Number of items in a List<string> that contain the word "blue"?

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        List carColors = new List { "blue car", "red car", "blue sky", "green car" };

        int count = carColors.Count(color => color.Contains("blue"));
        Console.WriteLine(count); // This will output the count of items containing the word "blue"
    }
}

You can count the number of items in a List that contain the word "blue" using LINQ's Count method along with a lambda expression. For example:

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        List listCarColors = new List()
        {
            "blue",
            "green",
            "blueish",
            "dark blue",
            "lightblue",
            "red"
        };

        int count = listCarColors.Count(color => color.Contains("blue"));

        Console.WriteLine($"Number of items containing 'blue': {count}");
    }
}

Please check this one,

Add linq reference,

using System.Linq;

List liststCarColors = new List { "red", "blue", "green", "blue", "yellow", "blue" };

var count = liststCarColors.Count(x => x.Contains("blue"));

If you are doing wildcard matching, then please use this snippet 

int count = itemList.Count(item => item.Contains("blue"));

if you are looking exact match then please follow the below snippet

int count = itemList.Count(item => item == "blue");