Important: The information in this document is obsolete and should not be used for new development.
SetFPos
You can use theSetFPos
function to set the position of the file mark before reading from or writing to an open file.
FUNCTION SetFPos (refNum: Integer; posMode: Integer; posOff: LongInt): OSErr;
refNum
- The file reference number of an open file.
posMode
- The positioning mode.
posOff
- The positioning offset.
DESCRIPTION
TheSetFPos
function sets the file mark of the specified file. TheposMode
parameter indicates how to position the mark; it must contain one of the following values:
CONST fsAtMark = 0; {at current mark} fsFromStart = 1; {set mark relative to beginning of file} fsFromLEOF = 2; {set mark relative to logical end-of-file} fsFromMark = 3; {set mark relative to current mark}If you specifyfsAtMark
, the mark is left wherever it's currently positioned, and theposOff
parameter is ignored. The next three constants let you position the mark relative to either the beginning of the file, the logical end-of-file, or the current mark. If you specify one of these three constants, you must also pass inposOff
a byte offset (either positive or negative) from the specified point. If you specifyfsFromLEOF
, the value inposOff
must be less than or equal to 0.RESULT CODES
noErr 0 No error ioErr -36 I/O error fnOpnErr -38 File not open eofErr -39 Logical end-of-file reached posErr -40 Attempt to position mark before start of file rfNumErr -51 Bad reference number