Replacement Expression Nuance With Sub-expressions

[kengrubb]

I'm doing some data cleansing with WE, but I ran into the same Regex issue with TP.

I'm changing dates in a text qualified CSV file from DDMMMYYYY ("22Jan2014") to YYYYMMDD ("20140122").

This Regex Replace did not work.

Find what: (")(\d{2})(Jan)(\d{4})(")
Replace with: $1$401$2$5

[X] Regular expression

Replace All

I'm guessing TextPad is determining, "There aren't 401 sub-expressions. PICNIC."

This Regex Replace worked.

Find what: (")(\d{2})(Jan)(\d{4})(")
Replace with: $1$4\x30\x31$2$5

[X] Regular expression

Replace All

This Regex Replace also worked, and I find it easier to read.

Find what: (")(\d{2})(Jan)(\d{4})(")
Replace with: ${1}${4}01${2}${5}

[X] Regular expression

Replace All

If you're following along, and you need this for something, this only fixed the January dates. I had to rinse and repeat for the other 11 months.

[ben_josephs]

To bind the the 4 but not the following digits to the $ either enclose the index in braces:
${4}
or use parentheses to group subexpressions in the normal way:
($4)

To make all your substitutions in a single step, use conditional replacement expressions:

Find what: (?<=\d{2})(?:(JAN)|(FEB)|(MAR)|(APR)|(MAY)|(JUN)|(JUL)|(AUG)|(SEP)|(OCT)|(NOV)|(DEC))(?=\d{4})
Replace with: ?1(01):?2(02):?3(03):?4(04):?5(05):?6(06):?7(07):?8(08):?9(09):?10(10):?11(11):?12(12)

But you're unlikely to bother to do this unless you're going to do this sort of thing often.

Edit: Made minor corrections.

[kengrubb]

Oh that is just TOO wickedly cool not to use from time to time.