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FairCom ISAM for C

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NextInSet

Read the next data record in the set defined by target.

Short Name

NXTSET()

Type

ISAM function

Declaration

COUNT NextInSet(FILNO keyno, pVOID recptr)

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

NextInSet() reads the next data record in the set of data records whose keys match the set created by an earlier set function call. If successful, this record becomes the current ISAM record for the associated data file. If an error occurs or no key value matches the target, the current ISAM record is not updated, and no key value set is defined.

If the data file has variable-length records, only the fixed-length portion, defined by dreclen in the original call to CreateIFile(), is actually read into the buffer pointed to by recptr. If you wish to read the entire variable-length record into the same or a different buffer, issue a call to ReReadVRecord() after the call to NextInSet(). Note that ReReadVRecord() requires the size of the buffer area so that it can check if sufficient space is available.

Notice that you do not directly identify the data file number involved. The ISAM parameter file described in c-tree Error Codes of the c-tree Programmer’s Reference Guide contains the correspondence between the index file number and the associated data file.

Return

Value

Symbolic Constant

Explanation

0

NO_ERROR

Successful retrieval of current ISAM record.

33

DNUL_ERR

recptr is NULL. No data file read performed.

42

DLOK_ERR

Could not get lock on data record. No data file read performed.

100

ICUR_ERR

No current ISAM record.

101

INOT_ERR

No active entries.

118

SKEY_ERR

Either FirstInSet() has not been called or the last call to FirstInSet() was not for index number keyno.

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

Example

FILNO keyfil;

TEXT target[24],recbuf[320];


printf("\nEnter set value:");

scanf("%23s",target);

FirstInSet(keyfil,target,recbuf,strlen(target));

while (isam_err == NO_ERROR) {

process_data();

NextInSet(keyfil,recbuf);

}

Limitations

No check is made to determine if recptr points to a region sufficiently large to accept a data record. If the area is too small, either code or data will be clobbered.

See also

FirstInSet(), PreviousInSet(), LastInSet(), PositionSet(), ChangeSet(), CreateIFile(), ReReadVRecord(), TransformKey()

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