Commenting just to go against the other two answers. I think it's fine to not remember things, no matter the apparent simplicity.

Quite surprised by others finding this as a... Surprise? I get there is people who never experience this, but they also not know anyone personally to whom this would happen?

I probably would've done the same. "I don't remember what the function is called" would've been fine-ish, but reaching for a regex is just insane.

I’d call this an understandable mistake on the part of the interviewer. “in” is a pretty commonly used operator. But it is also a bit unusual/trivial, in the sense that most languages would have a method or a function instead.

It’s the sort of thing where if you’ve written, like, any Python at all, it’ll be somewhere in the back of your head. It’d surface immediately on the job. But if you’d been using any other language earlier that day, it might not pop up reflexively, or in interview-stress mode.

It’s essentially trivia, and over-indexing on trivia is a mistake. But if they were a Python writer every day, I could see why they’d incorrectly expect everybody to have “in” in their l1 cache.

   if "needle" in haystack:
      print ('haystack.__contains__("needle")')

Is probably the obvious/canonical answer to the question of trying to find a substring.

So obvious that -to be fair- I blanked for a moment too. But 'in' is an operator, not a method (even though it calls __contains__ under the hood) . The question might have been slightly malformed?

Step 1: https://www.google.com/search?q=list+python+string+methods

Step 2: Parse the output with your eyes. The method is literally called "find".

This one-trick pony failure mode could perhaps have been fine for a guy who did Java and nothing but Java for 10 years, but you are supposedly the person who runs "pythonforengineers" website...

100% correct call by the interviewer.

I like such interviews. They tell me it's not a place I want to work at without wasting much time finding out.

He was being rude, but I'm equally baffled by your description. It was very weird that you couldn't figure out which method is to search for substring when you have access to google search.

And it was triply weird that when he already said he wanted the non-regex way and you insisted on that.

I've never understood this extremely common complaint. First of all if one can't remember the substring method in the language they are interviewing for, that's a red flag; extremely common standard lib functions should not be a subject for googling. But let's account for nervousness, okay. If that same candidate can't find the method by googling, it's a no-hire from me, easily.

"python find substring" gives you a valid answer on every single result. This story, and most like it, is incompetence in the python language, in googling, or both.

The interviewer was right. If you don't know "if substring in string" by memory, your python programming is substandard. This should be automatic for anyone who works with python as a primary language. But if you can't even Google to find "if substring in string", why would anyone pay you even minimum wage to be a programmer?