What is LINQ

Language Integrated Query (LINQ) is a set of extensions to the .NET Framework that encompass language-integrated query, set, and transform operations. It extends C# and Visual Basic with native language syntax for queries and provides class libraries to take advantage of these capabilities.

Let us see an example first. Suppose there is a list of integers like this:

List<int> list = new List<int>() { 1, 2, 3, 4, 5, 6, 100 };

To find all the even numbers in this list, you might write some code like this:

List<int> list1 = new List<int>();
foreach (var num in list)
{
    if (num % 2 == 0)
        list1.Add(num);
}

Now with LINQ, you can select all of the even numbers from this list and assign the query result to a variable in just one sentence like this:

var list2 = from number in list
            where number % 2 == 0
            select number;

In this example list2 and list1 are equivalent. list2 contains the same numbers as list1 does. As you can see, you...