Either is fine, but:
Posting too many unrelated functions in the same question may become a mess and hurt the quality of your question. Make sure you note which function is for which problem.
Posting too many questions in a short period of time will make sure the questions are less-well received. For one, it makes for poorer questions. Why bother reviewing someone's code if they've made the same mistake in the next 3 questions which are already posted as well?
A third approach you haven't mentioned yet, would be an option if you're not in a hurry. Post the first piece of code and use the feedback to improve the second before posting the second. Use the feedback of both to improve the third before posting the third. At that rate, your fourth or so question should contain some pretty decent code even if you start out with crap on the first (in theory).