title: Calculate number of a letter in a string using Dart
body: <p>I try to calculate how many letter "a" i have in the sentence: "Hello Jordania".</p>
  
  <p>I find the function contains. I using it like this:</p>
  
  <pre><code>  var phrase = "Hello Jordania;
    var comptenbrdea = phrase.contains('a');
    print(comptenbrdea);
  </code></pre>
  
  <p>I get "True" as response. Normal you will say, I know, but I dont find the right function to calculate how many time i get an a. I can maybe do something with a loop if I can check every single character? ... I'm lost on <a href="http://www.dartlang.org/search.html?cx=011220921317074318178%3Ai4mscbaxtru&amp;ie=UTF-8&amp;hl=en&amp;q=string_scanner" rel="noreferrer">http://www.dartlang.org/search.html?cx=011220921317074318178%3Ai4mscbaxtru&amp;ie=UTF-8&amp;hl=en&amp;q=string_scanner</a> ... Can some one help me ?</p>