How to write ASCII text

Hi,
i have to write ASCII characters on my pdf file, like └ , ┴, ┼, and
so on..
how can i do it? and which font i can use?
I've just tried this code:

element = eb.CreateTextRun(ss.str().c_str());
element.SetTextMatrix(2, 0, 0, 2, 0, 600);
writer.WriteElement(element);

where ss.str() is my ASCII string, but it doesn't function correctly.
The result is:

ÄÚÄÄ¿ÄÃ
ÄÄÄÄ
´ÿ³ÿÿ³ÿ³
ÿÿÿÿ
³ÿ³ÿÿ³ÿ³

any post will be useful for me.
thank you very much.
Francesco