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copied!<p>You can use <a href="http://www.swi-prolog.org/pldoc/man?predicate=read_line_to_codes%2F2" rel="noreferrer"><code>read_line_to_codes/2</code></a> or <a href="http://www.swi-prolog.org/pldoc/man?predicate=read_line_to_codes%2F3" rel="noreferrer"><code>read_line_to_codes/3</code></a>. An example program which reads individual lines from <a href="http://en.wikipedia.org/wiki/Standard_streams#Standard_input_.28stdin.29" rel="noreferrer">stdin</a> and prints them to <a href="http://en.wikipedia.org/wiki/Standard_streams#Standard_output_.28stdout.29" rel="noreferrer">stdout</a> is the following:</p> <pre><code>read_lines([H|T]) :- read_line_to_codes(user_input, H), H \= end_of_file, read_lines(T). read_lines([]). write_lines([]). write_lines([H|T]) :- writef("%s\n", [H]), write_lines(T). main :- read_lines(X), write_lines(X). </code></pre> <p>(This uses <a href="http://www.swi-prolog.org/pldoc/man?predicate=writef%2F2" rel="noreferrer"><code>writef/2</code></a> for printing.) There are also <a href="http://www.swi-prolog.org/pldoc/doc_for?object=read_stream_to_codes%2f2" rel="noreferrer"><code>read_stream_to_codes/2</code></a> and <a href="http://www.swi-prolog.org/pldoc/doc_for?object=read_stream_to_codes%2f3" rel="noreferrer"><code>read_stream_to_codes/3</code></a>, which are not concerned with lines. The following code prints all input from stdin in one go to stdout:</p> <pre><code>main :- read_stream_to_codes(user_input, X), writef("%s", [X]). </code></pre> <p>Of course it's also possible to read from a file instead of stdin. For more, see the <a href="http://www.swi-prolog.org/pldoc/doc_for?object=section%282%2c%20%27A.20%27%2c%20swi%28%27%2fdoc%2fManual%2freadutil.html%27%29%29" rel="noreferrer"><code>readutil</code></a> library.</p>

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