[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] |
Set the current file position on a file handle.
Source position: filutilh.inc line 221
function FileSeek( |
Handle: THandle; |
FOffset: LongInt; |
Origin: LongInt |
):LongInt; |
Handle: THandle; |
FOffset: Int64; |
Origin: LongInt |
):Int64; |
FileSeek sets the file pointer on position Offset, starting from Origin. Origin can be one of the following values:
If successful, the function returns the new file position, relative to the beginning of the file.
Remark: | The above mentioned constants do not exist in Delphi. |
On error, -1 is returned.
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Close a file handle. |
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Write data from a buffer to a given file handle. |
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Create a new file and return a handle to it. |
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Open an existing file and return a file handle |
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Read data from a file handle in a buffer. |
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Truncate an open file to a given size. |
Program Example37; { This program demonstrates the FileCreate/FileSeek/FileReed/FileTruncate functions } Uses sysutils; Var I,J,F : Longint; Begin F:=FileCreate ('test.dat'); If F=-1 then Halt(1); For I:=0 to 100 do FileWrite(F,I,SizeOf(i)); FileClose(f); F:=FileOpen ('test.dat',fmOpenRead); For I:=0 to 100 do begin FileRead (F,J,SizeOF(J)); If J<>I then Writeln ('Mismatch at file position ',I) end; FileSeek(F,0,fsFromBeginning); Randomize; Repeat FileSeek(F,Random(100)*4,fsFromBeginning); FileRead (F,J,SizeOf(J)); Writeln ('Random read : ',j); Until J>80; FileClose(F); F:=FileOpen('test.dat',fmOpenWrite); I:=50*SizeOf(Longint); If FileTruncate(F,I) then Writeln('SuccessFully truncated file to ',I,' bytes.'); FileClose(F); End.