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Regular Expression

Regular Expression

Raj Kumar

6y915Learn iOS Programming

Please provide a regular expression, which will satisfy below requirement.

Do not allow -

For Example

Don't allow -

1) k

2)

3) 1

4) ceK<<<<<

Allow -

1) <

2) k<

3) l>

4) K<

5) )1w<.l

6) d<1b

7) B<,e

8) .kk<<<<<>a

I need a regular expression, to achive my requirement.

5 Replies

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Nikhil Bhojani6y ago
@Mario ok. I thought it will check at start position only. Sorry for the inconvenience.
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Mario Scheeren6y ago
@Nikhil Bhojani I don't see my code allowing "1
The Rule is disallow any string containing a "<" followed by a letter a to z case insensitive.
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Nikhil Bhojani6y ago
@Mario Scheeren Your code will allow 1
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Mario Scheeren6y ago
How about this one?
if (!Regex.IsMatch(dataString, @"<[a-zA-Z]"))
{
  // Line does not contain pattern
}
+2
Nikhil Bhojani6y ago
You can check positive condition like .*?<+[a-zA-Z]+
Where .*? matches any character except line break for occurence of 0 or more times.
<+ will check for there is atleast one or more < sign
[a-zA-Z]+ will check for one or more occurences for a-z or A-Z
If any of the string is satisfying above regex then it is not the string to be considered. For ex Demo

If(regexSatisfied -- .*?<+[a-zA-Z]+)
{
//Here are your "DO NOT ALLOW"strings
}
ELSE
{
//Here are your ALLOWED strings
}

Let me now if it doesn't satisfies criteria. Below is the result from regx comparer site https://www.regextester.com/.Ignore before / and at end /g as it is not required and matching only highlighted as well as i specified above regular expression

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