Question

Why does’t this code output the value of 50?

class Program
{
    static void Main(string[] args)
    {
        var myClass = new TestConstructor() { MyInt = 50 };
    }
}

class TestConstructor
{
    public int MyInt { get; set; }

    public TestConstructor()
    {
        Console.WriteLine(this.MyInt);
        Console.Read();
    }
}

Answer 1

This code:

 var myClass = new TestConstructor() { MyInt = 50 };

is effectively transformed into:

var tmp = new TestConstructor();
tmp.MyInt = 50;
var myClass = tmp;

How would you expect the property to be set before the constructor was executed?

(The use of a temporary variable here isn’t important in this case, but it can be in other cases:

var myClass = new TestConstructor { MyInt = 50 };
myClass = new TestConstructor { MyInt = myClass.MyInt + 2 };

In the second line, it’s important that myClass.MyInt still refers to the first object, not the newly-created one.)