What's the difference between an object initializer and a constructor?

Question

What are the differences between the two and when would you use an \"object initializer\" over a \"constructor\" and vice-versa? I\'m working with C#, if that matters. Als

Answer 1

A constructor is a method (possibly) accepting parameters and returning a new instance of a class. It may contain initialization logic. Below you can see an example of a constructor.

public class Foo
{
    private SomeClass s;
    public Foo(string s)
    {
       s = new SomeClass(s);
    }
}

Now consider the following example:

public class Foo
{
    public SomeClass s { get; set; }
    public Foo() {}
}

You could achieve the same result as in the first example using an object initializer, assuming that you can access SomeClass, with the following code:

new Foo() { s = new SomeClass(someString) }

As you can see, an object initializer allows you to specify values for public fields and public (settable) properties at the same time construction is performed, and that's especially useful when the constructor doesn't supply any overload initializing certain fields. Please mind, however that object initializers are just syntactic sugar and that after compilation won't really differ from a sequence of assignments.