Try this:
str = "http://farm6.static.flickr.com/5149/5684108566_aed8b9b52d_s.jpg"str = str.replace("_s","_m")If you want to be sure that only the las part is changed and you know all are
.jpgfiles you can use:
str = "http://farm6.static.flickr.com/5149/5684108566_aed8b9b52d_s.jpg"str = str.replace("_s.jpg","_m.jpg")To give some more context and avoid changes on the middle of the url.
