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Inside Macintosh: Files /
Chapter 1 - Introduction to File Management / File Management Reference
File Access Routines / Manipulating the End-of-File


You can use the SetEOF function to set the logical end-of-file of an open file.

FUNCTION SetEOF (refNum: Integer; logEOF: LongInt): OSErr;
The file reference number of an open file.
The logical end-of-file.
The SetEOF function sets the logical end-of-file of the specified file. If you attempt to set the logical end-of-file beyond the physical end-of-file, the physical end-of-file is set 1 byte beyond the end of the next free allocation block; if there isn't enough space on the volume, no change is made, and SetEOF returns dskFulErr as its function result.

If you set the logEOF parameter to 0, all space occupied by the file on the volume is released. The file still exists, but it contains 0 bytes. Setting a file fork's end-of-file to 0 is therefore not the same as deleting the file (which removes both file forks at once).

noErr0No error
dskFulErr-34Disk full
ioErr-36I/O error
fnOpnErr-38File not open
wPrErr-44Hardware volume lock
fLckdErr-45File is locked
vLckdErr-46Software volume lock
rfNumErr-51Bad reference number
wrPermErr-61Read/write permission doesn't allow writing
For a description of the logical and physical end-of-file, see the section "File Access Characteristics" on page 1-8.

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© Apple Computer, Inc.
2 JUL 1996