Action

Function: Returns the position of the next Byte to be read or written

Statement: Sets the position of the next Byte to be read or written

 

 

Syntax

Function: NextReadWrite = SEEK (#bFileNumber)

Statement: SEEk #bFileNumber, NewPos

 

 

Remarks

 

This function returns the position of the next Byte to be read or written. If an error occurs, 0 is returned. Check DOS-Error in variable gbDOSError.

 

The statement also returns an error in the gbDOSerror variable in the event that an error occurs.

You can for example not set the file position behinds the file size.

 

In VB the file is filled with 0 bytes when you set the file pointer behind the size of the file. For embedded systems this does not seem a good idea.

 

 

Seek and Loc seems to do the same function, but take care : the seek function will return the position of the next read/write, while the Loc function returns the position of the last read/write. You may say that Seek = Loc+1.

 

 

In QB/VB you can use seek to make the file bigger. When a file is 100 bytes long, setting the file pointer to 200 will increase the file with 0 bytes. By design this is not the case in AVR-DOS.

 

 

 

See also

INITFILESYSTEM , OPEN , CLOSE, FLUSH , PRINT, LINE INPUT, LOC, LOF , EOF , FREEFILE , FILEATTR , BSAVE , BLOAD , KILL , DISKFREE , DISKSIZE , GET , PUT , FILEDATE , FILETIME , FILEDATETIME , DIR , FILELEN , WRITE , INPUT

 

 

 

ASM

 

 

 

 

Partial Example

Open "test.biN"for Binary As #2

Put#2 , B                                                   ' write a byte

Put#2 , W                                                   ' write a word

Put#2 , L                                                   ' write a long

Ltemp = Loc(#2) + 1                                         ' get the position of the next byte

Print Ltemp ; " LOC"                                       ' store the location of the file pointer

Print Seek(#2) ; " = LOC+1"

Close #2

 

 

'now open the file again and write only the single

Open "test.bin" For Binary As #2

Seek#2 , Ltemp                                             ' set the filepointer

Sn = 1.23                                                   ' change the single value so we can check it better

Put #2 , Sn = 1                                             'specify the file position

Close #2