read-char {&optional input-stream eof-error-p eof-value recursive-p} => char
input-stream---an input stream designator. The default is standard input.
eof-error-p---a generalized boolean. The default is true.
eof-value---an object. The default is nil.
recursive-p---a generalized boolean. The default is false.
char---a character or the eof-value.
read-char returns the next character from input-stream.
When input-stream is an echo stream, the character is echoed on input-stream the first time the character is seen. Characters that are not echoed by read-char are those that were put there by unread-char and hence are assumed to have been echoed already by a previous call to read-char.
{ }{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_2 occurs and eof-error-p is false, eof-value is returned.
(with-input-from-string (is "0123")
(do ((c (read-char is) (read-char is nil 'the-end)))
((not (characterp c)))
(format t "~S " c)))
|> #\0 #\1 #\2 #\3
=> NIL
*standard-input*, *terminal-io*.
If an end of file_2 occurs before a character can be read, and eof-error-p is true, an error of type end-of-file is signaled.
section read-byte [Function] ,
section read-sequence [Function] ,
section write-char [Function] , @xref{read; read-preserving-whitespace}
The corresponding output function is write-char.
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