c++ - 如何初始化SAFEARRAY从Scripting.Dictionary Keys方法返回的CComSafeArray

我正在使用COM库“Microsoft Scripting Runtime”(c:\ windows \ System32 \ scrrun.dll)中的Scripting.Dictionary。我正在使用import来获取包装纸，并且这些包装纸正在工作。添加一些项目后，我试图获取键列表，但我被卡住了。

我有办法我可以从Dictionary中获取键的SAFEARRAY，但是我想使用CComSafeArray中定义的<atlsafe.h>类，但是我找不到一个好的结构。当前，构造函数抛出ATL断言，抱怨vartype不匹配。诚然，新构建的CComSafeArray的CCCC的vartype为52428，十六进制形式，这看起来像是未初始化的内存。但是推断的类型也不正确，我期望safearray的vartype是字符串，但是断言代码给出的vartype 12是UI2。很奇怪。

无论如何，这对于熟悉这一点的人来说可能很容易。这是根据SO标准的最小，完整，可验证的示例(MCVE)控制台程序。

#include "stdafx.h"
#include <atlbase.h>
#include <atlsafe.h>

#import "c:\windows\System32\scrrun.dll" raw_interfaces_only,raw_native_types, named_guids, rename("DeleteFile", "_DeleteFile"), rename("MoveFile","_MoveFile"), rename("CopyFile", "_CopyFile"), rename("GetFreeSpace", "_GetFreeSpace")

int main()
{
    HRESULT hr = S_OK;

    CoInitialize(0);

    CComQIPtr<Scripting::IDictionary> dictColours;
    hr = dictColours.CoCreateInstance(__uuidof(Scripting::Dictionary));
    if (!SUCCEEDED(hr)) { return hr; }

    CComVariant varZero(0); //dummy value, only interested in keys

    hr = dictColours->Add(&variant_t(L"red"), &varZero);
    if (!SUCCEEDED(hr)) { return hr; }

    hr = dictColours->Add(&variant_t(L"green"), &varZero);
    if (!SUCCEEDED(hr)) { return hr; }

    hr = dictColours->Add(&variant_t(L"blue"), &varZero);
    if (!SUCCEEDED(hr)) { return hr; }

    long lColourCount(0);
    hr = dictColours->get_Count(&lColourCount);
    if (!SUCCEEDED(hr)) { return hr; }

    CComVariant varColoursKeys;
    hr = dictColours->Keys(&varColoursKeys);
    if (!SUCCEEDED(hr)) { return hr; }

    SAFEARRAY keys(*(varColoursKeys.parray));

    //fine up to this point

    CComSafeArray<VARIANT> varColours;

    /* The following code throws an error for the next (line) live, vt=52428 or hex CCCC which looks like uninitialised memory
       whilst GetType() returns 12 which is UI2 (and somehow I expected string type 8!)
    VARTYPE vt;
    HRESULT hRes = ::ATL::AtlSafeArrayGetActualVartype(const_cast<LPSAFEARRAY>(psaSrc), &vt);
    ATLENSURE_SUCCEEDED(hRes);
    ATLENSURE_THROW(vt == GetType(), E_INVALIDARG);
    */

    varColours = (keys);

    CoUninitialize();
    return 0;
}

最佳答案

更改此:

SAFEARRAY keys(*(varColoursKeys.parray));

对此:

SAFEARRAY* keys = varColoursKeys.parray;

(可选地，首先确保varColoursKeys.vt具有VT_ARRAY标志)

然后，您可以查询keys的vt:

hr = ::ATL::AtlSafeArrayGetActualVartype(keys, &vt);

注意varColours = keys将复制数组数据。如果这不是您真正想要的，则应从Detach()中对数组进行CComVariant(或直接使用VARIANT而不是CComVariant)，然后将其Attach()转换为CComSafeArray(然后可以使用CComSafeArray::GetType()方法)。

另外，在调用CoUninitialize()之前，需要确保所有COM包装器都超出范围并释放资源。

试试这个:

#include "stdafx.h"
#include <atlbase.h>
#include <atlsafe.h>

#import "c:\windows\System32\scrrun.dll" raw_interfaces_only,raw_native_types, named_guids, rename("DeleteFile", "_DeleteFile"), rename("MoveFile","_MoveFile"), rename("CopyFile", "_CopyFile"), rename("GetFreeSpace", "_GetFreeSpace")

HRESULT DoIt()
{
    CComQIPtr<Scripting::IDictionary> dictColours;
    hr = dictColours.CoCreateInstance(__uuidof(Scripting::Dictionary));
    if (FAILED(hr)) { return hr; }

    CComVariant varZero(0); //dummy value, only interested in keys

    hr = dictColours->Add(&variant_t(L"red"), &varZero);
    if (FAILED(hr)) { return hr; }

    hr = dictColours->Add(&variant_t(L"green"), &varZero);
    if (FAILED(hr)) { return hr; }

    hr = dictColours->Add(&variant_t(L"blue"), &varZero);
    if (FAILED(hr)) { return hr; }

    long lColourCount(0);
    hr = dictColours->get_Count(&lColourCount);
    if (FAILED(hr)) { return hr; }

    VARIANT varColoursKeys;
    hr = dictColours->Keys(&varColoursKeys);
    if (FAILED(hr)) { return hr; }

    CComSafeArray<VARIANT> varColours;
    varColours.Attach(varColoursKeys.parray);

    // use varColours as needed...

    VARTYPE vt = varColours.GetType();

    LONG lLower = varColours.GetLowerBound();
    LONG lUpper = varColours.GetUpperBound();
    for (LONG i = lLower; i <= lUpper; ++i)
    {
        VARIANT &v = varColours.GetAt(i);
        // use v.bstrVal as needed ...
    }

    //...

    return S_OK;
}

int main()
{
    HRESULT hr = CoInitialize(0);
    if (FAILED(hr)) { return hr; }

    hr = DoIt();

    CoUninitialize();
    return hr;
}

关于c++ - 如何初始化SAFEARRAY从Scripting.Dictionary Keys方法返回的CComSafeArray，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/49619401/