CODEWITHSUNDEEP
c#regex
rajeemcariazo
rajeemcariazo

Reputation: 2524

Replace Contiguous Instance of a String in C#

How can I replace contiguous substring of a string in C#? For example, the string

"<p>The&nbsp;&nbsp;&nbsp;quick&nbsp;&nbsp;&nbsp;fox</p>"

will be converted to

"<p>The&nbsp;quick&nbsp;fox</p>"

Upvotes: 2

Views: 295

Answers (3)

schnaader
schnaader

Reputation: 49719

Let's call the original string s and the substring subString:

    var s = "<p>The&nbsp;&nbsp;&nbsp;quick&nbsp;&nbsp;&nbsp;fox</p>";
    var subString = "&nbsp;";

I'd prefer this instead of a regex, much more readable:

    var subStringTwice = subString + subString;

    while (s.Contains(subStringTwice))
    {
        s = s.Replace(subStringTwice, subString);
    }

Another possible solution with better performance:

    var elements = s.Split(new []{subString}, StringSplitOptions.RemoveEmptyEntries);
    s = string.Join(subString, elements);
    // This part is only needed when subString can appear at the start or the end of s
    if (result != "")
    {
        if (s.StartsWith(subString)) result = subString + result;
        if (s.EndsWith(subString)) result = result + subString;                
    }

Upvotes: 2

Jonny 5
Jonny 5

Reputation: 12389

Maybe this simple one is enough:

(&nbsp;){2,}

and replace with $1 (&nbsp; that's captured in first parenthesized group)

See test at regex101

To check, if a substring is followed by itself, also can use a lookahead:

(?:(&nbsp;)(?=\1))+

and replace with empty. See test at regex101.com

Upvotes: 2

Avinash Raj
Avinash Raj

Reputation: 174706

Use the below regex 

@"(.+)\1+"

(.+) captures the group of characters and matches also the following \1+ one or more same set of characters.

And then replace the match with $1

DEMO

string result = Regex.Replace(str, @"(.+)\1+", "$1");

Upvotes: 3

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