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| ANSI Common Lisp 21 Streams 21.2 Dictionary of Streams
21.2.17 read-char | Function
  Syntax: read-char `&optional` input-stream eof-error-p eof-value recursive-p char Arguments and Values: 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. Description: 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 file2 occurs and eof-error-p is false, eof-value is returned. Examples:
       (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
Affected By: *standard-input*, *terminal-io*. Exceptional Situations: If an end of file2 occurs before a character can be read, and eof-error-p is true, an error of type end-of-file is signaled. See Also: read-byte, read-sequence, write-char, read Notes: The corresponding output function is write-char. Allegro CL Implementation Details: None.

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