PhD in industry here, I interview a candidate a week.
I'll keep it simple. Every time that you didn't feel like you did well in an interview question, go home and study to get better at those questions.
Unless you're applying to a research lab, realize that you're applying to jobs that you're probably underqualified for. Your PhD says that you haven't been making production quality code for a few years.
E.g. Learn the damn stl containers. It takes a fucking weekend. They have very similar APIs and are mostly sensible. Just because you finished a PhD doesn't mean that you're done learning, much the opposite.