This question already has answers here:
Java regex throws java.util.regex.PatternSyntaxException: Illegal/unsupported escape sequence for the letter g
(3 answers)
Closed 2 years ago.
I want to built a calculator which accepts numbers like 1E100 or 1.34E-200. In order to check if the number entered is acceptable i decided to test the condition with my regex:
^-?\\d+\\.?\\d*\\E?\\-?\\d*$
however i get an illegal escape and i dont know why? does reges not accept my E?
You escaped the E, which is not necessary :
^(-?\d+\.?\d*E?\-?\d*)$
Test it here
Related
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Exclude characters from a character class
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Character class subtraction, converting from Java syntax to RegexBuddy
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Subtraction in regex doesn't get results
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Javascript regex character exclusion
(4 answers)
Closed 28 days ago.
I would like to know if there's any logical and operators in a regex, for example I want to do something like match a-z and A-Z but not e/E/i/I.
I tried something like
[a-zA-Z]&[^eEiI]
But it's just plain wrong, there's no such operator in any regexes.
But weirdly there's an or operator that can be used within groups like (x|y).
So I was wondering if there's any work around when there's a need to include a logical and condition in regexes.
You have 2 options:
1: Use negative lookahead:
(?![eEiI])[a-zA-Z]
2: Use negated character class and exclude few characters:
[a-df-hj-zA-DF-HJ-Z]
Additionally, if you are using Java as regex flavor then you can use:
[a-zA-Z&&[^eEiI]]
This question already has answers here:
Regular expression for alpahbet,underscore,hyphen,apostrophe only
(5 answers)
Closed 2 years ago.
I want to make a pattern for input.
I have this [A-Za-z]|-, but if I type dsadsa$ this, the special characters still allowed and I need only
big and small letters, and - .
You can escape - character:
[A-Za-z\-]
Your expression should be like following:
([A-Za-z\-]+)
([\w-]+)
This question already has an answer here:
Learning Regular Expressions [closed]
(1 answer)
Closed 2 years ago.
I'm searching for a Regex to avoid letting user to enter a string with only a single ? character.
Here are examples of what I want to achieve:
? Not Ok (I want to avoid letting this)
?a Ok
a? Ok
?? Ok
??? Ok
This matches either any one- character string which is different from ? or any string with at least two characters
^([^?]|..+)$
This question already has answers here:
My regex is matching too much. How do I make it stop? [duplicate]
(5 answers)
How to extract a substring using regex
(14 answers)
Closed 3 years ago.
I'm trying to find the word: <*hasburnt*> in the string below using the this regex: <\*.*(bur).*\*>
But it gives me both <*hasburnt*> <*electrical*>. How do I just get <*hasburnt*> ?
bench testedstarter, starter just makes noise, and <*hasburnt*>
<*electrical*> smell.
Try this: /<.*?(bur).*?>/
Regex101 demo
The reason for ? here is because .* tries to match as much characters as possible, so it also matches <electrical. .*? makes it lazy - trying to match as little as possible, and as such ending the match at <hasburnt>.
EDIT: using ? for the first .* would make <hasburnt> independent of positions of similar strings.
This question already has answers here:
Using regular expressions to validate a numeric range
(11 answers)
Closed 5 years ago.
I'm trying to create a regex string that allows values 0.0 - 5.0. I need the one decimal point to be required. The string below gets me there, but it also allows 5.1-5.9. How do I prevent 5.1-5.9 from being entered, and allow 5.0?
^[0-5]+(\.[0-9]{1})$
Try this regex:
^([0-4]\.[0-9]|5\.0)$
It matches any number from 0 to 4 then dot then any number.
it also matches 5.0
Note: Your regex has another problem that you used + after [0-5] which also matches 55 for example, so you need to remove the +. You also need to remove {1}, It won't make any change but it's useless.