read -d'' -n1

[Jan Schampera]

Hello,

don't ask about the detail how I originally invented this code, but I 
stepped over something I really can't explain:


1) Why doesn't this print anything

while read -d'' -n1 ch; do
  echo "$ch"
done <<< $'hello\nworld'


2) Why does this print something, but only up to the hyphen?

while read -d'' -n1 ch; do
  echo "$ch"
done <<< $'hello\nwor-ld'



Verified on 2.04, 3.2.39, 4.1, so I wonder if I have a misunderstanding 
here.

J.