Regular Expressions 101

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/
^[^\?#\s]*?(\d{4,7})(?:[^-\w\s]\S*?$|$)$
/
gm
^ asserts position at start of a line
Match a single character not present in the list below
[^\?#\s]*?
*? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\? matches the character ? literally (case sensitive)
# matches the character # literally (case sensitive)
\s matches any whitespace character (equal to [\r\n\t\f\v ])
1st Capturing Group
(\d{4,7})
\d{4,7}
matches a digit (equal to [0-9])
{4,7} Quantifier — Matches between 4 and 7 times, as many times as possible, giving back as needed (greedy)
Non-capturing group
(?:[^-\w\s]\S*?$|$)
1st Alternative
[^-\w\s]\S*?$
Match a single character not present in the list below
[^-\w\s]
- matches the character - literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
\w matches any word character (equal to [a-zA-Z0-9_])
\s matches any whitespace character (equal to [\r\n\t\f\v ])
\S*?
matches any non-whitespace character (equal to [^\r\n\t\f\v ])
*? Quantifier — Matches between zero and unlimited times, as few times as possible, expanding as needed (lazy)
$ asserts position at the end of a line
2nd Alternative
$
$ asserts position at the end of a line
$ 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

Regular Expressions 101

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