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Reference for unit 'sysutils' (#rtl)

FileCreate

Create a new file and return a handle to it.

Declaration

Source position: filutilh.inc line 172

function FileCreate(

const FileName: UnicodeString

):THandle; function FileCreate(

const FileName: UnicodeString;

Rights: Integer

):THandle; function FileCreate(

const FileName: UnicodeString;

ShareMode: Integer;

Rights: Integer

):THandle; function FileCreate(

const FileName: RawByteString

):THandle; function FileCreate(

const FileName: RawByteString;

Rights: Integer

):THandle; function FileCreate(

const FileName: RawByteString;

ShareMode: Integer;

Rights: Integer

Description

FileCreate creates a new file with name FileName on the disk and returns a file handle which can be used to read or write from the file with the FileRead and FileWrite functions.

If a file with name FileName already existed on the disk, it is overwritten.

The ShareMode parameter determines how file sharing is handled for the new file. It can have one or more of the following values, OR-ed together:

Name	Description
fmShareCompat	Open file in DOS share-compatibility mode
fmShareDenyNone	Do not lock file.
fmShareDenyRead	Lock file so other processes cannot read.
fmShareDenyWrite	Lock file so other processes can only read.
fmShareExclusive	Lock file for exclusive use

The optional Rights parameter only has an effect under UNIX, where it can be used to set the mode (read, write, execute, sticky bit, setgid and setuid flags) of the created file to the specified custom value. On other platforms, the Rights parameter is ignored.

Errors

If an error occurs (e.g. disk full or non-existent path), the function returns THandle(-1).

See also

FileClose		Close a file handle.
FileWrite		Write data from a buffer to a given file handle.
FileOpen		Open an existing file and return a file handle
FileRead		Read data from a file handle in a buffer.
FileTruncate		Truncate an open file to a given size.
FileSeek		Set the current file position on a file handle.

Example

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.