While sorting the strings, we need to swap only pointers instead of swapping the whole string which helps in efficient use of memory and time.When we have lot of data,this method should be preferred. Follow this link for an example and more explanation- http://ee.hawaii.edu/~tep/EE160/Book/chap9/section2.1.4.html
Say you are given an array which has all duplicate members except one, which out this non-duplicate member.