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Seek Statement
Seek sets the position within an open file for the next read or write operation. Syntax
Seek [#]filenumber, position
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filenumber |
The number assigned in the Open statement to the file to be queried |
position |
An expression of type long representing the starting position of the next record number for a random read or write operation, or the byte offset from the beginning of the file |
Returns
Not applicable Usage
If you write to a file after seeking beyond the end of the file, the file's length is extended. Basic returns an error message if a Seek operation is attempted that specifies a negative or zero position. For files opened in Random mode, position is a record number; for other modes, position is a byte offset. Position is in the range 1 to 2,147,483,647. The first byte or record in the file is at position 1, the second is at position 2, and so on. Example
This example reads the contents of a sequential file line by line (to a carriage return) and displays the results. The second subprogram, CreateFile , creates the file C:\temp001 used by the main subprogram. (general) (declarations) Option Explicit Declare Sub CreateFile
Sub CreateFile Rem Put the numbers 10-100 into a file Dim x as Integer Open "c:\temp001" for Output as #1 For x = 10 to 100 step 10 Write #1, x Next x Close #1 End Sub
Sub Button_Click Dim testscore as String Dim x Dim y Dim newline Call CreateFile Open "c:\temp001" for Input as #1 x = 1 newline = Chr(10) msgtext = "The test scores are: " & newline Do Until x = Lof(1) Line Input #1, testscore x = x + 1 y = Seek(1) If y>Lof(1) then x = Lof(1) Else Seek 1,y End If msgtext = msgtext & newline & testscore Loop Close #1 Kill "c:\temp001" End Sub
Related Topics
Get Statement Open Statement Put Statement Seek Function
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