Count number of matches from a list words in a string

Question

I have a list of words

var words = List<string> { "Apple", "Banana", "Cherry" };'

and a string

var fruitString = "Apple Orange Banana Plum";

I know if I do

var hasFruits = words.Contains(w => fruitString.Contains(w));

that I can tell if the string contains any of those words. What I need to do is tell how many of those words match.

I know that I can do

var count = 0;
foreach (var word in words)
{
    if (fruitString.Contains(word))
    {
        count++;
    }
}

but is there a way of doing this in a Linq one-liner?

Answer 1

Yes, simply swap Contains for Count :

var count = words.Count(w => fruitString.Contains(w));

Note that this retains the same result as your original code - as pointed out in Sergey's answer , this approach may be naive, depending on what you're trying to achieve.

Answer 2

If you want to check count of words which appear in string separated by whitespaces, you can use intersection of sets:

fruitString.Split().Intersect(words).Count() // 2

If you want to check which words your string have - just remove Count call:

fruitString.Split().Intersect(words) // "Apple", "Banana"

---

Note1: if you do String.Contains then "Apple" will be found in "Applejack" string

Note2: passing StringComparer.InvariantCultureIgnoreCase as second argument to Intersect method call will make ignore case string comparison and "apple" will match "Apple".

Note3: you can use Regex.Split to get words from string which has not only white spaces between words. Eg for something like "I look to the east and see: apple, orange and banana!"