1 online and 3 in person technical questions, 3 of which I had to answer in C (using a compiler so old that it wouldn't allow for variable initialization inside control statements); they did, however, have automated tests to check for the validity of the solutions.

I solved all problems within what I'd call quite a reasonable time and was then asked by the "engineer" that interviewed me what he thought and why the interview process was so easy. He shrugged at the second question and informed me that despite my answers, I likely couldn't be hired because age and experience didn't match with the profile they needed (I had both the age and experience on my CV and LinkedIn profile).

I must admit, I'm quite annoyed by the fact that they wasted my time with interviews only to inform me my profile didn't fit the job, despite having handed them all the information to decide that beforehand.

The other weird thing is that the position called for someone with good mastery of C++11&14, and all the questions were to be answered in very archaic C, using no external libraries. Though I'd say the difficulty of them was reasonably small in order for them not to pose a challenge if you read 1/3 of K&R.

Remove certain characters from a string and split it in a defined pattern.