Regular expression question

Question

I have some text like this:

dagGeneralCodes$_ctl1$_ctl0

Some text

dagGeneralCodes$_ctl2$_ctl0

Some text

dagGeneralCodes$_ctl3$_ctl0

Some text

dagGeneralCodes$_ctl4$_ctl0

Some text

I want to create a regular expression that extracts the last occurrence of dagGeneralCodes$_ctl[number]$_ctl0 from the text above. the result should be: dagGeneralCodes$_ctl4$_ctl0

Thanks in advance
Wael

Answer 1

This should do it:

.*(dagGeneralCodes\$_ctl\d\$_ctl0)

The .* at the front is greedy so initially it will grab the entire input string. It will then backtrack until it finds the last occurrence of the text you want.

Alternatively you can just find all the matches and keep the last one, which is what I'd suggest.

Also, specific advice will probably need to be given depending on what language you're doing this in. In Java, for example, you will need to use DOTALL mode to . matches newlines because ordinarily it doesn't. Other languages call this multiline mode. Javascript has a slightly different workaround for this and so on.

Answer 2

You can use:

[\d\D]*(dagGeneralCodes\$_ctl\d+\$_ctl0)

I'm using [\d\D] instead of . to make it match new-line as well. The * is used in a greedy way so that it will consume all but the last occurrence of dagGeneralCodes$_ctl[number]$_ctl0.

Answer 3

I really like using this Regular Expression Cheatsheet; it's free, a single page, and printed, fits on my cube wall.