SEEK (function): Difference between revisions
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=== Notes === | === Notes === | ||
* Don't confuse the | * Don't confuse the [[LOC]] position with the [[SEEK (function)|SEEK]] position !! | ||
** '''LOC''' is the {{Text|last|red}} read or written byte or record prosition. | |||
** '''SEEK''' is the byte or record prosition to read or write {{Text|next|red}}. | ** '''SEEK''' is the byte or record prosition to read or write {{Text|next|red}}. | ||
{{PageExamples}} | {{PageExamples}} | ||
;Example:Demonstrate the difference between | ;Example:Demonstrate the difference between '''LOC''' and '''SEEK''' positions in a file. | ||
{{CodeStart}} | {{CodeStart}} | ||
OPEN "readme.md" FOR BINARY AS #1 | OPEN "readme.md" FOR BINARY AS #1 |
Latest revision as of 00:10, 25 February 2023
The SEEK function returns the byte or record position in a file, which is read or written next.
Syntax
- byte = SEEK(filenumber&)
Parameters
- filenumber& is the number of an OPEN file in any mode.
- In RANDOM files SEEK returns the record position to read or write.
- In BINARY or sequencial files SEEK returns the byte position to read or write (first byte = 1).
- Since the first file position is 1 it may require adding one to an offset value when documentation uses that position as 0.
- Devices that do not support SEEK (SCRN, CONS, KBRD, COMn and LPTn) return 0.
Notes
- Don't confuse the LOC position with the SEEK position !!
- LOC is the last read or written byte or record prosition.
- SEEK is the byte or record prosition to read or write next.
Examples
- Example
- Demonstrate the difference between LOC and SEEK positions in a file.
OPEN "readme.md" FOR BINARY AS #1 PRINT LOC(1) 'LOC returns 0, as we didn't read something yet PRINT SEEK(1) 'SEEK otherwise returns 1, as it's the first byte to read GET #1, , a& 'now let's read a LONG (4 bytes) PRINT LOC(1) 'now LOC returns 4, the last read byte PRINT SEEK(1) 'and SEEK returns 5 now, the next byte to read CLOSE #1 END |
0 1 4 5 |
See also