I try to create a regex to match lower and uppercase of A-Z, digits and ##$_ symbols with length limit of 4 to 16 for all of string.
My useless regex:
/^([a-zA-Z])|(\d)|(##\$_){4,16}$/
I test Online regex generators Like http://www.jslab.dk/tools.regex.php but don't have a good result .
Your regex /^([a-zA-Z])|(\d)|(##\$_){4,16}$/ matches for a single letter OR a single digit OR 4 to 16 characters of "##\$_".
The groups around the alternatives are useless.
One solution would be to make a group around the whole alternation
/^([a-zA-Z]|\d|##\$_){4,16}$/
but the better solution would be to add everything to one character class
/^[a-zA-Z##$_\d]{4,16}$/
See it here on Regexr
you can maybe simplify it further, since [a-zA-Z\d_] is the same than \w, when \w is not unicode based!
/^[\w##$]{4,16}$/
\w includes lowercase and UPPERCASE letters, digits and the _ character
RegEx Pattern: ^[\w#\#\$]{4,16}$
Explained demo here: http://regex101.com/r/rK1yH2
The expression that you need is this one:
( ([a-zA-Z])|(\d)|(##\$_) ){4,6}
The problem that you have in yours is that the last {2,6} are affecting only to the last group of brackets, not to the whole expression. Also make sure that the "/^" and "$/" are mandatory for your case, because the "^" means "not", so I'm not sure why you have it there.
You can also see it graphically here: http://www.debuggex.com/
Related
I'm trying to create a regular expression that matches strings with:
19 to 90 characters
symbols
at least 2 uppercase alphabetical characters
lowercase alphabetical characters
no spaces
I already know that for the size and space exclusion the regex would be:
^[^ ]{19,90}$
And I know that this one will match any a string with at least 2 uppercase characters:
^(.*?[A-Z]){2,}.*$
What I don't know is how to combine them. There is no context for the strings.
Edit: I forgot to say that it is better ifthe regex excludes strings that finish with a .com or .jpeg or .png or any .something (that "something" being of 2-5 characters).
This regex should do what you want.
^(?=(?:\w*\W+)+\w*$)(?=(?:\S*?[A-Z]){2,}\S*?$)(?=(?:\S*?[a-z])+\S*?$)(?!.*?\.\w{2,5}$).{19,90}$
Basically it uses three positive lookaheads and a negative lookahead to guarantee the conditions that you specified:
(?=(?:\w*\W+)+\w*$)
ensures that there is at least one non-word (symbol) character
(?=(?:\S*?[A-Z]){2,}\S*?$)
ensures that there are at least two uppercase characters, and also excludes a match if there are any spaces in the string
(?=(?:\S*?[a-z])+\S*?$)
ensures that there is at least one lowercase character in the string. The negative lookahead
(?!.*?\.\w{2,5}$)
ensures that strings that end with a . and 2-5 characters are excluded
Finally,
.{19.90}
performs the actual match and ensures that there are between 19 and 90 characters.
Following your requrements, I suggest to use the following pattern:
^(?=.*[a-z])(?=.*[A-Z].*[A-Z])(?=.*[^\s]).{19,90}$
Demo
Instead of just excluding spaces, I used \ssince you probably don't want allow tabs, newlines, etc. either. However, it is still unclear which symbols you want to allow, e.g. [a-zA-Z!"§$%&\/()=?+]
^(?=.*[a-z])(?=.*[A-Z].*[A-Z])(?=.*[^\s])(?=[a-zA-Z!"§$%&\/()=?+]).{19,90}$
To match your additional requirement not to match file-like extensions at the end of the string, add a negative look-ahead: (?!.*\.\w{2,5}$)
^(?=.*[a-z])(?=.*[A-Z].*[A-Z])(?=.*[^\s])(?=[a-zA-Z!"§$%&\/()=?+]).{19,90}$
Demo2
You can use backreferences as described here: https://www.ocpsoft.org/tutorials/regular-expressions/and-in-regex/
Another reference with examples here: https://www.regular-expressions.info/refcapture.html
I really don't use RegEx that much. You could say I am RegEx n00b. I have been working on this issue for a half a day.
I am trying to write a pattern that looks backward from a number character. For example:
1. bob1 => bob
2. cat3 => cat
3. Mary34 => Mary
So far I have this (?![A-Z][a-z]{1,})([A-Za-z_])
It only matches for individual characters, I want all the characters before the number character. I tried to add the ^ and $ into my pattern and using an online simulator. I am unsure where to put the ^ and $.
