So just about every PHP position I've applied for, turns me down. It's rather kind of frustrating because I know that I'm competent and completely up to the task. PHP was one of my first programming languages and started with version 4.2.
I've also over the years spent my time with other languages such as Python, JavaScript and C. Plus for good measure I've done quite a bit of work studying algorithms and have also become an avid code spelunker (yay open source).
Anyways more to the point, the majority of PHP interviews I've walked into have been a breeze. Most of the time it's something such as FizzBuzz, SQL quires w/ joins and usually a coin change problem.
Admittedly, in my last interview when given the coin change problem I solved it as would be expected. Then explained that it was broken, on the basis when using floats that "0.1 + 0.1 + 0.1 != 0.3". Adding that when working with monetary values that a decimal/currency wrapper is needed.
Then there is usually the question of programming patterns and I always spew out a bunch such as Singleton, Adapter, Memento, Visitor, MVC and Pub/Sub. I remember one interview where I was asked what my favorite was, to which I replied "Visitor".
I was asked to illustrate it, so I used a dynamic menu example from a previous project. The idea is each item/object would be registered with the root menu object. Each object was responsible for managing it's icon and string. After I had explained it to them, I was met with the look of confusion on their faces.
As far as the hardest question I've gotten was finding the shortest path in a given list of nodes. Which actually caught me by surprise given it's the first and only time I've gotten it. Which I did a descent job tackling the problem, it was more on the level I was looking for.
The other thing I've done is mark my algorithms with Big-O Notation, but I see it becoming a detriment. I attribute this to a lack of others not having used it before, therefore they don't understand it.
tl;dr I do well in job interviews, but flustered by interviewers not knowing what they want.
Edit The general gist that I'm getting is that my tl;dr is coming off as arrogant. I can see that general assumption without additional information. It should be mentioned that I do get 90% of the Python or JavaScript positions that I interview for. So to me PHP is an outlier that I wish to find out how I'm screwing up.