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Regular expression to enforce complex passwords, matching 3 out of 4 rules
(4 answers)
Closed 8 years ago.
My password strength criteria is as below :
Character length: 8 -> 24
Contains least 3 of following types:
Uppercase letter [A-Z]
Lowercase letter [a-z]
Numeric [0-9]
Special character ~`!##$%^&*()-_=+[{]}\|;:'"<,>.?/
Can anyone help me to make regular expression and explain. Thanks.
It would be very difficult to do in one regex. Personally, I'd check for each case separately and count if you've got three matches. It would be easier to read and maintain.
So match [A-Z] then [a-z] then [0-9] and finally [~`!##$%^&*()-_=+[{]}\|;:'"<,>.?/]
If you end up with a match in three of the tests that's success.
Use this Regex:
(?=.{8,24})(?=.*\d)(?=.*[A-Za-z])(?=.*[~`!##\$%\^&\*()_=\+[{\]}\|;:'"<,>\.\?/]).*
Debuggex Demo
Related
This question already has answers here:
Regular expression to validate numbers separated by commas or dashes [closed]
(2 answers)
Closed 2 years ago.
I have to write the Regex expression which accepts - and only numbers either single four digit number or two 4 digit numbers seperated by hyphen as shown below
2751, 2759-2764, 2766-2774, 2776-2777, 2890-2897
3945-3974, 3979, 3984-3999
I have used this Regex ^[0-9_,]+ but this line Regex.IsMatch(line, #"^[0-9_,]+$") returns false.
Regards,
Nagasree
The pattern that you tried is not matching as there is no hyphen or space in the character class. But when you would add those, the pattern still does not take any format into account.
You could match 4 digits with optional hyphen and 4 digits part. Then repeat that preceded by a space:
^[0-9]{4}(?:-[0-9]{4})?(?:, [0-9]{4}(?:-[0-9]{4})?)*$
Regex demo
var s = "2751, 2759-2764, 2766-2774, 2776-2777, 2890-2897";
Console.WriteLine(Regex.IsMatch(s, #"^[0-9]{4}(?:-[0-9]{4})?(?:, [0-9]{4}(?:-[0-9]{4})?)*$"));
Output
True
This question already has an answer here:
Learning Regular Expressions [closed]
(1 answer)
Closed 3 years ago.
I'm trying to match only {n} digits not more or less and may be surrounded by characters or special symbols
example:
suppose the {n} = {14}
*12345678901234*300 OK
12345678901234x21 OK
*123456789012345*300 NOT OK
12345678901234 OK
123456789012345 NOT OK
You could use negative lookarounds to assert what is directly on the left and right is not a digit and match 14 digits:
(?<!\d)\d{14}(?!\d)
.NET regex demo
(?:^|\D)(\d{14})(?:\D|$)
Here is a Live Demo
This question already has answers here:
C# Regex to match the word with dot
(3 answers)
Regex plus vs star difference? [duplicate]
(9 answers)
Closed 3 years ago.
I have some validation code that checks a string against a regular expression.
Regex regex = new Regex(RegexPattern);
if (!regex.IsMatch(value))
{
errorMessage = "The data is not in the correct format.";
return false;
}
If I set the regular expression pattern to ^[0-9]*.[0-9]*.[0-9]*.[0-9]*$, it correctly accepts 1.0.0.0; however, it also accepts 1.0.0..
How can I modify the pattern so that 1.0.0.0 is accepted but 1.0.0. is rejected?
[0-9]* means 0 or more occurrence of [0-9]
[0-9]+ means 1 or more occurrence of [0-9]
^[0-9]*.[0-9]*.[0-9]*.[0-9]*$
Change * to +:
^[0-9]+.[0-9]+.[0-9]+.[0-9]+$
Just a slight misunderstanding about * and +. The former accepts either no occurrences or more (>=0), the latter only matches if such vocabulary occurs at least once (>=1).
^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$
I usually also escape the dot for safety, not entirely sure if it's necessary but I still do it. :)
You can use this pattern:
^\d+\.\d+\.\d+\.\d+$
Explanation:
^ - begin of string
\d - any digit
+ - at least one char
\. - exactly a dot char
$ - end of string
By the way, your input looks like an IP address. If so you can modify your reges like this:
^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$
{1,3} means: 'from 1 to 3 chars'
Demo: regex101
To match 4 sets of digits separated by a period
^\d+(?:\.\d+){3}$
This question already has answers here:
Strong password regex [duplicate]
(4 answers)
Closed 8 years ago.
How do I write a regular expression for the following
at least 6 characters
at least 1 uppercase
at least 1 lowercase
at least 1 number
at least 1 special character ("#¤%&/( æøå etc.)
I tried the below regex but it isn't working.
^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[#+-?$!]).{8,}$
Below regex would satisfy all of your conditions,
^(?=.{6,})(?=.*?[A-Z])(?=.*?[a-z])(?=.*?\d)(?=.*?\W).*$
DEMO
(?=.{6,}) at least 6 characters
(?=.*?[A-Z]) at least 1 uppercase
(?=.*?[a-z]) at least 1 lowercase
(?=.*?\d) at least 1 number
(?=.*?\W) at least 1 non-word character
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Reference - What does this regex mean?
(1 answer)
Closed 3 years ago.
I want to make sure a first name field has at least one alphanumeric character and also allow spaces and dashes.
**VALID**
David
Billie Joe
Han-So
**INVALID**
-
Empty is also invalid
To ensure the dashes and spaces happen in legitimate places, use this:
(?i)^[a-z]+(?:[ -]?[a-z]+)*$
See demo.
(?i) puts us in case-insensitive mode
^ ensures we're at the beginning of the string
[a-z]+ matches one or more letters
[ -]?[a-z]+ matches an optional single space or dash followed by letters...
(?:[ -]?[a-z]+)* and this is allowed zero or more times
$ asserts that we have reached the end of the string
You mentioned alphanumeric, so in case you also want to allow digits:
(?i)^[a-z0-9]+(?:[ -]?[a-z0-9]+)*$
use this pattern
^(?=.*[a-zA-Z])[a-zA-Z -]+$
Demo
oh, for alphanumeric use
^(?=.*[a-zA-Z0-9])[a-zA-Z 0-9-]+$