Assume the following class:
class Person
{
public string FirstName {get;set;}
public string LastName {get;set;}
}
Lets say that I have a list or an array of Person object. Is there a way using LINQ to retrieve FirstName property from all the array elements and return an array of string. I have a feeling that I have seen something like that before.
Hope that the question makes sense.
Sure, very easily:
Person[] people = ...;
string[] names = people.Select(x => x.FirstName).ToArray();
Unless you really need the result to be an array though, I'd consider using ToList() instead of ToArray(), and potentially just leaving it as a lazily-evaluated IEnumerable<string> (i.e. just call Select). It depends what you're going to do with the results.
If you have an array, then personally, I'd use:
Person[] people = ...
string[] names = Array.ConvertAll(people, person => person.FirstName);
here; it avoids a few reallocations, and works on more versions of .NET. Likewise:
List<Person> people = ...
List<string> names = people.ConvertAll(person => person.FirstName);
LINQ will work, but isn't actually required here.
Array.ConvertAll in performance-sensitive code, or using .NET 2.0 of course.Try this:
List<Person> people = new List<Person>();
people.Add(new Person()
{
FirstName = "Brandon",
LastName = "Zeider"
});
people.Add(new Person()
{
FirstName = "John",
LastName = "Doe"
});
var firstNameArray = people.Select(p => p.FirstName).ToArray();
