TFileStream

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A TFileStream is a descendant of TStream that gets/stores its data from/to a file on disk.

Constant	Decimal	Description
fmCreate	65280	Creates a new file
fmOpenRead	0	opens a file for reading
fmOpenWrite	1	opens a file for writing
fmOpenReadWrite	2	opens a file for reading and writing
fmShareDenyWrite	32	prohibit writing if file is already opened

• read entire file fnam into a string.

function readstream(fnam: string): string;
var
  strm: TFileStream;
  n: longint;
  txt: string;
begin
  txt := '';
  strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite);
  try
    n := strm.Size;
    SetLength(txt, n);
    strm.Read(txt[1], n);
  finally
    strm.Free;
  end;
  result := txt;
end;

• read 8 bytes of fnam into a byte array:

..
type
    TByte8Array = array [0..7] of byte;
..
function readstream(fnam: string; position= integer): TByte8Array;
var
  strm : TFileStream;
begin
  strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite);
  try
    strm.Position:=position;
    strm.Read (Result[0],8);
  finally
    strm.Free;
  end;
end;

• Write a string txt to the file fnam.

procedure writestream(fnam: string; txt: string);
var
  strm: TFileStream;
  n: longint;
begin
  strm := TFileStream.Create(fnam, fmCreate);
  n := Length(txt);
  try
    strm.Position := 0;
    strm.Write(txt[1], n);
  finally
    strm.Free;
  end;
end;

See also

• File types
• TFileStream doc
• TStream doc