Using regular expressions in formulas

To use RE, each of these functions requires you to specify the SEARCH::RegEx (or 8192) flag/constant as its parameter as described in the Formula Composer window.

In the Find() function you can also use the SEARCH::RegExStr flag/constant. If it's specified, instead of the index the function returns the substringthat matches the pattern.
For example:

Along with the SEARCH::RegExStr/SEARCH::RegEx options you can also specify which capturing group should be returned:
32 - 1st group, 64 - 2nd group, 128 - the 3rd group.
The example when this is helpful is extracting file folder, name or extension from the full file path:

=find("^(.*[\\\/])?(\.*.*?)(\.[^.]+?|)$", "c:\folder1\file.txt", 1, 32+SEARCH::RegExStr)

=find("^(.*[\\\/])?(\.*.*?)(\.[^.]+?|)$", "c:\file.txt", 1, 64+SEARCH::RegExStr)

abc finds cells containing (substrings) "abc"

.bc finds cells containing three character substrings consisting of any character followed by "bc"

\Aabc cell contents starting with "abc"

abc\z cell contents ending with "abc"

\Aabc.*123\z cell contents starting with "abc" and ending with "123" with any number of other characters in between

abc\d\z substrings ending with "abc" and one digit

^a\d+ cell contents containing a line that starts with "a" and at least one digit

^a\d* cell contents containing a line that starts with "a" and zero or more digits

a\d*$ cell contents containing a line that ends with "a" and zero or more digits

[ab]+c substrings "abc", "aabc", "abbabc" etc. and not "c"

[ab]*c substrings "abc", "aabc", "abbabc" etc. and "c"

[^ab]+c substrings ending with "c" and not containing "a" or "b"

\w\d{2,3} substrings consisting of one letter followed by 2 or 3 digits

^ab\d{2,3}c cell contents beginning with "ab", two or three digits and "c"

abc|xyz cells containing substrings "abc" or "xyz"

The Replace() function additionally accept the replacing string which - if the SEARCH::RegEx flag is set - can contain:

Find pattern:	ab+
Database field content:	abcdefaabb
Replace string:	x
Replacement result:	xcdefax

Find pattern:	(.)a+\d{1,3}
Database field content:	abc aa0102
Replace string:	\1
Replacement result:	abc 2

Find pattern:	(ab)
Database field content:	abcdef ghijk abb123
Replace string:	\u\1\l\1xyz\s
Replacement result:	ABabxyz cdef ghijk ABabxyz b123

Find pattern:	\R
Database field content:	abc def ghi
Replace string:	\s
Replacement result:	abc def ghi

abc	finds cells containing (substrings) "abc"
.bc	finds cells containing three character substrings consisting of any character followed by "bc"
\Aabc	cell contents starting with "abc"
abc\z	cell contents ending with "abc"
\Aabc.*123\z	cell contents starting with "abc" and ending with "123" with any number of other characters in between
abc\d\z	substrings ending with "abc" and one digit
^a\d+	cell contents containing a line that starts with "a" and at least one digit
^a\d*	cell contents containing a line that starts with "a" and zero or more digits
a\d*$	cell contents containing a line that ends with "a" and zero or more digits
[ab]+c	substrings "abc", "aabc", "abbabc" etc. and not "c"
[ab]*c	substrings "abc", "aabc", "abbabc" etc. and "c"
[^ab]+c	substrings ending with "c" and not containing "a" or "b"
\w\d{2,3}	substrings consisting of one letter followed by 2 or 3 digits
^ab\d{2,3}c	cell contents beginning with "ab", two or three digits and "c"
abc\|xyz	cells containing substrings "abc" or "xyz"