Unbox specific struct members

Question

Is it possible in the following example where i am boxing a struct named fraction, to then unbox a specific member of the struct for example the numerator?

using system;

struct fraction
    {
       public int numerator;
       public int denominator;
    }   

class Program
    {
        static void Main()
        {
            fraction f1;
            f1.denominator = 100;
            f1.numerator = 10;
            object obj = f1;

            // initializing f2.
            fraction f2 = new fraction();
            // Or can unbox the obj to the f2 like this.
            f2 = (fraction)obj;
            // But if i want to only unbox the numerator member of the struct fraction boxed inside the obj Something like this will not work
            f2.numerator = (fraction)obj.numerator;
        }
    }

Answer 1

It's not possible to unbox a member or property of a boxed object without unboxing the entire object.

The object is only accessible as a System.Object while in boxed state. Any operation on the original type requires unboxing.

Answer 2

You can't unbox an individual field without unboxing the entire object.

But maybe you just wanted to access the field, and are unsure of the correct syntax. After you unbox the original object, you can access the field by referencing the unboxed value:

fraction f2 = new fraction();
fraction originalFraction = (fraction)obj;   // unbox the object
int numerator = originalFraction.numerator;  // access the field on the unboxed fraction
f2.numerator = numerator;

You can shorten that to a single line, using object initialization, although ultimately it's doing the same thing as the above code:

fraction f2 = new fraction { numerator = ((fraction)obj).numerator };