Difference : "I have few friends" and "I have a few friends"

Both ‘few’ and ‘a few’ indicate a small quantity or number.

While ‘a few’ refers to a small quantity or number in a positive way, ‘few’ has a negative connotation.

“I have got a few friends” means I have a small but enough number of friends.
On the other hand, “I have got few friends” means I have almost no friends.

 But the phrase ‘quite a few’ indicates a fairly large number. Example: Quite a few people have cars.

The above mentioned rule is applicable for ‘a little’ and ‘little’. The only difference is that while ‘a little’ or ‘little’ is used with uncountable nouns, ‘a few’ or ‘few’ is used with countable nouns.