title: Finding the index of occurrence before the last occurrence of a string
body: <p>For example i have a string "13 + 12 + 25 + 55 + 65"
  I want to find  the index of occurrence before the last occurrence of + sign.</p>
  
  <pre><code>subString = str.substring(beginning index,str.lastIndexOf("+") - 1 ));
  </code></pre>
  
  <p>beginning index will be the index of occurrence index before last occurrence index.</p>