IDebugDocumentChecksum2::GetChecksumAndAlgorithmId

 

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擷取指定要使用的位元組數目上限的文件的總和檢查碼和演算法識別項。

語法

HRESULT GetChecksumAndAlgorithmId(   
   GUID  *pRetVal,  
   ULONG cMaxBytes,  
   BYTE  *pChecksum,  
   ULONG *pcNumBytes  
);  

public int GetChecksumAndAlgorithmId(   
   out Guid pRetVal,  
   uint     cMaxBytes,  
   out byte pChecksum,  
   out uint pcNumBytes  
);  

參數

pRetVal
[out]總和檢查碼演算法的唯一識別碼。

cMaxBytes
[in]要用於總和檢查碼的位元組數目上限。

pChecksum
[out]總和檢查碼值。

pcNumBytes
[out]實際使用總和檢查碼的位元組數目。

傳回值

如果成功，傳回S_OK; 否則傳回錯誤碼。

範例

下列範例會使用這個方法來取得總和檢查碼和文件的演算法。

HRESULT CDebugCodeContext::GetDocumentChecksumAndAlgorithmId(GUID *pguidAlgorithm, BYTE **ppChecksum, ULONG *pcNumBytes)  
{  
    HRESULT hRes = E_FAIL;  
  
    *ppChecksum = NULL;  
    *pcNumBytes = 0;  
  
    CComPtr<IDebugDocumentContext2> pDocContext;  
  
    hRes = this->GetDocumentContext(&pDocContext);  
  
    if ( HREVAL(S_OK, hRes) )  
    {  
        CComQIPtr<IDebugDocumentChecksum2> pDocChecksum(pDocContext);  
  
        if ( pDocChecksum != NULL )  
        {  
            // Figure out the size of the checksum buffer required  
            ULONG cNumBytes = 0;  
  
            hRes = pDocChecksum->GetChecksumAndAlgorithmId(pguidAlgorithm, 0, NULL, &cNumBytes);  
  
            if ( S_OK == hRes )  
            {  
                // check to see if we got back valid values  
                if ( cNumBytes && GUID_NULL != (*pguidAlgorithm) )  
                {  
                    // Alloc space for the checksum data  
                    BYTE *pChecksum = (BYTE*) CoTaskMemAlloc(cNumBytes);  
  
                    if ( pChecksum )  
                    {  
                        // Get the buffer containing the checksum info  
                        hRes = pDocChecksum->GetChecksumAndAlgorithmId(pguidAlgorithm, cNumBytes, pChecksum, &cNumBytes);  
  
                        if ( HREVAL(S_OK, hRes) )  
                        {  
                            *ppChecksum = pChecksum;  
                            *pcNumBytes = cNumBytes;  
                        }  
                        else  
                        {  
                            CoTaskMemFree(pChecksum);  
                        }  
                    }  
                    else  
                        hRes = E_OUTOFMEMORY;  
                }  
                else  
                    hRes = S_FALSE; // lang doesn't support checksums  
            }  
            else  
                hRes = S_FALSE; // failed to work out checksum info  
        }  
        else  
            hRes = S_FALSE; // SH doesn't support checksums  
    }  
  
    return ( hRes );  
}  

另請參閱

IDebugDocumentChecksum2