Regular Expressions 101

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/
.*\s([[:digit:]]*)\s(?:of|[\/])\s([[:digit:]]+)
/
gm
.
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)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
1st Capturing Group
([[:digit:]]*)
Match a single character present in the list below
[[:digit:]]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
[:digit:] matches a digit [0-9] (also written as \d)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Non-capturing group
(?:of|[\/])
1st Alternative
of
of
matches the characters of literally (case sensitive)
2nd Alternative
[\/]
Match a single character present in the list below
[\/]
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
2nd Capturing Group
([[:digit:]]+)
Match a single character present in the list below
[[:digit:]]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
[:digit:] matches a digit [0-9] (also written as \d)
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