title: String expression does not work with ng-bind directive whereas number expression does?
body: <p>See below examples of AngularJS code:</p>
  
  <p><strong>Ex. 1:</strong></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"&gt;&lt;/script&gt;
      &lt;body&gt;
          &lt;div ng-app="" ng-init="quantity=1;cost=5"&gt;
              &lt;p&gt;Total in dollar: &lt;span ng-bind="{{quantity * cost}}"&gt;&lt;/span&gt;&lt;/p&gt;
          &lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Output of above program is: <strong>Total in dollar: 5</strong></p>
  
  <p><strong>Ex. 2:</strong></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"&gt;&lt;/script&gt;
      &lt;body&gt;
          &lt;div ng-app="" ng-init="firstName='John';lastName='Doe'"&gt;
              &lt;p&gt;The full name is: &lt;span ng-bind="{{firstName + ' ' + lastName}}"&gt;&lt;/span&gt;&lt;/p&gt;
          &lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Output of above program is: <strong>The full name is:</strong></p>
  
  <p>Why the full name is not appearing in output of second program?</p>