flush_input/1

Module: sio

flush_input/1 — discard buffer contents of stream

FORMS

flush_input(Stream_or_Alias)

DESCRIPTION

flush_input/1 will cause the buffer contents associated with the input stream Stream_or_Alias to be discarded. This will cause the next input operation to read in a new buffer from the source attached to Stream_or_Alias.

ERRORS

Stream_or_Alias is a variable

– – – – > instantiation_error.

Stream_or_Alias is neither a variable nor a stream descriptor nor an alias

– – – – > domain_error(stream_or_alias, Stream_or_Alias)

Stream_or_Alias is not an input stream

– – – – > permission_error(input, stream, Stream_or_Alias)

NOTES

This operation is useful on streams which have an associated output stream on which prompts are being written to. Flushing the input and then performing the requisite input operation will cause a prompt to be written out prior to reading input.

This operation is also useful for use with datagram sockets. The buffer contents associated with a datagram socket represent the entire datagram. When the end of the datagram is reached, an end-of-file condition will be triggered so that the program reading the datagram will not inadvertently read beyond the datagram into the next datagram (if any). flush_input/1 should be used to reset the end-of-file indication after the datagram has been processed.

SEE ALSO

• open/4

• flush_output/[0,1]

• User Guide (Prolog I/O)