IDataConvert::GetConversionSize

OLE DB Programmer's Reference

Calculates the size of the buffer needed by the destination data type to support a conversion.

HRESULT GetConversionSize (    DBTYPE       wSrcType,    DBTYPE       wDstType,    DBLENGTH *   pcbSrcLength,    DBLENGTH *   pcbDstLength,    void *       pSrc);

Parameters

wSrcType

[in]
The source type of the data.

wDstType

[in]
The destination type of the data.

pcbSrcLength

[in]
A pointer to the length of the source data, in bytes. This value can be a null pointer.

pcbDstLength

[out]
A pointer to memory in which to return the size of the destination buffer required for the conversion, in bytes.

pSrc

[in]
A pointer to the source data.

Return Code

S_OK

The method succeeded.

E_FAIL

A provider-specific error occurred.

E_INVALIDARG

pcbDstLength was a null pointer, or the information supplied by the consumer was insufficient to determine the appropriate buffer size.

pcbSrcLength was a null pointer, and the conversion size was requested for a conversion from a variable-length data type to DBTYPE_STR, DBTYPE_WSTR, DBTYPE_BSTR, or DBTYPE_VARIANT.

DB_E_UNSUPPORTEDCONVERSION

The requested conversion was not supported.

Comments

The size of a fixed-width destination type can be discovered by passing a null pointer in the pSrc parameter. For example, the width of wType can be determined by adding the following code:

pConvert->GetConversionSize(wType, wType, 0, &ulWidth, 0);

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