将 CComSafeArray 传递给需要 SAFEARRAY 的方法时，正确的语法是什么**

发布于 2024-07-12 00:46:50 字数 654 浏览 14 评论 0原文

这很可能有一个非常简单的答案，但我无法弄清楚。

我正在尝试重构一些如下所示的代码：

SAFEARRAY* psa;
long* count;
HRESULT hr = pSomeInterface->ListSomething(&psa, &count);
if (SUCCEEDED(hr))
{
    CComSafeArray<BSTR> sa;
    if (*count > 0)
    {
        sa.Attach(psa);
    }
}

// perform operations on sa
// allow CComSafeArray to destroy the object

return hr;

我想将代码更改为以下内容：

CComSafeArray<BSTR> sa;
long* count;
hr = pSomeInterface->ListSomething(&(sa.m_psa), &count);

if (SUCCEEDED(hr))
{
    // perform operations on sa
}

但是当我执行此操作时，sa 包含垃圾。发生了什么事以及为什么？正确的语法是什么？

原文

This most likely has a very simple answer, but I can't figure it out.

I'm trying to refactor some code that looks like this:

SAFEARRAY* psa;
long* count;
HRESULT hr = pSomeInterface->ListSomething(&psa, &count);
if (SUCCEEDED(hr))
{
    CComSafeArray<BSTR> sa;
    if (*count > 0)
    {
        sa.Attach(psa);
    }
}

// perform operations on sa
// allow CComSafeArray to destroy the object

return hr;

I would like to change the code to something like:

CComSafeArray<BSTR> sa;
long* count;
hr = pSomeInterface->ListSomething(&(sa.m_psa), &count);

if (SUCCEEDED(hr))
{
    // perform operations on sa
}

But when I execute this, sa contains garbage. What's happening and why? What is the correct syntax?

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还给你自由 2024-07-19 00:47:36

通过有效地绕过 CComSafeArray 并直接访问其内部 SAFEARRAY，您就破坏了使用 CComSafeArray 的全部意义。 CComSafeArray 定义了显式 LPSAFEARRAY 运算符，因此您应该能够执行此操作：

CComSafeArray<BSTR> sa;
long* count;
HRESULT hr = pSomeInterface->ListSomething(&sa, &count);
if (SUCCEEDED(hr))
{    
    // perform operations on sa
}

You're defeating the whole point of using CComSafeArray by effectively bypassing it and accessing its internal SAFEARRAY directly. CComSafeArray has an explicit LPSAFEARRAY operator defined, so you should be able to do this instead:

CComSafeArray<BSTR> sa;
long* count;
HRESULT hr = pSomeInterface->ListSomething(&sa, &count);
if (SUCCEEDED(hr))
{    
    // perform operations on sa
}

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听不够的曲调 2024-07-19 00:47:34

我在您的代码中没有看到任何此类问题。如果您可以分享 ListSomething(..) 方法的代码，那么我们也许能够找到一些东西，但是像这样的类似代码非常适合我。

void MyMethod(SAFEARRAY** pArray)
{
    int i = (*pArray)->cbElements;
    return;
}

CComSafeArray<BSTR> myArray;
myArray.Add(CComBSTR(_T("Test")));
myArray.Add(CComBSTR(_T("Best")));
myArray.Add(CComBSTR(_T("Rest")));
MyMethod(&(myArray.m_psa));

I don't see any such problem in your code. If you can share the code of ListSomething(..) method, then we might be able to find something but a similar code like this works perfectly with me.

void MyMethod(SAFEARRAY** pArray)
{
    int i = (*pArray)->cbElements;
    return;
}

CComSafeArray<BSTR> myArray;
myArray.Add(CComBSTR(_T("Test")));
myArray.Add(CComBSTR(_T("Best")));
myArray.Add(CComBSTR(_T("Rest")));
MyMethod(&(myArray.m_psa));

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