Read

Reads data from a device.

virtual HRESULT Read(char& ch, bool bFlush = true, long lTimeout = CUR_TIMEOUT) override;

virtual HRESULT Read(BYTE* pBuf, long cbDesired, long* pcbActual, bool bFlush = true, long lTimeout = CUR_TIMEOUT) override;

virtual HRESULT Read(SAFEARRAY** pBuf, long cbDesired, bool bFlush = true, long lTimeout = CUR_TIMEOUT) override;

Parameters

ch: [out] Single character read from the device.
pBuf: [out] Array of bytes read from the device.
cbDesired: [in] Number of elements (bytes) to read from the device.
pcbActual: [out] Actual number of elements (bytes) read from the device.
bFlush: [in] If true, the formatted I/O read buffer is flushed.
lTimeout: [in] I/O timeout value in milliseconds.

Return Value

Returns S_OK if successful, otherwise a failure HRESULT.

Remarks

The Read function reads raw bytes from the formatted I/O read buffer. If the bFlush parameter is true, then the contents of the I/O read buffer are flushed. Flushing the read buffer ensures no unintentional data remains in the buffer for subsequent reads.

Example

The following example demonstrates use of the Read function.

C++

Copy

// CoAcme4321.cpp
STDMETHODIMP Acme4321::IAcme4321_QueryData(SAFEARRAY** ppsaData)
{
  HRESULT hr = S_OK;

  // Read 1000 bytes.  Type of elements is automatically determined from the type of the ppsaData SAFEARRAY parameter
  hr = io.Read(ppsaData, 1000);

  return hr;
}

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