This post is a long-format reply to Jonathan Jordan's recent post. Jonathan's post was about the non-capturing backreference in Regular Expressions. He and I are both working a lot in Behatwhich relies heavily on regular expressions to map human-like sentences to PHP code.
One of the common patterns in that space is the quoted-string, which is a fantastic context in which to discuss the backreference and also introduce lookarounds. Please read hist post first, as from here on the tone and perspective of this post is reply-oriented.
In Behat, this non-capturing groups is helpful to not pollute your step-definition arguments with certain groups that improve the usability of your step but don't change how it behaves.
For example, you can offer steps a choice between "click" and "press" with? But it's worth noting that what you're discussing here? It's a way to group things and tell the engine that you don't need to refer back to what was consumed by the group.
Behat doesn't often use the real notion of backreferences: re-using the captured group as part of the matching requirements. You showed an example snippet used often in Behat's Mink extension:. However, I think this pattern, while clean, is lackluster in that it doesn't support single quotes. What a great opportunity to explore how useful backreferences can be! Basically, we can use a capturing group's backreference to tell the Regex engine that a string should end with the same quote character that started it.
This will feel a bit complicated at first, but we'll break it down. Here is my proposed replacement pattern:. Store that match in a way that I can reference later. Continue matching ANY characters Once you stop matching because the next character is followed by the ending quote, match that last character. This is our opening chunk, which essentially matches any single or double quote, unless that quote is preceded by a backslash. That's a "Negative Lookbehind", and the?
If we didn't care to be careful about erroneously matching escaped quotes, it could simply be this:. Next we want to match any string until we encounter an un-escaped quote, but it must be the SAME e. This is where backreferences come in we need to reference what was matched at the start in order to tell the engine what to look for. We also need a way to say "anything except", but it's not a character class, so we need negative lookahead for this.
The basic algorithm is to keep matching characters as long as they are not followed by the same quote that was used to start the string. Here is the simplified version e. We can break this down even further. I'll strip out some of the parens for readability; they are essentially to manage what gets captured in the end.
The following will match ANY single character that is not followed by the string matched in the first backreference. The next important thing to realize is that the last character before the ending quote will not get matched. That's why we add the last.? Finally, the whole "interesting" part is wrapped up the the necessary parentheses to capture it.
In case it helps cut through the complexity, here's a comparison of "escaping quotes is not supported" and the "escaping quotes works" version. It's probably worth noting that one reason this may be avoided by the community is that the captured results include a group just for the opening quote.
I would like to extract a string that has a single qoutes at the beginning and end like the 'mystring' how would I go about getting the mystring to appear? Thanks in Advance for any help. Oct 9 ' Post Reply. Share this Question. This is a really simple thing to do, apparently you are a real newbie to programming. Replace "'", "". Thanks in Advance for any help To extract mystring from the 'mystring' in the lines above you typically use RegEx expressions.
Calling match. NextMatch will give you 'orange' etc. Substring start, end - start ; But this method may cause exceptions if you are missing a ' -- Happy Coding! Sorry about that. I am indeed a newbie to programming and I started the preface my question with an apology letting everyone know that my brain is not functioning properly due to that I am under the weather.
The effects of the benadryle and cough medicine have me drowsy and sluggish. Sorry for my laziness. This was exactly what I was looking for because my string was containing text before my delimiters and all I needed was what was between my delimiters. Many Thanks.
This discussion thread is closed Start new discussion. Similar topics Detecting NewLine characters in a string. Single versus Double quote marks as string delimiters. Question stats viewed: replies: 4 date asked: Oct 9 '08 Follow this discussion. Follow us to get the Latest Bytes Updates.
Thanks in Advance for any help Oct 9 '08 Post Reply. Replace "'", "" ; Oct 9 'Need support for your remote team? Check out our new promo! IT issues often require a personalized solution. Why EE? Get Access. Log In. Web Dev. NET App Servers. We help IT Professionals succeed at work.
