Problem 44397. Determine whether the input is odd, even, or neither.

Why does this not work (while Solution 1328031 does work)?

Because a comma separated list cannot be assigned to a single variable, this is how your previous solution catched the assignment error and triggered the catch statement (as desired). However, what you did here is only to generate a comma separated list without any assignment, and thus, no assignment error occurs which cannot trigger the catch statement.

Thanks, Peng Liu, for your concise explanation! It greatly helps in improving my understanding of cell variables/comma-separated lists as well as the try-catch function and error handling, which are topics that I still find quite complicated; but your comment explains it very clearly and easily! :-)

However, on closer inspection, I feel there's still something missing in the explanation. If it's merely a matter of failed/absent variable assignment to a comma-separated list, then why does this code still successfully enter into the catch statement in tests #3 and #6 (in which input x is a non-integer number)?

For the non-integer test cases #3 and #6, it is the subscript indexing error that was catched in your ans{index} indexing statement (because subscript index has to be either positive integer or logical).