Question

In C#, why can’t I pass an unassigned object variable in an out parameter and then assign it?

If I try to do this, there is a compiler error: “Local variable <xyz> cannot be declared in this scope because it would give a different meaning to <xyz>…”

eg.

void MyMethod(int x, out MyObject mo) {  **MyObject** mo = new MyObject(); }
// in some other scope:
MyObject mo;
MyMethod(1, out mo);

EDIT: I can see my mistake now. I have changed the above code to what mine was. The MyObject in asterisks should not be there.

Answer 1

The code you posted original was incorrect, but now we see that the problem is actually here:

void MyMethod(int x, out MyObject mo)
{
    MyObject mo = new MyObject();
    // should be:
    // mo = new MyObject();
}

You’re creating a new local variable mo which “hides” the parameter mo.

Glad we got there in the end 🙂