Accessing text elements in a safearray

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问题：
ActiveX interfaces are accessible in C++ through the COM 'wrappers' as the doc
sample, AsdkMfcComSamps. When I used IAcadLayout::GetPlotDeviceNames(), it
returns a VARIANT type 8200. In this case, a string Array.

How do I access the elements in it? Attaching or creating SafeArrays of
COleSafeArray is successful and the upper and lower bounds are clear but I
cannot reach the data (strings).

解答：
This can be done by using some of the safe array global functions. The following
code sample demonstrates how to achieve this.

1. bool GetStringListFromSafeArray(SAFEARRAY *psaItemTexts, CStringList &strNodes)
   
2. {
   
3.    ASSERT (psaItemTexts);
   
4.    ULONG ulDims = SafeArrayGetDim(psaItemTexts);
   
5.    ASSERT (1 == ulDims);
   
6.    if (!psaItemTexts || 1 != ulDims)
   
7.             return false;
   
8. 
   
9.    // see if we are given more than one items
   
10.    long lLBound, lUBound; // note that dimension indices are one-based
    
11.    HRESULT hRes = SafeArrayGetUBound (psaItemTexts, 1, &lUBound);
    
12.    ASSERT (SUCCEEDED(hRes));
    
13.    if (FAILED (hRes))
    
14.             return false;
    
15. 
    
16.    hRes = SafeArrayGetLBound (psaItemTexts, 1, &lLBound);
    
17.    ASSERT (SUCCEEDED(hRes));
    
18.    if (FAILED (hRes))
    
19.             return false;
    
20. 
    
21.    // AcDcss the array
    
22.    BSTR *pabstrItemTexts = 0;
    
23.    hRes = ::SafeArrayAccessData (psaItemTexts, (void**)&pabstrItemTexts);
    
24.    ASSERT (SUCCEEDED (hRes));
    
25.    if (FAILED (hRes))
    
26.             return false;
    
27. 
    
28.    strNodes.RemoveAll ();
    
29.    USES_CONVERSION;
    
30.    for (long lName = lLBound; lName <= lUBound; lName ++)
    
31.             strNodes.AddTail (OLE2T (pabstrItemTexts [lName]));
    
32.    // release pointer returned by SafeArrayAcDcssData
    
33.    SafeArrayUnaccessData (psaItemTexts);
    
34. 
    
35.    return true;
    
36. }
    

bool GetStringListFromSafeArray(SAFEARRAY *psaItemTexts, CStringList &strNodes)<br /> {<br />    ASSERT (psaItemTexts);<br />    ULONG ulDims = SafeArrayGetDim(psaItemTexts);<br />    ASSERT (1 == ulDims);<br />    if (!psaItemTexts || 1 != ulDims)<br />             return false;<br /> <br />    // see if we are given more than one items<br />    long lLBound, lUBound; // note that dimension indices are one-based<br />    HRESULT hRes = SafeArrayGetUBound (psaItemTexts, 1, &lUBound);<br />    ASSERT (SUCCEEDED(hRes));<br />    if (FAILED (hRes))<br />             return false;<br /> <br />    hRes = SafeArrayGetLBound (psaItemTexts, 1, &lLBound);<br />    ASSERT (SUCCEEDED(hRes));<br />    if (FAILED (hRes))<br />             return false;<br /> <br />    // AcDcss the array<br />    BSTR *pabstrItemTexts = 0;<br />    hRes = ::SafeArrayAccessData (psaItemTexts, (void**)&pabstrItemTexts);<br />    ASSERT (SUCCEEDED (hRes));<br />    if (FAILED (hRes))<br />             return false;<br /> <br />    strNodes.RemoveAll ();<br />    USES_CONVERSION;<br />    for (long lName = lLBound; lName <= lUBound; lName ++)<br />             strNodes.AddTail (OLE2T (pabstrItemTexts [lName]));<br />    // release pointer returned by SafeArrayAcDcssData<br />    SafeArrayUnaccessData (psaItemTexts);<br /> <br />    return true;<br /> }<br />