AdsGetRecordCRC

Computes a CRC checksum of the current record image.

Syntax

UNSIGNED32 AdsGetRecordCRC(ADSHANDLE hTable, UNSIGNED32 *pulCRC, UNSIGNED32 ulOptions);

Parameters

Parameter	Type	Description
`hTable`	`ADSHANDLE`	Handle of the table.
`pulCRC`	`UNSIGNED32*`	Receives the 32-bit CRC of the current record.
`ulOptions`	`UNSIGNED32`	Reserved; pass 0.

Return Value

AE_SUCCESS (0) on success. AE_NO_CURRENT_RECORD (5068) when the cursor is at BOF/EOF. AE_FUNCTION_NOT_AVAILABLE (5004) for remote tables.

Description

AdsGetRecordCRC returns a 32-bit checksum computed over the raw physical record image — the same bytes AdsGetRecord returns, including the leading deletion-flag byte. It uses the standard IEEE CRC-32 (reflected, polynomial 0xEDB88320).

The checksum is a fast way to detect whether a record has changed: read the CRC, do other work, read it again, and compare. Two records with identical field bytes produce the same CRC; any difference in the image yields a different value. The value is stable for a given record image but is not guaranteed to match the checksum any other ADS implementation computes.

This function is not available for remote tables.

Example

UNSIGNED32 ulBefore = 0, ulAfter = 0;

AdsGetRecordCRC(hTable, &ulBefore, 0);
// ... another process may update the row ...
AdsRefreshRecord(hTable);
AdsGetRecordCRC(hTable, &ulAfter, 0);

if (ulBefore != ulAfter)
    printf("record changed\n");