1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
overflow:
This function is called on output, when there is no buffer, or no
space in the existing buffer. If you want buffering, the buffer
should be set up in the first call to overflow. The argument is the
character to be output, or EOF. For historical reasons, it is
probably advisable to call sync on EOF.
The exact functionality of this function will depend on the
buffering strategy used. Without buffering, just output the
argument, returning the character output, or EOF on error. With
buffering: if there is no buffer, create one, otherwise flush it,
and insert the character into the buffer. (Use the function setp to
initialize the buffer, or to reset it to empty once you've flushed
it, and the functions gptr and egptr to get the current values.)
underflow:
This function is called on input, which is a little more
complicated. In particular, although the function returns the next
character in the stream, it does *not* extract it from the stream.
Input *must* be buffered, although a one character buffer is
sufficient. Also, there is no guarantee that the get buffer will be
empty when this function is called, so you have to check that. In
all cases, when you return, 1) the next character must be present in
the buffer -- if there wasn't a buffer before, you have to create
one, and 2) that character must be returned.
|
