It's an informal usage of a dash. We often use it to prolong our tone, and make the words we said seemed more friendly to others.

in writen chinese , it is used to replace the same letter or word that appeared before

Thanks very much, Xu. =)

1. it means "from..to...", or between.. .for example : 那有差不多5~10个学生。 2. it means something what has appeared b4,it often means this in Chinese dictionary. 3. in written Chinese (especially in the talk between good friends), it often means "friendly",or just means nothing.(If u want to make urself look more lovely,u can use this,too. :P) 5. sometimes it means“ 声音延长” (I don't know how to express it in English :P). (it always be used when the person wants to be more friendly or lovely-- just as I told u,but girls use it more often than boys do ) hope it helps :)

usually means nothing just put between messages which are not complete sentences and therefore no dot between them