The index one greater than the last valid character in the input
stream buffer.
This value should always be nonnegative
and not larger than the length of <code>buf</code>.
It is one greater than the position of
the last byte within <code>buf</code> that
can ever be read from the input stream buffer.
The index one greater than the last valid character in the input stream buffer. This value should always be nonnegative and not larger than the length of <code>buf</code>. It is one greater than the position of the last byte within <code>buf</code> that can ever be read from the input stream buffer.