What is the purpose of the "into" keyword in LINQ?

 In LINQ (Language-Integrated Query), the "into" keyword is used to introduce a new range variable in a query expression. It is typically used to perform additional operations on the results of a previous query or to create a new sequence based on the results of a query.

The "into" keyword allows you to define a new range variable that represents the results of a query expression up to a specific point. It allows you to continue working with the intermediate results without having to repeat the entire query or store the results in a temporary variable.

Here's an example to illustrate the usage of the "into" keyword in LINQ:

var numbers = new List<int> { 1, 2, 3, 4, 5 };

var query = from num in numbers
            where num % 2 == 0
            select num into evenNum
            where evenNum > 2
            select evenNum * 2;

foreach (var result in query)
{
    Console.WriteLine(result);
}

In the above example, we start with a list of numbers. The first query filters the even numbers from the list using the "where" clause. Then, the "into" keyword is used to create a new range variable called evenNum, which represents the even numbers from the previous query.

After that, another "where" clause is applied to further filter the even numbers greater than 2, and finally, the selected even numbers are multiplied by 2 in the "select" clause. The foreach loop then iterates over the final query results and prints them.

By using the "into" keyword, we are able to work with the intermediate results of the query without repeating the initial filtering step. It provides a way to chain multiple query operations together, making the code more concise and readable.