How to exclude a specific string constant?
You have to use a negative lookahead assertion. You could for example use the following. If this does not work in your editor, try this. It is tested to work in ruby and javascript:
regex
Negative matching using grep (match lines that do not contain foo)
grep -v is your friend: -v, –invert-match select non-matching lines Also check out the related -L (the complement of -l). -L, –files-without-match only print FILE names containing no match
Range of valid character for a base 64 encoding
I am interested in the following:Is there a list of characters that would never occur as part of a base 64 encoded string?For example *. I am not sure if this would occur or not. If the original input actually had * as part of it would that be encoded differently?
Regex for numbers only
Use the beginning and end anchors. Use “^\d+$” if you need to match more than one digit. Note that “\d” will match [0-9] and other digit characters like the Eastern Arabic numerals ٠١٢٣٤٥٦٧٨٩. Use “^[0-9]+$” to restrict matches to just the Arabic numerals 0 – 9. If you need to include any numeric representations other than just digits (like decimal values for starters), then … Read more
Regex Explanation ^.*$ [duplicate]
^ matches position just before the first character of the string $ matches position just after the last character of the string . matches a single character. Does not matter what character it is, except newline * matches preceding match zero or more times So, ^.*$ means – match, from beginning to end, any character that appears zero or more times. … Read more
RegExp in TypeScript
I think you want to test your RegExp in TypeScript, so you have to do like this: You should read MDN Reference – RegExp, the RegExp object accepts two parameters pattern and flags which is nullable(can be omitted/undefined). To test your regex you have to use the .test() method, not passing the string you want to test inside the declaration of your RegExp! Why test + “”? Because alert() in … Read more
How can I match a string with a regex in Bash?
To match regexes you need to use the =~ operator. Try this: Alternatively, you can use wildcards (instead of regexes) with the == operator: If portability is not a concern, I recommend using [[ instead of [ or test as it is safer and more powerful. See What is the difference between test, [ and [[ ? for details.
How can I write a regex which matches non greedy?
The non-greedy ? works perfectly fine. It’s just that you need to select dot matches all option in the regex engines (regexpal, the engine you used, also has this option) you are testing with. This is because, regex engines generally don’t match line breaks when you use .. You need to tell them explicitly that you want to match line-breaks … Read more
Python re.split() vs split()
re.split is expected to be slower, as the usage of regular expressions incurs some overhead. Of course if you are splitting on a constant string, there is no point in using re.split().
Which regular expression operator means ‘Don’t’ match this character?
You can use negated character classes to exclude certain characters: for example [^abcde] will match anything but a,b,c,d,e characters. Instead of specifying all the characters literally, you can use shorthands inside character classes: [\w] (lowercase) will match any “word character” (letter, numbers and underscore), [\W] (uppercase) will match anything but word characters; similarly, [\d] will match the 0-9 digits while [\D] matches anything but the 0-9 digits, … Read more