Node:Unreading Idea, Next:How Unread, Up:Unreading
Here is a pictorial explanation of unreading. Suppose you have a
stream reading a file that contains just six characters, the letters
foobar
. Suppose you have read three characters so far. The
situation looks like this:
f o o b a r ^
so the next input character will be b
.
If instead of reading b
you unread the letter o
, you get a
situation like this:
f o o b a r | o-- ^
so that the next input characters will be o
and b
.
If you unread 9
instead of o
, you get this situation:
f o o b a r | 9-- ^
so that the next input characters will be 9
and b
.