Question

What could be the exact Regex.IsMatch expression for

span[class|align|style]

I tried with this one but i am not getting exact expected result

if (!Regex.IsMatch(n.Value, @"span\[.*?style.*?\]", RegexOptions.IgnoreCase))  
    n.Value = Regex.Replace(n.Value, @"(span\[.*?)(\])", "$1" + ValToAdd + "$2");

I am checking if the span contains ‘style’ element, if it is present then ‘style’ will not inserted with ‘span’ and vice-versa.

Any pointers?

Answer 1

You forgot to add | before the ValToAdd.

if (!Regex.IsMatch(n.Value, @"span\[.*?\bstyle\b.*?\]", RegexOptions.IgnoreCase))  
    n.Value = Regex.Replace(n.Value, @"(span\[.*?)\]", "$1|" + ValToAdd + "]");

Also, your first regex would match span[class|align|somestyle]. Use word boundary \b to match whole words. Note that this would still match span[class|align|some-style] as \b matches before and after non-word characters. The following regex would match only those styles that are surrounded by [| or || or |].

@"span\[.*(?<=\||\[)style(?=\||\[).*\]"