How to query this in LINQ? C#

Considering the following:

public class Person
{
    public Person(string fName, string lName)
    {
        this.firstName = fName;
        this.lastName = lName;
    }

    public string firstName;
    public string lastName;
}

class App
{
    static void Main()
    {
        Person[] peopleArray = new Person[3]
        {
            new Person("John", "Smith"),
            new Person("Jim", "Johns开发者_运维百科on"),
            new Person("Sue", "Rabon"),
        };
        // select lastName from peopleArray where firstName like '%'J'%'
    }
}

Using LINQ, how can express this:

select lastName from peopleArray where firstName like '%'J'%'

I want to print the lastnames of all person having "J" in their firstname. I find it hard to express it in LINQ. Help Please....

var query = from person in peopleArray 
            where person.firstName.Contains("J") 
            select person.lastName;

// or
var query = peopleArray.Where(p => p.firstName.Contains("J")).Select(p => p.lastName);

// use results, print to screen?
foreach (string lastName in query)
{
     Console.WriteLine(lastName);
}

List<string> matchingLastNames = (from person in peopleArray 
                                  where person.firstName.Contains("J") 
                                  select person.lastName).ToList<string>();

I give you some advices. 1.learn what delegate is. 2.learn what lambda expression is. 3.learn extend methods.

if you learn these. you can write anything you like in linq.