Regular Expressions 101

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`
(.*)(<a href=")([A-z0-9-\/]+)(".*)
`
gm
1st Capturing Group
(.*)
.
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)
2nd Capturing Group
(<a href=")
<a href="
matches the characters <a href=" literally (case sensitive)
3rd Capturing Group
([A-z0-9-\/]+)
Match a single character present in the list below
[A-z0-9-\/]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-z matches a single character in the range between A (index 65) and z (index 122) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
- matches the character - with index 4510 (2D16 or 558) 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!
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
4th Capturing Group
(".*)
" matches the character " with index 3410 (2216 or 428) literally (case sensitive)
.
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)
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.

Regular Expression
No Match

`
`
gm

Test String