使用pInvoke将C样式的LPWSTR数组编组到托管字符串[](Marshalling C-style array of LPWSTR to managed string[] using pInvoke)

 我想调用一个非托管方法来分配内存，创建一个LPWSTR数组，并将其返回给托管代码。 我想避免输入/输出参数和编写代码来尽可能地管理内存和变量范围，所以我决定依赖于使用CoTaskMemAlloc并让marshaller在我之后自动清理。 
 
 这就是我所拥有的（MSDN上的ap / invoke教程方法的修改版本）： 
 
extern "C" DLL1_API LPWSTR *TestArrayOfStrings(_In_ int count)
{
    STRSAFE_LPWSTR temp = NULL;
    wchar_t * ppStrArray[10] = { NULL };
    const size_t alloc_size = sizeof(wchar_t *) * 10;

    for (int i = 0; i < 10; i++)
    {

        temp = (STRSAFE_LPWSTR)CoTaskMemAlloc(alloc_size);

        if (i % 2 == 0)
            StringCchCopy(temp, alloc_size, L"0123456789");
        else
            StringCchCopy(temp, alloc_size, L"9876543210");

        CoTaskMemFree(ppStrArray[i]);
        ppStrArray[i] = temp;
    }
    count = 10;

    return ppStrArray;
}
 
 在管理方面： 
 
[DllImport("Dll1.Windows.dll", CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0, ArraySubType = UnmanagedType.LPWStr)]
public static extern string[] TestArrayOfStrings(out int count);
 
 正如你所看到的，我已经尝试使用其他属性但是marshaller似乎并不喜欢它 - 我一直得到“无法编组'返回值'：无效的托管/非托管类型组合。” 我试图保持打字作为LPWSTR的数组，并希望避免SAFEARRAY ，其编组已被标记为过时。 

I'd like to call an unmanaged method that allocates memory, creates an array of LPWSTRs, and returns it to managed code. I'd like to avoid in/out parameters and writing code to manage memory and variable scopes as much as possible so I decided I would rely on using CoTaskMemAlloc and let the marshaller automagically clean up after me. 
 
Here's what I have (a modified version of a p/invoke tutorial method on MSDN):
 
extern "C" DLL1_API LPWSTR *TestArrayOfStrings(_In_ int count)
{
    STRSAFE_LPWSTR temp = NULL;
    wchar_t * ppStrArray[10] = { NULL };
    const size_t alloc_size = sizeof(wchar_t *) * 10;

    for (int i = 0; i < 10; i++)
    {

        temp = (STRSAFE_LPWSTR)CoTaskMemAlloc(alloc_size);

        if (i % 2 == 0)
            StringCchCopy(temp, alloc_size, L"0123456789");
        else
            StringCchCopy(temp, alloc_size, L"9876543210");

        CoTaskMemFree(ppStrArray[i]);
        ppStrArray[i] = temp;
    }
    count = 10;

    return ppStrArray;
}
 
and on the managed side:
 
[DllImport("Dll1.Windows.dll", CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0, ArraySubType = UnmanagedType.LPWStr)]
public static extern string[] TestArrayOfStrings(out int count);
 
As you can see I've tried to use additional attributes but the marshaller just doesn't seem to like it--I keep getting "Cannot marshal 'return value': Invalid managed/unmanaged type combination." I am trying to maintain typing as an array of LPWSTRs and would like to avoid SAFEARRAY, for which marshalling is marked obsolete.

原文：https://stackoverflow.com/questions/30019488