Why can't I define both implicit and explicit operators?

Question

Why I cannot define both implicit and explicit operators like so?

    public class C     {         public static implicit operator string(C c)         {             return "implicit";         }          public static explicit operator string(C c)         {             return "explicit";         }     } 

You can do this hack though :)

    class Program     {         public class A         {          }          public class B         {             public static implicit operator A(B b)             {                 Console.WriteLine("implicit");                 return new A();             }         }          public class C : B         {             public static explicit operator A(C c)             {                 Console.WriteLine("explicit");                 return new A();             }         }          static void Main(string[] args)         {             C c = new C();              A a = c;             A b = (A) c;         }     } 

This prints:

implicit explicit 

Answer 1

Check this: Why can't coexist implicit and explicit operator of the same type in C#?

If you define an explicit operator, you will be able to do something like this:

Thing thing = (Thing)"value"; 

If you define an implicit operator, you can still do the above, but you can also take advantage of implicit conversion:

Thing thing = "value"; 

In short, explicit allows only explicit conversion, while implicit allows both explicit and implicit... hence the reason why you can only define one.

Answer 2

I don't know the technical limitation that prevents this, but I think they would have done this to prevent people from shooting their own feet off.

string imp = new C(); // = "implicit" string exp = (string)new C(); // = "explicit" 

That would drive me bonkers and makes no sense, C should only cast to a string 1 way, not 2 different ways.