Regexp to accept ONLY Yes or No and should not be case sensitive

Question

Here is my regexp to accept only Yes or No (not case sensitive). Is there a better way to do it? Thanks

preg_match('/^(?:Yes\b|YES\b|yes\b|No\b|NO\b|no\b)/',$input)

Answer 1

You may use i modifier.

preg_match('~^(?:Yes|no)\b~i', $input);

Add end of the line anchor $ if necessary.

preg_match('~^(?:Yes|no)$~i', $input);