Regular Expressions 101

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/
(?<=client:)\s*([\w\s\.\-]+),\s*([\w\s\.\-]+)\s*_doc
/
gmi
Positive Lookbehind
(?<=client:)
Assert that the Regex below matches
client:
matches the characters client: 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)
1st Capturing Group
([\w\s\.\-]+)
Match a single character present in the list below
[\w\s\.\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
\. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case insensitive)
, matches the character , with index 4410 (2C16 or 548) 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)
2nd Capturing Group
([\w\s\.\-]+)
Match a single character present in the list below
[\w\s\.\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
\. matches the character . with index 4610 (2E16 or 568) literally (case insensitive)
\- matches the character - with index 4510 (2D16 or 558) 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)
_doc
matches the characters _doc literally (case insensitive)
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)
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

/
/
gmi

Test String