Based on this question from Code Review
Given a non-empty string of printable ASCII characters, output the second non-repeating character. For example, for input
- A single string, in any suitable format.
- The second character that doesn't repeat, when reading left-to-right, again in a suitable format.
- The output character is case-insensitive.
- If no such character exists (e.g., all characters repeat), output an empty string.
- The algorithm should ignore case. That is,
dcount as the same character.
- Either a full program or a function are acceptable.
- The input string will be guaranteed non-empty (i.e., at least one character in length).
- The input string is ASCII. Any valid character could repeat, not just alphanumeric (this includes spaces).
- Standard loopholes are forbidden.
- This is code-golf so all usual golfing rules apply, and the shortest code (in bytes) wins.
Input is on first line, output is on second line.
DEFD F FEED D This is an example input sentence. x ...,,,..,,!@ @ ABCDefgHijklMNOPqrsTuVWxyz B AAAAAABBBBB Thisxthis This this. .