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Jacob Lepley asked. Medium Priority. Last Modified: I am using textpad and need to delete everything within quotes like below. Start Free Trial. View Solution Only.
NVIT End-user support. Commented: Not the solution you were looking for? Getting a personalized solution is easy. Ask the Experts. Author Commented: Thanks for the response. I am getting cannot find regular expression. Please see screen shot. Move your cursor to the top of the file. Then try again. Configure, Preferences, Editor. Dan Craciun IT Consultant.
HTH, Dan. This solution combined with Configure, Preferences, Editor. Thank you so much.RegEx 109- Three ways to Escape double quotes in an AutoHotkey Regular Expression
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Open Mobile Search. Trial software. You are now following this question You will see updates in your activity feed. You may receive emails, depending on your notification preferences. Extract only text between quotes of a string. Kirk woellert on 1 Mar Vote 0. Edited: John Kelly on 26 Feb Accepted Answer: Walter Roberson.
Folks, could use an assist. Desire only the literal text between quotes for this string:. When I return the argument from my readtext file function, and print using disp imtI get this:. When I only want:. I assume the single quotes are associated with the disp function?If you are looking for a quick way to select everything between matching brackets or quotes in VSCode, the following VSCode tips are for you.
This will grow your selection and smartly select everything between the matching brackets or quotes. If you press this keyboard shortcut multiple times your selection will grow to the next matching brackets or tag. The build in keyboard shortcuts are great but if you want even more control over your selection checkout the Quick and Simple Text Selection extension by David Bankier.
What I like the most about this extension is the ability to choose everything inside of a single quotes, double quotes, back ticks, brackets, square brackets or tag with a single keyboard shortcut. What can be done by repeating the build in shortcut can be done with a single keyboard shortcut using this extension. Install Extension. This is remind me of vim. Hello, thank you very much, I was looking for something like that a long time ago. How very grateful.
Your email address will not be published. This site uses Akismet to reduce spam. Learn how your comment data is processed. Do you use any other extensions that lets you to quickly select code in VSCode?
Let me know in the comments below. Sign up to receive my future tutorials and demos straight to your inbox. Now check your email to confirm your subscription. There was an error submitting your subscription. Please try again. Email Address. Vim Lovers 5. Lenin Zapata 5. Very useful. Leave a Reply Cancel reply Your email address will not be published.MatchCollection: This is populated from the pattern specified. We use parentheses to indicate we want to capture values within quotes. Question mark: This means to be conservative, not greedy.
We don't want to capture multiple fields within one set of quotes. Array: The string array is useful if you want to copy the fields to a new array. This way, we turn the groups into an array, similar to how Split works. C Regex. Matches Quote Example Use the Regex. Matches method on quoted string data. Extract quoted string values. Matches, quote. Strings sometimes have quoted values. It is often useful to extract these values. This helps parse text or code such as SQL statements.
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What regex will return the values enclosed in the quotation marks e. Foo Bar and Another Value? For those who want a deeper explanation of how this works, here's an explanation from user ephemient :. Then, you use a language-specific mechanism to extract the matched text. Lets see two efficient ways that deal with escaped quotes. These patterns are not designed to be concise nor aesthetic, but to be efficient.
These ways use the first character discrimination to quickly find quotes in the string without the cost of an alternation. The idea is to discard quickly characters that are not quotes without to test the two branches of the alternation.
You can choose too that a quoted part can be an opening quote until the next non-escaped quote or the end of the string. In this case there is no need to use possessive quantifiers, you only need to make the last quote optional. Notice: sometimes quotes are not escaped with a backslash but by repeating the quote.
Quick Tip - PowerShell Regex To Get Value Between Quotation Marks
The patterns avoid the use of a capture group and a backreference I mean something like ["'] The way this pattern is written is totally "hand-driven" and doesn't take account of eventual engine internal optimizations. Peculiarly, none of these answers produce a regex where the returned match is the text inside the quotes, which is what is asked for.
MA-Madden tries but only gets the inside match as a captured group rather than the whole match. One way to actually do it would be :.