Regular Expressions 101

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/
^([0-9]*)(\\*)$
/
^ asserts position at start of the string
1st Capturing Group
([0-9]*)
Match a single character present in the list below
[0-9]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
2nd Capturing Group
(\\*)
\\
matches the character \ with index 9210 (5C16 or 1348) literally (case sensitive)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
$ asserts position at the end of the string, or before the line terminator right at the end of the string (if any)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/

Test String