default-parameter-values/assignment.html.template

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>PVM Assignment</title>
    <%= stylesheets('pvm') %>
    <%= scripts('jquery', 'jquery-ui', 'underscore', 'ace/ace', 'source-editor', 'revealer', 'quiz', 'html') %>
  </head>

  <body>
    <header>
      <div class="center-vertically">Default Parameter Values</div>
    </header>
    <div id="contents">
      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x = 5)
             {
               return x;
             }

             int main()
             {
               std::cout << foo(1) << foo(2) << foo();
             }
           END

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
           END
         end
      %>

      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x = 5, bool y = true)
             {
               return y ? x * 10 : x;
             }

             int main()
             {
               std::cout << foo(false);
             }
           END

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
             <div data-revealer="Show explanation" class="explanation">
               <p>
                 C++ will not try to match types, so <code>false</code> will assigned to <code>x</code>, not to <code>y</code>.
                 During this process, <code>false</code> must be converted to an <code>int</code>, which is possible: <code>false</code> gets turned into <code>0</code>.
               </p>
             </div>
           END
         end
      %>

      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x = 5, int y)
             {
               return x * y;
             }

             int main()
             {
               std::cout << foo(1, 2);
             }
           END

           self.output = 'DNC'

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
             <div data-revealer="Show explanation" class="explanation">
               <p>
                 In <code>foo</code>'s definition, <code>x</code> has a default argument value, meaning
                 that all subsequent parameters must also get one.
               </p>
             </div>
           END
         end
      %>

      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x = 5);

             int main()
             {
               std::cout << foo();
             }

             int foo(int x)
             {
               return x;
             }
           END

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
           END
         end
      %>

      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x = 5);

             int main()
             {
               std::cout << foo();
             }

             int foo(int x = 5)
             {
               return x;
             }
           END

           self.output = 'DNC'

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
             <div data-revealer="Show explanation" class="explanation">
               <p>
                 This code won't compile as the compiler encounters default values for <code>x</code> twice.
                 Even if these values agree, this is forbidden.
               </p>
             </div>
           END
         end
      %>

      <%=
         exercise(Lib::Interpretation) do
           self.source = <<-END
             #include <iostream>

             int foo(int x);

             int main()
             {
               std::cout << foo();
             }

             int foo(int x = 5)
             {
               return x;
             }
           END

           self.output = 'DNC'

           <<-END
             <p>What is the output of the following code? Enter <code>DNC</code> if the code does not compile. Enter <code>???</code> if its behaviour is undefined.</p>
             #{show_source_editor}
             #{if input then show_input else '' end}
             #{show_output_field}
             <div data-revealer="Show explanation" class="explanation">
               <p>
                 At the time <code>foo</code> is called, the compiler hasn't encountered a default value for <code>x</code> yet.
               </p>
             </div>
           END
         end
      %>

      <%=
        exercise do
          extend SourceCodeMixin

          <<-END
            <p>
              Rewrite the class <code>Counter</code> so that it makes use of default parameter values where possible.
            </p>
          END
        end
      %>
    </div>
  </body>

  <script>
    Quiz.formatQuizzes();
    SourceEditor.initialize();
    Revealer.initialize();
  </script>
</html>