定
为了测试,我在C中也做了以下工作
IntPtr hLibrary = NativeWinAPI.LoadLibrary(DLLFileName);
IntPtr pointerToFunction1 = NativeWinAPI.GetProcAddress(hLibrary, "GetVals");
if (pointerToFunction1 != IntPtr.Zero)
{
GetVals getfunction = (GetVals)Marshal.GetDelegateForFunctionPointer(pointerToFunction, typeof(GetVals));
int[] valList= null;
int fCnt = 3;
getfunction(valList, fCnt);
if (valList != null)
{
}
}
尝试读取或写入受保护内存时出错,这是可以理解的,因为我没有在调用者上分配内存。在实际使用中,我不知道要返回的数组的大小,因此无法预先分配内存。为了把最基本的东西放在那里,我试图简单地从GetVals返回一个大小未知的数组 必须以不受GC影响的方式分配数组。 您可以使用Marshal.AllocHGlobal执行此操作:
[DllExport]
static void GetVals(out IntPtr unmanagedArray, out int length)
{
var valueList = new[]
{
1, 2, 3
};
length = valueList.Length;
unmanagedArray = Marshal.AllocHGlobal(valueList.Length * Marshal.SizeOf(typeof(int)));
Marshal.Copy(valueList, 0, unmanagedArray, length);
}
在Delphi端,您将获得指向第一个元素的指针和大小。
要读取它,您可以将指针数组大小增加-1倍,并将其放入列表或Delphi管理的数组中:
uses
SysUtils,
Windows;
procedure GetVals(out unmanagedArray : PInteger; out arraySize : Integer);
stdcall;
external 'YourCSharpLib';
function GetValsAsArray : TArray<integer>;
var
unmanagedArray, currentLocation : PInteger;
arraySize, index : Integer;
begin
GetVals(unmanagedArray, arraySize);
try
SetLength(result, arraySize);
if arraySize = 0 then
exit;
currentLocation := unmanagedArray;
for index := 0 to arraySize - 1 do
begin
result[index] := currentLocation^;
inc(currentLocation);
end;
finally
LocalFree(Cardinal(unmanagedArray));
end;
end;
var
valuesFromCSharp : TArray<integer>;
index : Integer;
begin
valuesFromCSharp := GetValsAsArray();
for index := low(valuesFromCSharp) to high(valuesFromCSharp) do
Writeln(valuesFromCSharp[index]);
end.
您必须以不受GC影响的方式分配数组。 您可以使用Marshal.AllocHGlobal执行此操作:
[DllExport]
static void GetVals(out IntPtr unmanagedArray, out int length)
{
var valueList = new[]
{
1, 2, 3
};
length = valueList.Length;
unmanagedArray = Marshal.AllocHGlobal(valueList.Length * Marshal.SizeOf(typeof(int)));
Marshal.Copy(valueList, 0, unmanagedArray, length);
}
在Delphi端,您将获得指向第一个元素的指针和大小。
要读取它,您可以将指针数组大小增加-1倍,并将其放入列表或Delphi管理的数组中:
uses
SysUtils,
Windows;
procedure GetVals(out unmanagedArray : PInteger; out arraySize : Integer);
stdcall;
external 'YourCSharpLib';
function GetValsAsArray : TArray<integer>;
var
unmanagedArray, currentLocation : PInteger;
arraySize, index : Integer;
begin
GetVals(unmanagedArray, arraySize);
try
SetLength(result, arraySize);
if arraySize = 0 then
exit;
currentLocation := unmanagedArray;
for index := 0 to arraySize - 1 do
begin
result[index] := currentLocation^;
inc(currentLocation);
end;
finally
LocalFree(Cardinal(unmanagedArray));
end;
end;
var
valuesFromCSharp : TArray<integer>;
index : Integer;
begin
valuesFromCSharp := GetValsAsArray();
for index := low(valuesFromCSharp) to high(valuesFromCSharp) do
Writeln(valuesFromCSharp[index]);
end.