Need help with $ in paterm

Question

why only pattern 3 and 4 matches
https://code.sololearn.com/ckOirMHWK8Z0/?ref=app
https://code.sololearn.com/ckOirMHWK8Z0/?ref=app

Answer 1

pattern1 and pattern2 will only match strings ending with an 'e' since the $ is not escaped.

pattern3 matches string1 since the escaped $ matches a literal '#x27;

pattern4 matches string2 because the escaped \ followed by an escaped $ matches the literal '\#x27;

Answer 2

that makes sense now. thanks.