BltDataMarkRecord


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TBLT_RETC TBLT_ENTRY BltDataMarkRecord(TBLT_DH *dhPtr,
                                       ULONG recNo,
                                       ULONG tagChar);


 dhPtr          IO:data file control structure
 recNo          I:number of record to remove
 tagChar        I:byte to set tag character

This routine marks a data record's tag byte (the first byte of the record) with the tagChar byte.

Data records are not physically removed when deleted. Instead, records are tagged, or marked, as being deleted and then later removed by using BltDataPack(). The first byte of each data record is reserved for this byte. (Your first field starts at the second byte of the data record.)

The standard markers for this are <space> (a blank, ASCII 32) and * (a star, ASCII 42). The space indicates that the record is not deleted, and a star indicates that the record is deleted (marked as deleted, that is).

Two C macros are included if explicit delete and undelete names are needed. Supply the dhPtr and recNo args, leaving the tagChar to be set by the macro.

 #define BltDataDeleteRecord(a,b)    BltDataMarkRecord(a,b,42)
 #define BltDataUndeleteRecord(a,b)  BltDataMarkRecord(a,b,32)
Since your program has control of the entire data record already, this routine is not necessary; you may just set the first byte of your record as you want. However, you must still reserve this first byte for this use.

Return: Non-zero indicates an error, otherwise the first byte of the record is set to tagChar.




All content Copyright © 1999 Cornel Huth. All rights reserved.