Writing a string to a TFileStream in Delphi 2010 - delphi

Question

I have Delphi 2007 code that looks like this:
procedure WriteString(Stream: TFileStream; var SourceBuffer: PChar; s: string);
begin
StrPCopy(SourceBuffer,s);
Stream.Write(SourceBuffer[0], StrLen(SourceBuffer));
end;
I call it like this:
var
SourceBuffer : PChar;
MyFile: TFileStream;
....
SourceBuffer := StrAlloc(1024);
MyFile := TFileStream.Create('MyFile.txt',fmCreate);
WriteString(MyFile,SourceBuffer,'Some Text');
....
This worked in Delphi 2007, but it gives me a lot of junk characters in Delphi 2010. I know this is due to unicode compliance issues, but I am not sure how to address the issue.
Here is what I've tried so far:
Change the data type of
SourceBuffer(and also the parameter
expected by WideString) to PWideChar
Every one of the suggestions listed
here
What am I doing wrong?

Answer 1

You don't need a separate buffer to write a string to a stream. Probably the simplest way to do it is to encode the string to UTF8, like so:
procedure TStreamEx.writeString(const data: string);
var
len: cardinal;
oString: UTF8String;
begin
oString := UTF8String(data);
len := length(oString);
self.WriteBuffer(len, 4);
if len > 0 then
self.WriteBuffer(oString[1], len);
end;
function TStreamEx.readString: string;
var
len: integer;
iString: UTF8String;
begin
self.readBuffer(len, 4);
if len > 0 then
begin
setLength(iString, len);
self.ReadBuffer(iString[1], len);
result := string(iString);
end;
end;
I've declared TStreamEx as a class helper for TStream, but it shouldn't be too difficult to rewrite these as a solo procedure and function like your example.

Answer 2

Delphi 2010 has a nice solution for this, documented here:
http://docwiki.embarcadero.com/CodeExamples/en/StreamStrRdWr_%28Delphi%29
var
Writer: TStreamWriter;
...
{ Create a new stream writer directly. }
Writer := TStreamWriter.Create('MyFile.txt', false, TEncoding.UTF8);
Writer.Write('Some Text');
{ Close and free the writer. }
Writer.Free();