Regular Expressions 101

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/
^\D*(?<number>0*(?<nonzeros>\d+))(?<suffix>.*)$
/
gm
^ asserts position at start of a line
\D
matches any character that's not a digit (equivalent to [^0-9])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Named Capture Group number
(?<number>0*(?<nonzeros>\d+))
0
matches the character 0 with index 4810 (3016 or 608) literally (case sensitive)
Named Capture Group nonzeros
(?<nonzeros>\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Named Capture Group suffix
(?<suffix>.*)
.
matches any character (except for line terminators)
* 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 a line
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String