NOTE: I am using RegEx for the .NET Framework
You may use a regex like
[\p{L}_]+(?=\d)
or
[\w-[\d]]+(?=\d)
See the regex demo
Pattern details
[\p{L}_]+ - any 1 or more letters (both lower- and uppercase) and/or _
OR
[\w-[\d]]+ - 1 or more word chars except digits (the -[] inside a character class is a character class subtraction construct)
(?=\d) - a positive lookahead that requires a digit to appear immediately to the right of the current location
If we break down your RegEx, we see:
(?![A-Z][a-z]{1,}) which says "look ahead to find a string that is NOT one uppercase letter followed one or more lowercase letters" and ([A-Za-z_]) which says "match one letter or underscore". This should end up matching any single lowercase letter.
If I understand what you want to achieve, then you want all of the letters before a number. I would write something like that as:
\b([a-zA-Z]+)[0-9]
This will start at a word boundary \b, match one or more letters, and require a digit right after the matched string.
(The syntax I used seems to match this document about .NET RegEx: https://learn.microsoft.com/en-us/dotnet/standard/base-types/regular-expressions)
In light of Wiktor Stribizew's comment, here is a pure match RegEx:
\b[a-zA-Z_]+(?=[0-9])
This matches the pattern and then looks ahead for the digit. This is better than my first lookahead attempt. (Thank you Wiktor.)
http://www.rexegg.com/regex-lookarounds.html
I am looking to clean up a regular expression which matches 2 or more characters at a time in a sequence. I have made one which works, but I was looking for something shorter, if possible.
Currently, it looks like this for every character that I want to search for:
([A]{2,}|[B]{2,}|[C]{2,}|[D]{2,}|[E]{2,}|...)*
Example input:
AABBBBBBCCCCAAAAAADD
See this question, which I think was asking the same thing you are asking. You want to write a regex that will match 2 or more of the same character. Let's say the characters you are looking for are just capital letters, [A-Z]. You can do this by matching one character in that set and grouping it by putting it in parentheses, then matching that group using the reference \1 and saying you want two or more of that "group" (which is really just the one character that it matched).
([A-Z])\1{1,}
The reason it's {1,} and not {2,} is that the first character was already matched by the set [A-Z].
Not sure I understand your needs but, how about:
[A-E]{2,}
This is the same as yours but shorter.
But if you want multiple occurrences of each letter:
(?:([A-Z])\1+)+
where ([A-Z]) matches one capital letter and store it in group 1
\1 is a backreference that repeats group 1
+ assume that are one or more repetition
Finally it matches strings like the one you've given: AABBBBBBCCCCAAAAAADD
To be sure there're no other characters in the string, you have to anchor the regex:
^(?:([A-Z])\1+)+$
And, if you wnat to match case insensitive:
^(?i)(?:([A-Z])\1+)+$
What is the difference between search pattern like [a-zA-Z][a-zA-Z]* and [a-zA-Z]* ?
The first matches one [a-zA-Z] followed by zero or more [a-zA-Z].
The second matches zero or more [a-zA-Z].
The first can also be written as [a-zA-Z]+.
The regex [a-zA-Z][a-zA-Z]* means that you are mandating that there should be one alpabetic character optionally followed by any number of alphabets. On the other hand, [a-zA-Z]* means that the alphabet mandate is entirely off.
For example, your first regex matches the strings azxxx, abccdef but fails 2abcd, 22 and blank strings. But the second regex can match a blank string too.
For the first regex, you may just want to say: [a-zA-Z]+ instead.
I need to write a regular expression which should not allow any digits. it should allow any other characters except digits. I tried expression like :- ~[0-9]+
but it restricts everything. could you pls help me?
It is not clear what flavor of regex you need, but in the general, one of the following should work:
^[^0-9]*$
^[^\d]*$
^\D*$
^[[:^digit:]]*$
^\P{IsDigit}*$
The last two forms will work with Unicode digits.
The atom [^0-9] matches anything but a digit; to make sure that in the whole string there are no digits, I added the markers of string start (^) and end ($).
If you want to match any part of a string that contains at least one character that is not a digit, replace the ^...*$ part of the regex by ...+:
[^0-9]+
\D+
etc.
Try [^0-9]+. Note that this will only prevent ASCII digits from appearing, not unicode ones.