title: Trying to place objects into unordered_map
body: <p>I'm trying to create a unordered_map that has an integer as a key and a Transition object as the value.... Here's what I have:</p>
  
  <p>Instantiation</p>
  
  <pre><code>unordered_map&lt;int, Transition&gt; transitions;
  </code></pre>
  
  <p>Transition Class Declaration:</p>
  
  <pre><code>class Transition{
  
      public:
              Transition(int n, char r, char m);
              ~Transition();
              int getNextState();
              char getReplacement();
              char getMovement();
  
      private:
              int nextState;
              char replacement;
              char movement;
  };
  </code></pre>
  
  <p>Adding a transition to the map</p>
  
  <pre><code>// Create transition object
  Transition t(r,b,x);
  transitions[keyForMap] = t;
  </code></pre>
  
  <p>I'm getting this error:</p>
  
  <pre><code>/usr/include/c++/4.7/bits/hashtable_policy.h:445:24: error: no matching function for call to ‘Transition::Transition()’
  /usr/include/c++/4.7/bits/hashtable_policy.h:445:24: note: candidates are:
  In file included from ball_p1.cpp:6:0:
  Transition.h:4:3: note: Transition::Transition(int, char, char)
  Transition.h:4:3: note:   candidate expects 3 arguments, 0 provided
  Transition.h:1:7: note: constexpr Transition::Transition(const Transition&amp;)
  Transition.h:1:7: note:   candidate expects 1 argument, 0 provided
  </code></pre>
  
  <p>Do I need to somehow specify the parameters that the constructor takes somewhere in the instantiation? What am I doing wrong? Thanks for any help ahead of time.</p>