LINQ interview questions part 3

In this post, we will do a quick review of LINQ operators Any() and All().

Question 1: Using LINQ, determine if any word in a list contains the substring “ei”.

    string[] words = { "believe", "relief", "receipt", "field" };

    bool iAfterE = words.Any(w => w.Contains("ei"));

    Console.WriteLine("list has words that contains 'ei': {0}", iAfterE);

Question 2: Using LINQ, return a grouped list of products only for categories that have at least one product that is out of stock.

In this case, we run any over a grouping as shown below:

    List<Product> products = GetProductList();

    var productGroups =

        from p in products

        group p by p.Category into g

        where g.Any(p => p.UnitsInStock == 0)

        select new { Category = g.Key, Products = g };

Question 3: Determine if an array of numbers contains all odds.

int[] numbers = { 1, 11, 3, 19, 41, 65, 19 };

bool onlyOdd = numbers.All(n => n % 2 == 1);

Console.WriteLine("The list contains only odd numbers: {0}", onlyOdd);

Question 4: Using LINQ, return a grouped list of products only for categories that have all of their products in stock.

    List<Product> products = GetProductList();

    var productGroups =

        from p in products

        group p by p.Category into g

        where g.All(p => p.UnitsInStock > 0)

        select new { Category = g.Key, Products = g };