FairCom ISAM for C

PreviousInVSet

Read the previous variable-length data record in the set defined by target.

Short Name

PRVVSET()

Type

ISAM function

Declaration

COUNT PreviousInVSet(FILNO filno, pVOID recptr, pVRLEN plen)

Description

In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering

PreviousInVSet() is identical to it’s fixed-length counterpart, PreviousInSet(), except that it reads the previous variable-length data record in the set defined by target and siglen. If successful, this record becomes the current ISAM record for the associated data file.

plen acts as both an input and output parameter:

On input, plen contains the length of the output buffer.
On output, the contents of plen is the actual data-record length. If the length of the output buffer is less than the actual record length, a partial read is performed. If an error occurs, plen is unspecified.

Read the function description for PreviousInSet() for additional important information.

Return

Value	Symbolic Constant	Explanation
0	NO_ERROR	Successful retrieval of current ISAM record.
633	NPLN_ERR	plen is NULL.
634	NLEN_ERR	plen is negative on input.

See c-tree Error Codes for a complete listing of valid c-tree error values.