regex-negation

Easy question this time. I'm trying to test whether or not a string does not contain a character using regular expressions. I thought the expression was of the form "[^ x ]" where x is the character that you don't want to appear, but that doesn't seem to be working. For example, Regex.IsMatch("103","[^0]") and Regex.IsMatch("103&","[^&]") both return true (I would expect false). I started using "[^&]" and thought maybe the & needed to be escaped as \&, but it didn't seem to make a difference. Ideas? I assume it's something small. Also, I'm using .NET, so keep that in mind. Edit1: I found this

The string should not contain SSN or phone number. The regex below does not work, it accepts only xxxxxxxxx format. Should not contain xxx-xx-xxxx or xxx-xxx-xxx or xxxxxxxxx . regex = "^((?!\\d[9]$)|(?!(\\d{3}-?\\d{2}-?\\d{4}$)|(?!(\\d{3}-?\\d{3}-?\\d{3})$)$"; You might try: ^(?!((\\d{9})|(\\d{3}-\\d{2}-\\d{4})|(\\d{3}-\\d{3}-\\d{3}))$).* To explain, if we read the query you provided: ^((?!\\d[9]$)|(?!(\\d{3}-?\\d{2}-?\\d{4}$)|(?!(\\d{3}-?\\d{3}-?\\d{3})$)$ We could read that: is not followed by xxxxxxxxx OR is not followed by xxx-xx-xxxx OR is not followed by xxx-xxx-xxx (in my version at

(?!([^"]*"[^"]*")*[^"]*$), This captures , if it is between "".Lets say the test string is 1 2 3 4 , 5 6 7, 8 9 "10 11 12 , 13 14 15," 16,17,"18,19,"20 21,22 captured will be between 12 and 13 and rest like http://regex101.com/r/rX0dM7/1 Now if i change the same the to (?!(.*?".*?")*[^"]*?$), This captures only the end ,'s between 18 and 19.Something like http://regex101.com/r/hL7uS1/1 Now the question is why is [^"] so different from .*?" . Secondly what is the significance of [^"]*$ as if i remove it nothing gets captured. Conceptually, I think you are not thinking this correctly.

This question already has an answer here: Javascript: negative lookbehind equivalent? 13 answers I have this Regex Expression that works in chrome but doesn't not work in Firefox. SyntaxError: invalid regexp group It has something to do with lookbehinds and Firefox does not support these. I need this to work in Firefox can some one help me convert this so it works in Firefox and filters out the tags as well? return new RegExp(`(?!<|>|/|&amp|_)(?<!</?[^>]*|&[^;]*)(${term})`, 'gi'); }; searchTermsInArray.forEach(term => { if (term.length) { const regexp = this.regexpFormula(term); newQuestion

I want to find out a string in which a particular tag does not occur, such as: <xyz>[\w]+<[^(unwanted)]></xyz> where unwanted will be interpreted as a , d , e , n , t and u . But what I want is a block string. How can I express it in regular expression? I have tried negative lookahead, which doesn't work: <xyz>.+(?!unwanted).+</xyz> <xyz>(?:(?!unwanted).)+</xyz> Matches all chars in <xyz>...</xyz> , but only as long as the expression unwanted doesn't start at any of them. 来源： https://stackoverflow.com/questions/14819125/regular-expression-block-negation