This built-in clause writes a character to the stream, the stream is altered. The output stream must be a text stream that was opened for writing.
This predicate is not part of the ISO Prolog standard, put_char/2 is equivalent to this predicate and defined by the ISO Prolog standard. If the parameter @stream_or_alias is 'user' then the character is written to the current output stream.
see also: get_char/1 get_char/2 get_code/1 get_code/2 peek_char/1 peek_char/2 peek_code/1 peek_code/2 prolog I/O put_char/1 put_code/1 put_code/2 nl/0 nl/1
| Example | |
| put(user, t). | Assume there is an output stream called user_out and it has contents: q, w, e, the stream is left as: q, w, e, t |
| Exceptions | |
| Char is a variable | an instantiation_error exception is thrown. |
| Char is neither a variable nor a character | a type_error(character, Char) is thrown |
| stream_or_alias is a variable | an instantiation_error exception is thrown |
| stream_or_alias is neither a variable nor a stream term nor an alias | a domain_error(stream_or_alias, Stream) exception is thrown, the variable Stream is assigned the incorrect stream_or_alias term |
| stream_or_alias is not associated with an open stream | an existence_error(stream, Stream) exception is thrown |
| stream_or_alias is an input stream | a permission_error(output, stream, Stream) exception is thrown |
| stream_or_alias is a binary stream | a permission_error(output, binary_stream, OutputStream) is thrown, the variable OutputStream is assigned the stream which was used as the output stream |