Difference between regex quantifiers plus and star

Question

I try to extract the error number from strings like \"Wrong parameters - Error 1356\":

 Pattern p = Pattern.compile(\"(\\\\d*)\");
 Matcher m =          


        

Answer 1

but none if necessary means that it will not break the regex pattern if there is no match. So \d* means it will match zero or more occurrences of digits.

For eg.

\d*[a-z]*

will match

abcdef

but \d+[a-z]*

will not match

abcdef

because \d+ implies that at least one digit is required.