Regex last occurrence


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The question of the day is how to use a regular expression to select the last instance of a word in a string of text. The answer lies in a feature of the regular expression engine called Negative Lookahead. Negative Lookahead is a regular expression lookaround function that belongs to a grouop of functions that do not select matching text.

A negative lookahead lets you match a pattern that is then not followed by another pattern. If we want to match the last instance of the string abcthen we can use a negative lookahead that looks for the text abcand that is not followed by any further abc text.

In a regular expression this is written as:.

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In this expression, the first abc is the pattern to match. Since there are many instances of abc in our example text, we will need a negative lookahead to help us only find the last instance of abc … in other words, the instance of abc where there are no following instances of abc.

This is done using wildcard text matching:. As you can see, this is a straightforward and effective regular expression to match the last occurrence of a string of text. If we want to write a JavaScript function that will take the value of the text input area and change the meaning as an alert to the user, we could write a function to do so. To accomplish this replacement we will need to replace the last instance of the word fox in our string.

I have been playing around with TypeScript and really enjoy the syntax. Notice that the main difference in the example below from the JavaScript in the example above is in assigning types to each variable… the string type is the only type that I use here, but if you are working with typescript you can use: stringnumberboolanyand null. Here is the same example from the JavaScript above, written in TypeScript and outputting to a second text input rather than an alert:. I specialize in Web application development with a focus on building secure systems, integrating applications, and designing robust database structures.

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You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Skip to content Justin Cooney. In a regular expression this is written as: abc?!.

regex last occurrence

Share this: Twitter Pinterest Facebook. Like this: Like Loading Published by Justin Cooney. Thanks for the feedback Marco, I am glad the tips were helpful. Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:. Email required Address never made public.

Name required.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I need to use a regex to replace the last occurrence of the dot with another string like 2x and then the dot again very much like a retina image filename i.

You do not need a regex for this. Matches a literal dot and then asserts? The replacement should include the one dot that was matched, unless you want to remove it. To match all characters from the beginning of the string until and including the last occurence of a character use:. Learn more. RegEx that will match the last occurrence of dot in a string Ask Question. Asked 7 years, 10 months ago. Active 1 year, 3 months ago. Viewed 92k times. I have a filename that can have multiple dots in it and could end with any extension: tro.

Salman A k 73 73 gold badges silver badges bronze badges. Active Oldest Votes. Jon Jon k 65 65 gold badges silver badges bronze badges. That returns an integer of the position where that character is, right? How can I use that integer with. JacksonGariety: You don't need to.

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Cool answer! It's a lot more readable, and little bit faster. Salman A Salman A k 73 73 gold badges silver badges bronze badges. Correctly answers OPs question. Qtax: Not quite, because it won't work if the last dot is also the very last character. Jon, true.

Regex to Replace the Last Occurrence of a Character in Google Sheets

Almost korrect then. I am not sure if a filename could have a. Was a bit hasty with that answer — fixed it to make more sense w. I think you are missing a. I prefer escaping. Not quite. Output should be tro. Not soon I don't want the job, nor have the time. The character.The formulas are based on Regexextract, Substitute, and Regexmatch respectively. But there is no point in extracting nth occurrence of a specific wordright? The above formula is case insensitive.

If you put 4, then the formula would return FALSE as there is no fourth occurrence of the said string. Instead of Regex, I am using the Substitute function to replace the nth occurrence of a string or number in Google Sheets. This formula is case sensitive. We can use the Substitute function in Google Sheets for matching nth occurrence!

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Do you know how? If the above phrase is in cell A1, to extract the second number which is 30 from this, we can use the Regexextract function as follows in Google Sheets.

regex last occurrence

Since Regex is a text function, the returned number, i. Want the Regexextract output in number? Then use this formula. If you simply want the second occurrence of a value irrespective of the value, it can be a number or text then use this Regex. Use the above formulas to meet your requirements of extracting, replacing, and matching the nth occurrence of a value in Google Sheets.

Save my name, email, and website in this browser for the next time I comment. Google Sheets Functions Charts Sheets vs. Excel Docs. Sign in. Log into your account. Forgot your password? Password recovery. Recover your password. Google Sheets. Table of Contents. Please enter your comment! Please enter your name here. You have entered an incorrect email address!By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Because it's negative, it only matches if it does not find a match. Though I'm not sure if one absolutely has to use regexp for the task. Learn more. Regex Last occurrence? Ask Question. Asked 8 years, 4 months ago. Active 1 year, 6 months ago.

Viewed k times. Royi Namir Royi Namir k gold badges silver badges bronze badges. I appreciate that your question pertained to regexes, but are you sure this is the best tool to use here?

Most standard libraries will have a method that will retrieve the last path name in a given directory.

