Using linq to count substrings in a string?

Question

I could use the following linq expression to count the number of occurrences of a word as follows:

string test = "And And And";
int j = test.Split(' ').Count(x => x.Contains("And"));

However what if I was searching for "And And", Is there a way to use linq to count words without using split. Do any of these methods take longer the O(n)?

Answer 1

You can use a regular expression:

string test = "And And And";
int j = Regex.Matches(test, "And").Cast<Match>().Count();

BTW, do you want to allow overlapping occurrences? i.e. if you're looking for "And And", do you consider that test contains 1 or 2 occurrences of it?

Answer 2

I found a clever solution that can be resolved serverside with most LINQ to ORMs:

string search = "foo";
int searchLength = search.Length;

var result = qry.Select(i => new { Object = i, Occurrences = (i.SomeProperty.Length - i.SomeProperty.Replace(search, "").Length) / searchLength });

The idea is to replace the substring by an empty string and then divide the difference in string length by the length of the search term.