Arguments and Values
read-char-no-hang returns a character from input-stream if such a character is available. If no character is available, read-char-no-hang returns nil.
If recursive-p is true, this call is expected to be embedded in a higher-level call to read or a similar function used by the Lisp reader.
If an end of file occurs and eof-error-p is false, eof-value is returned.
read-char-no-hang is exactly like read-char, except that if it would be necessary to wait in order to get a character (as from a keyboard), nil is immediately returned without waiting.