C : strrchr() analyze and example get self executable directory function.

strrchr() function will return a pointer to the last occurrence.
Another example is modify from Advanced Linux Programming chapter 11.We can get a sub-sting without the occurrence with sub two pointer.





Ref:
   1. http://www.cplusplus.com/reference/cstring/strrchr/
   2. Advanced Linux Programming by Mark Mitchell, Jeffrey Oldham, and Alex Samuel www.newriders.com