FREADDIR
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Syntax
I16V UDS I16V I32V
FREADDIR (filenum, buffer, length, lrecnum);
Parameters
- filenum
16-bit signed integer by value (required)
Passes the file number of the file to be read.
- buffer
user-defined structure (required)
Returns the record that was read. This structure should be large enough to hold all of the information to be transferred.
- length
16-bit signed integer by value (required)
Passes the number of half words or bytes to be transferred. If this value is positive, it signifies half words; if negative, bytes. Zero signifies that no transfer occurs. If length is less than the size of the logical record, only the first length half words or bytes are read from the record.
If length is larger than the size of the logical record and the multirecord aoption in FOPEN/HPFOPEN was not specified, the transfer is limited to the length of the logical record. If the multirecord aoption in FOPEN/HPFOPEN is specified, the remaining half words or bytes specified in length are read from the next records.
- lrecnum
32-bit signed integer by value (required)
The relative number, in the file, of the logical record or block number for the NOBUF files to be read. A value of zero indicates the first logical record.
(KSAM) Indicates the relative chronological record number where the the chronological pointer is positioned. Chronological record numbering for fixed-length records starts with 0 or 1, as specified when the file was built.
Operation Notes
This intrinsic is different than the FREAD intrinsic. The FREAD intrinsic reads only the record already pointed to by the logical record pointer. Issue the FREADDIR intrinsic only for disk files composed of fixed-length or undefined-length records. If RIO access is used, FREADDIR inputs the specified logical record. If the record is inactive, the contents of the inactive record are transmitted and CCE (2) is returned; there is no indication of the block containing some inactive records. (FCHECK returns a nonzero error number to distinguish active and inactive records.) If an RIO file is accessed using the non-RIO method (NOBUF), FREADDIR inputs the specified block. After the FREADDIR intrinsic is executed, the logical record pointer is set to the beginning of the next logical record, or the first logical record of the next block for NOBUF files. It is possible to skip portions of records inadvertently, if the multirecord aoption of FOPEN/HPFOPEN is set and the length parameter specified is greater than one logical record. For example, if all of record 11 and half of record 12 is read in a file, the logical record pointer is set to the beginning of record 13 after the FREADDIR intrinsic executes; the second half of record 12 is skipped. Byte stream files are applicable with FREADDIR intrinsic. The lrecnum parameter specifies a byte offset in the byte stream file, which is equivalent to a logical record number, since the record size is one byte. Not applicable to message files.
Condition Codes
| CCE (2) | Request granted. The information was read. |
| CCG (0) | Request denied. End-of-file was encountered. |
| CCL (1) | Request denied. The information was not read; an error occurred. |
Related Information
| Intrinsics | FREAD, FREADBACKWARD, FREADBYKEY, FREADC, FREADLABEL, FREADSEEK, FWRITEDIR |
| Manuals |
Accessing Files Programmer's Guide Using KSAM XL KSAM/3000 Reference Manual |
|
FREADC |
FREADLABEL |