This also takes into account what the directory separator is on a given OS. Raskolnikov I need that in regex.

I know the Pth. OK, fair enough, just making sure. I'll leave it to people more skilled in regexes then. Active Oldest Votes. Your negative lookahead solution would e. The Multi line is only for the Regexr test needed. Standard is end of the string, with Multiline its end of the row. Because the test text in Regexr has multiple rows I need this option there. It also matches the entire string for pathes without any slashes in them e. In a Tempered Greedy Token, the dot should always come after the lookahead:?

One that worked for me was:.

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Jeeter Jeeter 4, 1 1 gold badge 37 37 silver badges 58 58 bronze badges. Turns out the accepted answer above by stema does the job when the backslash is replaced with a forward slash.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

For example, return the part of the string that is after the last x in axxxghdfx should return By default, a quantified subpattern is "greedy", that is, it will match as many times as possible given a particular starting location while still allowing the rest of the pattern to match. Yet another way to do it. It's not as simple as a single regular expression, but if you're optimizing for speed, this approach will probably be faster than anything using regex, including split.

This may substantially slow your program. To avoid this cost while retaining the grouping behaviour, use the extended regular expression "? As of 5. As a workaround for this problem, Perl 5.

The use of these variables incurs no global performance penalty, unlike their punctuation char equivalents, however at the trade-off that you have to tell perl when you want to use them. I would humbly submit that this route is the best and most straight-forward approach in most cases, since it does not require that you do special things with your pattern construction in order to retrieve the postmatch portion, and there is no performance penalty.

Learn more. How can I match everything that is after the last occurrence of some char in a perl regular expression?

Regex Tester

Ask Question. Asked 9 years, 8 months ago. Active 3 months ago. Viewed 21k times. David B David B 25k 43 43 gold badges silver badges bronze badges. Active Oldest Votes.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Which unfortunately selects only 1st occurrence.

The highlighted text is the desired result. It doesn't matter how many square brackets at the end, just need the last array set. This option is exclusive to the. NET regex flavor, and does exactly what you asked for: searches from the end of the input instead of the beginning. Of particular note, the non-greedy? There should be a global flag or a method that returns all matches in your language.

Use this and take the last match. In C Matches returns a MatchCollection containing all found matches. So you can do for example this:.

regex last occurrence

Learn more. Regex get last occurrence of the pattern Ask Question. Asked 7 years, 4 months ago. Active 7 years, 4 months ago. Viewed 20k times. I have a string and I need to select the last occurrence of the pattern. The string is: [[[ Vazgun Vazgun 1 1 gold badge 1 1 silver badge 7 7 bronze badges. Active Oldest Votes. Use the RightToLeft option: Regex. RightToLeft This option is exclusive to the. Alan Moore Alan Moore So simple, yet so unknown. Harry That's the most commonly asked question on Stack Overflow.

Do a greedy match up to the last set of [[ and capture. Chris Seymour Chris Seymour Looks like it works for Ruby. I'm using c and I'm using different website to check regex experssions: regexr. The regex matches the whole string, but the part you're interested in is captured in group 1 in C you would use 'Group[1].

This technique works in every flavor, but. NET also offers a neater option, as my answer explains.

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AlanMoore is correct, generally this is the only way to do it without being able to specify the occurrence which is language specific.

As the question had no reference to C I could only provide the best language agnostic solution, in future be sure to add all relevant information to the question.Using a Regex function you can replace the last occurrence of a character in Google Sheets. Needless to say, you can use the same formula to extract the last occurrence of a word. Sometimes you may want to replace the last occurrence of a character, for example, a colon, semicolon, comma or pipe with another character.

Let me explain that below. If you want to replace the last occurrence of a pipe symbol, then the regular expression will be as follows. Since the Pipe symbol is a regular expression operator, we must use a backslash to escape it. See the regular expression in the above formula to understand it.

Quantifiers in Regular Expressions

In some cases, you may want to replace the last occurrence of a whole word, I mean a string or you can say a text. Save my name, email, and website in this browser for the next time I comment. Google Sheets Functions Charts Sheets vs. Excel Docs. Sign in.

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Log into your account. Forgot your password? Password recovery. Recover your password. Google Sheets. To get the above-expected result 1, use this RegexReplace formula.

Replace Pipe Symbol with a String If you want to replace the last occurrence of a pipe symbol, then the regular expression will be as follows. You can see all the formula 1, 2, and 3 results below.

RegexReplace to Replace the Last Occurrence of a String in Google Sheets In some cases, you may want to replace the last occurrence of a whole word, I mean a string or you can say a text.


comments on “Regex last occurrence

    JoJoshakar

    die sehr schnelle Antwort:)

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