Sets the position for the next read/write operation within a file opened by using the Open statement.
Syntax
Seek [ # ] filenumber, position
The Seek statement syntax has these parts:
| Part | Description |
|---|---|
| filenumber | Required. Any valid file number. |
| position | Required. Number in the range 1 – 2,147,483,647, inclusive, that indicates where the next read/write operation should occur. |
Remarks
Record numbers specified in Get and Put statements override file positioning performed by Seek.
Performing a file-write operation after a Seek operation beyond the end of a file extends the file. If you attempt a Seek operation to a negative or zero position, an error occurs.
Example
This example uses the Seek statement to set the position for the next read or write within a file. This example assumes that TESTFILE is a file containing records of the user-defined type Record.
Type Record ' Define user-defined type.
ID As Integer
Name As String * 20
End TypeFor files opened in Random mode, Seek sets the next record.
Dim MyRecord As Record, MaxSize, RecordNumber ' Declare variables.
' Open file in random-file mode.
Open "TESTFILE" For Random As #1 Len = Len(MyRecord)
MaxSize = LOF(1) \ Len(MyRecord) ' Get number of records in file.
' The loop reads all records starting from the last.
For RecordNumber = MaxSize To 1 Step -1
Seek #1, RecordNumber ' Set position.
Get #1, , MyRecord ' Read record.
Next RecordNumber
Close #1 ' Close file.For files opened in modes other than Random mode, Seek sets the byte position at which the next operation takes place. This example assumes that TESTFILE is a file containing a few lines of text.
Dim MaxSize, NextChar, MyChar
Open "TESTFILE" For Input As #1 ' Open file for input.
MaxSize = LOF(1) ' Get size of file in bytes.
' The loop reads all characters starting from the last.
For NextChar = MaxSize To 1 Step -1
Seek #1, NextChar ' Set position.
MyChar = Input(1, #1) ' Read character.
Next NextChar
Close #1 ' Close file.