get-char, read-char - read a character from a textual input port

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LIBRARY

(import (rnrs))                     ;R6RS
(import (rnrs io ports))            ;R6RS
(import (rnrs io simple))           ;R6RS, read-char
(import (scheme r5rs))              ;R7RS
(import (scheme base))              ;R7RS

SYNOPSIS

(get-char textual-input-port)       ;R6RS only
(read-char)
(read-char textual-input-port)

DESCRIPTION

If a complete character is available before the next end of file, that character is returned, and the input port is updated to point past that character. If an end of file is reached before any data are read, the end-of-file object is returned.

If textual-input-port is omitted, it defaults to the value returned by current-input-port(3scm)

RETURN VALUES

R6RS

There is a single, unique end-of-file object.

EXAMPLES

(let lp ()
  (let ((c (read-char)))
    (unless (eof-object? c)
      (write-char (char-upcase c))
      (lp))))

COMPATIBILITY

ERRORS

&assertion (R6RS)

The wrong number of arguments was passed or an argument was outside its domain.

&i/o-decoding (R6RS)

The port's transcoder is in raise mode and it encountered an invalid byte sequence.

&i/o-read (R6RS)

There was an I/O error during the read operation.

&i/o-port (R6RS)

This condition specifies the port object related to an &i/o-read condition.

R7RS

The assertions described above are errors. Implementations may signal an error, extend the procedure's domain of definition to include such arguments, or fail catastrophically.

SEE ALSO

STANDARDS

HISTORY

AUTHORS