Regular Expressions 101

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/
<a.+?\s*href\s*=\s*["\']?([^"\'\s>]+)["\']?
/
gi
<a
matches the characters <a literally (case insensitive)
.
matches any character (except for line terminators)
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
href
matches the characters href literally (case insensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
= matches the character = with index 6110 (3D16 or 758) literally (case insensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
["\']
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
\' matches the character ' with index 3910 (2716 or 478) literally (case insensitive)
1st Capturing Group
([^"\'\s>]+)
Match a single character not present in the list below
[^"\'\s>]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
\' matches the character ' with index 3910 (2716 or 478) literally (case insensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
> matches the character > with index 6210 (3E16 or 768) literally (case insensitive)
Match a single character present in the list below
["\']
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
\' matches the character ' with index 3910 (2716 or 478) literally (case insensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gi

Test String