How to Find List Item that is Present in a String

Question

I have to find whether the String Contains one of the Exact word which are present in the List. Eg:

List<string> KeyWords = new List<string>(){"Test","Re Test","ACK"};
String s1 = "Please give the Test"
String s2 = "Please give Re Test"
String s3 = "Acknowledge my work"

Now, When I use: Keywords.Where(x=>x.Contains(s1)) It Gives me a Match which is correct. But for s3 it should not.

Any workaround for this.

Answer 1

Use split function on the basis of space and match the words. i hope that will worked.

Answer 2

How about using regular expressions?

public static class Program
{
    public static void Main(string[] args)
    {
        var keywords = new List<string>() { "Test", "Re Test", "ACK" };
        var targets = new[] {
            "Please give the Test",
            "Please give Re Test",
            "Acknowledge my work"
        };

        foreach (var target in targets)
        {
            Console.WriteLine($"{target}: {AnyMatches(target, keywords)}");
        }

        Console.ReadKey();
    }

    private static bool AnyMatches(string target, IEnumerable<string> keywords)
    {
        foreach (var keyword in keywords)
        {
            var regex = new Regex($"\\b{Regex.Escape(keyword)}\\b", RegexOptions.IgnoreCase);

            if (regex.IsMatch(target))
                return true;
        }

        return false;
    }
}

Creating the regular expression always on-the-fly is maybe not the best option in production, so you should think of creating a list of Regex based on your keywords instead of storing only the keywords in a dumb string list.

Answer 3

Your usage of Contains is backwards:

var foundKW = KeyWords.Where(kw => s1.Contains(kw)).ToList();

Answer 4

Bit different solution.

void Main()
{
    var KeyWords = new List<string>(){ "Test","Re Test","ACK" };
    
    var array = new string[] {
        "Please give the Test",
        "Please give Re Test",
        "Acknowledge my work"
    };
            
    foreach(var c in array)
    {
        Contains(c,KeyWords); // Your result.
    }
}

private bool Contains(string sentence, List<string> keywords) {
        var result = keywords.Select(keyWord=>{
            var parts3 = Regex.Split(sentence, keyWord, RegexOptions.IgnoreCase).Where(x=>!string.IsNullOrWhiteSpace(x)).First().Split((char[])null); // Split by the keywords and get the rest of the words splitted by empty space
            var splitted = sentence.Split((char[])null); // split the original string.
            
            return parts3.Where(t=>!string.IsNullOrWhiteSpace(t)).All(x=>splitted.Any(t=>t.Trim().Equals(x.Trim(),StringComparison.InvariantCultureIgnoreCase)));
        }); // Check if all remaining words from parts3 are inside the existing splitted string, thus verifying if full words.
        return result.All(x=>x);// if everything matches then it was a match on full word.
}

The Idea is to split by the word you are looking for e.g Split by ACK and then see if the remaining words are matched by words splitted inside the original string, if the remaining match that means there was a word match and thus a true. If it is a part split meaning a sub string was taken out, then words wont match and thus result will be false.

Answer 5

how about the using of regex

using \bthe\b, \b represents a word boundary delimiter.

List<string> KeyWords = new List<string>(){"Test","Re Test","ACK"};
String s1 = "Please give the Test"
String s2 = "Please give Re Test"
String s3 = "Acknowledge my work"
bool result = false ;
foreach(string str in KeyWords)
    {
      result = Regex.IsMatch(s1 , @"\b"+str +"\b"); 
      if(result)
         break; 
    }