get_char(+Stream, -Char)

Stream

Stream handle or alias (atom)

Char

Single character string or variable.

Description

Note that this predicate returns a string, while the corresponding predicate iso:get_char/2 returns an atom!

Modes and Determinism

• get_char(+, -) 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

Char is instantiated, but not to a single character string.

(190) end of file reached

End of file has been reached.

(192) illegal stream mode

Stream is not open for reading.

(193) illegal stream specification

Stream is not a valid stream number.

Examples

   Success:
      ?- get_char(input,Char).
       a
      Char = "a"
      yes.

      ?- get_char(input, "b").
       b
      yes.

      ?- sh('cat file1').
      p
      yes.
      ?- open(file1, update,s),
         get_char(s,X).
      X = "p"
      yes.
Fail:
      ?- get_char(input, "b").
       a
      no.

Error:
      get_char(Stream, "b").             (Error 4).
      get_char(input, 'b').              (Error 5).
      get_char(input, 98.0).             (Error 5).
      get_char("string", Char).          (Error 5).
      get_char(null,Char).              (Error 190).
      get_char(9,Char).                 (Error 192).
      get_char(atom,Char).              (Error 193).

See Also