I'm pretty new to the Stack Exchange network. I'm currently teaching myself programming and have been getting help with code issues on Stack Overflow. I've used Code Review a couple times and found it helpful, but users want working code to review. So my question is (if one wanted to stick to just one website), which site it better for help with code?
Stack Overflow is there to help with specific coding issues.
Code Review is there for making working code even better.
There is no Stack Exchange site for debugging code for you.
Adding on to Oded's answer, the purpose of the Stack Exchange sites is to create a repository of knowledge for future visitors. Asking a specific question, like "Why does calling foo from bar when baz is set to qux result in error xyz?" may be useful to other visitors with the same specific issue.
But debugging questions, like "This code doesn't work. Can you spot the problem?" really is not useful to others. It's useful only to you and only for today. Even if you learn something, it's unlikely that that information will be discoverable by others. That's why we don't allow general "I don't know where the problem is" debugging questions.
Neither site will work for you unless you learn to use the tools and focus the problem.
Code review is to ask people, 'is there a better way to do this?' People there are not going to be great enthusiasts for 'this has a bug it it, can you please locate Waldo for me?'
And stackoverflow is legendarily unsympathetic.
If you need help learning to use a debugging tool, stackoverflow is there for you. You'll need to phrase questions that focus on the tool, not your buggy code.
If you need help coming up with a debugging approach to some complex misbehavior, you'll again need to phrase a question in terms of your need for help with an approach or technique for isolating the problem, rather than for someone to do your work for you and find the bug.
Don't stick to just one site: use each for what it's intended. Asking for a code review of working code on SO will fail, just as asking a "Why doesn't my
fobricate() call work?" will fail on CodeReview.
Learn to use the right tool for the job.