comma splice in dialogue: "That car's new, he's not sitting in it..."

[kcchanp]

I read Harry Potter and the Philosopher's Stone and came across this sentence.

'That car's new, he's not sitting in it alone...'

I always think that a complete sentence must be ended with a full stop (and some other possible punctuation marks but definitely not a comma) so I wonder why and when I can use a comma to link two sentences.

Thank you.

 

[perpend]

When it is dialogue, and there is an ellipsis at the end (...), it's okay the way it is.

Here's more of the dialogue:

Arthur mouthed a silent thank you to his friend.
"I suppose we could take him to the zoo," said Aunt Petunia slowly, "… and leave him in the car…"
"That car's new, he's not sitting in it alone…"

http://secretthought7.livejournal.c...ter 3 PS The Vanishing Glass Part 1&hashtags=

In normal grammar, you are right, there should be a period.

 

[owlman5]

I agree with your thoughts about full stops, kcchanp. I don't think you should use this sentence as a model for your own punctuation. If I didn't use a period (full stop), I'd use a semicolon instead of a comma.

 

[Keith Bradford]

...I don't think you should use this sentence as a model for your own punctuation...

I agree. More generally, I don't think you should take anything by J.K.Rowling as a model for good English. Her punctuation, grammar and vocabulary are often very approximate, even when they haven't been hacked about by her American publishers.