IEnumVARIANT::Next method (oaidl.h)

Makale
02/22/2024

Retrieves the specified items in the enumeration sequence.

Syntax

HRESULT Next(
  [in]  ULONG   celt,
  [out] VARIANT *rgVar,
  [out] ULONG   *pCeltFetched
);

Parameters

[in] celt

The number of elements to be retrieved

[out] rgVar

An array of at least size celt in which the elements are to be returned.

[out] pCeltFetched

The number of elements returned in rgVar, or NULL.

Return value

This method can return one of these values.

Return code	Description
S_OK	The number of elements returned is celt.
S_FALSE	The number of elements returned is less than celt.

Remarks

If fewer than the requested number of elements remain in the sequence, Next returns only the remaining elements. The actual number of elements is returned in pCeltFetched, unless it is null.

Examples

The following code implements IEnumVariant::Next. A complete example implementation of the IEnumVariant interface is available in the COM Fundamentals Lines sample (Enumvar.cpp).

STDMETHODIMP
CEnumVariant::Next(ULONG cElements, VARIANT * pvar, ULONG * pcElementFetched)
{
   HRESULT hr;
   ULONG l;
   long l1;
   ULONG l2;

   if (pcElementFetched != NULL)
      *pcElementFetched = 0;

   if (pvar == NULL)
      return E_INVALIDARG;

   for (l=0; l<cElements; l++)
      VariantInit(&pvar[l]);

   // Retrieve the next cElements elements.
   // m_lLBound+m_cElements = # of elements in the m_psa collection.

   for (l1=m_lCurrent, l2=0; l1<(long)(m_lLBound+m_cElements) &&
      l2<cElements; l1++, l2++)
   {
      hr = SafeArrayGetElement(m_psa, &l1, &pvar[l2]); 
      if (FAILED(hr))
         goto error; 
   }
   // Set count of elements retrieved.
   if (pcElementFetched != NULL)
      *pcElementFetched = l2;
   m_lCurrent = l1;

   return  (l2 < cElements) ? S_FALSE : NOERROR;

error:
   for (l=0; l<cElements; l++)
      VariantClear(&pvar[l]);
   return hr;
}

Requirements

Requirement	Value
Target Platform	Windows
Header	oaidl.h

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