What is the meaing of real friend ?

One of my friends called me and said one of her friends was not even happy to find out she finally learn how to blog and make money out of blogging.
I came across friends who act like her friend she just mentioned.
I find it rare to find friends who are happy with my success and who would actually celebrate my success. Incidentally , I found there are more friends who feel sad for me if I failed, they would lend me a shoulder to cry.
What about you ? What is your definition of friend ?