It’s common for companies to have a set of technical questions to perform at programming interviews. We may have a set of generic questions, and also questions specific to the language and technologies we use. Having this script of questions is great for having a common ground between different interviews. If we always ask the same questions, it’s easier to compare candidate performances.
With time I’ve came up with my own set of questions. I have a different style. I favour open questions that let the candidates talk freely about their past experiences.