Article #26416: How to move a string into a TMemoryStream or TFileStream.

Question: How do I move a string into a TMemoryStream (or a TFileStream)?

Answer: Here is a code sample of how to do this with a TMemoryStream. It could easily be extended to work with a TFileStream too:

procedure TForm1.Button1Click(Sender: TObject);
var
SourceString: string;
MemoryStream: TMemoryStream;
begin
SourceString := 'Hello, how are you doing today?';
MemoryStream := TMemoryStream.Create;
try
// Write the string to the stream. We want to write from SourceString's
// data, starting at a pointer to SourceString (this returns a pointer to
// the first character), dereferenced (this gives the actual character).
MemoryStream.WriteBuffer(Pointer(SourceString)^, Length(SourceString));
// Go back to the start of the stream
MemoryStream.Position := 0;
// Read it back in to make sure it worked.
SourceString := 'I am doing just fine!';
// Set the length, so we have space to read into
SetLength(SourceString, MemoryStream.Size);
MemoryStream.ReadBuffer(Pointer(SourceString)^, MemoryStream.Size);
Caption := SourceString;
finally
MemoryStream.Free;
end;
end;