title: find last location in a string
body: <p>i have a string </p>
  
  <p>a = "hai my name is prasanth Madhavan"</p>
  
  <p>and i would like to replace the space btw prasanth and Madhavan with a period.</p>
  
  <p>when i use a.find("prasanth") it gives the location of p i.e the begining of the search string. is ther a way to get the location of the ending of the string using find??</p>