I am trying to make a regex to find any element that has a specific class.
For example
<span class = "float">
For which I came up with this:
\s*class\s*=\s*('|")\s*float\s*('|")\s*
But then of course you can have multiple CSS declared
<span class = "float align cssnames">
I am not sure how you would make everything else optional.
Maybe \s*class\s*=\s*('|")[\w\s]*\bfloat\b[\w\s]*('|")\s*?
In between the quotes it looks for float with a word boundary on either side, possibly surrounded by further word characters and/or spaces (i.e. other CSS classes).
This code will look for the class=" and " as a non matched anchor. Then it will take each of the attribute values found and put each of them into a named capture group called Assignements.
Then linq will extract out the just those named capture(s) and then look for a single "Float" item from the captured group and return true or false.
string data = @"<span class = ""float align cssnames"">";
string pattern = @"(?:class\s*=\s*\x22)((?<Assignments>[^\s\x22]+)(?:\s?))+(?:\x22)";
var containsFloat =
Regex.Matches(data, pattern, RegexOptions.Multiline)
.OfType<Match>()
.Select(mt => mt.Groups["Assignments"].Captures
.OfType<Capture>()
.Select(c => c.Value))
.SelectMany(assignments => assignments) // is an IEnumerable<string> = { "float", "align", "cssnames" } at this point
.Any(assignment => assignment == "float"); // True!
Regex rgx = new Regex("\"float.*\"");
Will match "float anything here but ends with the closing quote"
