Newb Question gets() vrs cin.geline()

I was wondering what the diffrence between the two as far as reading info.

cout << "Enter a string: ";
gets(var);

or
cout << "Enter a string: ";
cin.getsline(var, 40);

gets seems shorter, but is there a reason to use one over the other?
Thanks

I can think of 2 quick reasons

1. gets does not protect against buffer overflow, getline does

2. you shouldn't mix and match i/o streams, they may not be synchronised. For instance, gets() followed by getline might read the same information.

Thanks a lot, good to know, I am working my way through two diffrent books and one of them used gets() exclusivly, and the other doesnt even mention it!
thanks again