CODEWITHSUNDEEP
collectionsc#-3.0
Rodolfo
Rodolfo

Reputation: 181

C# 3 collection problem

Why in C# 3 I can do this:

 DataTable dt = new DataTable() {
 Columns = { "1", "2", "3" } };

But I can't do this:

 class Person {
    int Id { get; set; }
}
class Program    {
    static void Main(string[] args)
    {
        var v = new List<Person> { 1, 2, 3 };
    }
}

Upvotes: 2

Views: 51

Answers (4)

Jeff
Jeff

Reputation: 36583

Because there is not implicit conversion from int to Person. If you were to define an implicit conversion for Person, that should work:

http://msdn.microsoft.com/en-us/library/z5z9kes2(v=VS.100).aspx

Note in the example that a double value is implicitly convertable to a Digit type. You could define an implicit conversion for int to Person.

Upvotes: 4

triangulito
triangulito

Reputation: 202

You need to call the constructor to actually instance it. In your code you are basically saying that Person is of type int and this is not the case, the variable inside is.

You can do something like this to achieve what you want.

var v = new List<Person>() { new Person(1), new Person(2), new Person(3) };

Given that you have a constructor that accepts an int.

Like this one:

 public Person(int id)
 {
     Id = id;
 }

Upvotes: 0

Dustin Laine
Dustin Laine

Reputation: 38543

Because and integer is not the same as a Person object, and the Id is a property that needs to be assigned to.

var v = new List<Person>();
for (i = 1; i <= 3; i++) {
    var p = new Person() {
        Id = i;
    }
    v.Add(p);
}

Upvotes: 0

dlev
dlev

Reputation: 48596

Neither 1, nor 2, nor 3 are Person objects.

You could, though try:

var people = new List<Person>() { new Person() { Id = 1 }, new Person() { Id = 2 } , new Person() { Id = 3 } };

Upvotes: 0

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