User Tools


Function LISTEN

Syntax

  • listen &optional input-streamgeneralized-boolean

Arguments and Values

Description

Returns true if there is a character immediately available from input-stream; otherwise, returns false. On a non-interactive input-stream, listen returns true except when at end of file. If an end of file is encountered, listen returns false. listen is intended to be used when input-stream obtains characters from an interactive device such as a keyboard.

Examples

(progn (unread-char (read-char)) (list (listen) (read-char)))

1

(T #\1)

(progn (clear-input) (listen))

NIL ; Unless you're a very fast typist!

Side Effects

None.

Affected By

Exceptional Situations

None.

See Also

Notes

None.