ons are supported by the device. The category tag <A HREF="../guide/traits.html#category_tags"><CODE>source_tag</CODE></A> indicates that only <A HREF="../functions/read.html"><CODE>read</CODE></A> is supported.</P>

<P>The member function <CODE>read</CODE> reads up to <CODE>n</CODE> characters into the buffer <CODE>s</CODE> and returns the number of characters read, unless that number is <CODE>0</CODE> and end-of-stream has been reached, in which case the special value <CODE>-1</CODE> is returned. In gener