What is the difference between using を and と with the verb 言う?

Question

I apologize if this is a basic question, but it's something I've never been entirely clear on. When using the verb 言う (to say), I can never figure out whether to use the particle -と or the particle -を for the thing being said. I know that -と　is used for quotations, but what about when the thing being said is not a direct quotation? For example, is it acceptable to say:

彼女は何と言いましたか。
What did she say?

or

先生が宿題の締切りと言いましたか。
Did the teacher say what the deadline on the homework is?

In these two situations, I'm not sure whether to use を or と. Can anyone tell me what the difference between is?

Answer 1

I feel like this has been asked before, but I can't find it if it has. You've got it spot on with と being the quotation marker; that is Xと言う means that X was literally (more or less) what was said. Using を is more about the meaning/gist/essence of what is said. Here's a pair that I always remember to help distinguish them.

• なにを言ってるのか？　→　"What are you saying?" meaning "I don't understand what you're talking about"
• なんと言ってるのか？　→　"What are you saying?" meaning "I don't/can't understand the words you're speaking" (maybe they are mumbling; phone conversation static-y and breaking up; etc.)

Or this set

• なにを言ったらいいか？　→　"What/How should I say (this)?" meaning "What's the best way for me to explain this?"
• なんと言ったらいいか？　→　"What should I say?" meaning "What's the best wording for what I want to say?"

With your examples, the first one could be either - 彼女は何を／と言いました？ - but again, the meaning would change slightly (the meaning or exact wording of what she said) as I mentioned above. With the second one, を is more correct for the context.

• 先生が宿題の締切を言いましたか。　→　Did the teacher tell us the deadline for the homework?　→　The meaning of "the homework's deadline" would be an exact date/time.
• 先生が宿題の締切といいましたか。　→　Did the teacher say "the homework's deadline"?　→　Not likely that the teacher would have said that exact phrase.