tyi(+Stream, -Code)

Stream

Stream handle or alias (atom)

Code

Variable or integer.

Description

Character codes for the non-printable characters (i.e. control characters) are also acceptable.

Note tyi/2 reads from the stream in raw mode. If it is combined with the buffered predicates, it might happen that some characters typed ahead may be lost if the input device is a terminal.

Modes and Determinism

• tyi(+, -) is det

Exceptions

(4) instantiation fault

Stream is not instantiated.

(5) type error

Stream is neither a stream handle nor an atom.

(5) type error

Code is instantiated, but not to an integer.

(190) end of file reached

End of file has been reached.

(192) illegal stream mode

Stream is not an input stream.

(193) illegal stream specification

Stream is an illegal stream specification.

(198) reading past the file end

Trying to read even after the error 190 was raised.

Examples

Success:
      ?- tyi(input,Code).
      Code = 97         % press 'a'
      yes.

      ?- tyi(input,97).
                            % press 'a'
      yes.

      ?- tyi(input,Code).
      Code = 4          % press ^D
      yes.

Fail:
      ?- tyi(input, 0'b).
                            % press 'a'
      no.

Error:
      tyi(Stream,98).             (Error 4).
      tyi(input, '98').           (Error 5).
      tyi(input, 98.0).           (Error 5).
      tyi("string", A).           (Error 5).

      ?- open(file1,update,s), write(s,p),
         seek(s,0), tyi(s,Code),
      tyi(s,Code).              (Error 190).
      tyi(9,A).                  (Error 192).
      tyi(atom,A).               (Error 193).

See Also