title: modifying a private int in a const function issue
body: <p>My code is below and i am having an error with  numberCollisions += collisionNum;
  The error states, 'numberCollisions' cannot be modified because it is being used through a  const object. Is this error just popping up because it is a const function? Thanks for the help.</p>
  
  <pre><code>int HashTable_qp::findPos( const string &amp; x ) const
  {
      /* 1*/      int collisionNum = 0;
      /* 2*/      int currentPos = myhash( x, array.size( ) );
  
      /* 3*/      while( array[ currentPos ].info != EMPTY &amp;&amp;
          array[ currentPos ].element != x )
      {
          /* 4*/          currentPos += 2 * ++collisionNum - 1;  // Compute ith probe
          /* 5*/          if( currentPos &gt;= array.size( ) )
              /* 6*/              currentPos -= array.size( );
      }
      numberCollisions += collisionNum;
      /* 7*/      return currentPos;
  }
  </code></pre>