Palindrome Checker

In short A palindrome reads the same backwards as forwards, and checking one means deciding what to ignore. "A man, a plan, a canal: Panama" is a palindrome by the usual convention, which ignores case, spaces and punctuation; by a strict character-for-character comparison it is not. This tool applies the conventional reading, which is what almost everyone means. Numbers work the same way — 12321 is a palindrome and 12345 is not — and the same test is used in programming exercises constantly, which is why it is one of the most common interview questions there is. The technical detail worth knowing is the same one that affects reversing text: comparing by code unit breaks on emoji and accented characters, so a correct check compares graphemes. That is done here. Words that are palindromes are short and few — level, radar, rotor, kayak — while the interesting ones are phrases, and the longest well-known English example is usually given as "A man, a plan, a canal: Panama" itself.