Seek

Returns or sets the read/write position within a file opened by using the Open statement.

Seek Function

Returns a Long specifying the current read/write position within an open file.

Syntax: Seek( filenumber )

filenumber

required Integer containing a valid file number.

Seek returns a value between 1 and 2,147,483,647 (2^31 − 1), inclusive.

Mode	Return value
Random	Number of the next record to be read or written.
Binary, Output, Append, Input	Byte position at which the next operation takes place. The first byte in a file is at position 1.

Seek Statement

Sets the position for the next read/write operation within an open file.

Syntax: Seek [ # ] filenumber, position

filenumber

required Any valid file number.

position

required Number in the range 1--2,147,483,647 indicating where the next read/write operation should occur.

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. Attempting a Seek to a negative or zero position causes an error.

Examples

This example assumes that TESTFILE contains records of the user-defined type Record.

Type Record    ' Define user-defined type.
    ID As Integer
    Name As String * 20
End Type

For files opened in Random mode, the Seek function returns the number of the next record.

Dim MyRecord As Record
Open "TESTFILE" For Random As #1 Len = Len(MyRecord)
Do While Not EOF(1)    ' Loop until end of file.
    Get #1, , MyRecord    ' Read next record.
    Debug.Print Seek(1)    ' Print record number.
Loop
Close #1    ' Close file.

The Seek statement can set the record position. This example reads records in reverse order.

Dim MyRecord As Record, MaxSize, RecordNumber
Open "TESTFILE" For Random As #1 Len = Len(MyRecord)
MaxSize = LOF(1) \ Len(MyRecord)    ' Get number of records in file.
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, Seek returns or sets the byte position.

Dim MyChar
Open "TESTFILE" For Input As #1    ' Open file for reading.
Do While Not EOF(1)    ' Loop until end of file.
    MyChar = Input(1, #1)    ' Read next character.
    Debug.Print Seek(1)    ' Print byte position.
Loop
Close #1    ' Close file.

See Also

• Loc function
• LOF function
• EOF function