Higher Computing Software Design & Development

1. Sequential Files

2. Sequential Files
A sequential file is a collection of data items stored on a
backing storage device
Data items are stored in the file one after the other
To access a specific data item, we must first read through all
of the preceding data items (in sequence) until we reach the
data item we want
Sequential files use an end-of-file (EOF) marker to indicate
that the end of the file has been reached

3. Sequential Files

4. File Operations
There are a number of file operations which can be
performed on a sequential file. We are only interested in
the following:
Open
Create
Close
Read
Write
Delete

5. Open
Pseudocode:
OPEN Filename
LiveCode:

6. Create
Pseudocode:
CREATE Filename
LiveCode:
(opens the file, if it doesn’t exist then LiveCode will create
it)

7. Close
Pseudocode:
CLOSE Filename
LiveCode:

8. Read
Pseudocode:
OPEN Filename
REPEAT UNTIL EOF
READ next record from Filename into field / array
END REPEAT
CLOSE Filename

9. Read
LiveCode:

10. Write
Pseudocode:
OPEN Filename
REPEAT UNTIL EOF
WRITE next field/array element to Filename
END REPEAT
CLOSE Filename

11. Write
LiveCode:

12. Delete
Pseudocode:
DELETE Filename
LiveCode: