C# objects by Ref

Question

If one passes an object to a method using the \'Ref\' keyword then what is the difference with passing it without the ref keyword?

Because both yield the same result, th

Answer 1

I am limiting the discussion to reference types (everything that is a class, meaning I am not talking about structs or built-in value types). For a full and more detailed discussion you can see this link here.

If you pass reference types without the ref keyword you are passing the reference by value, meaning that a copy of your reference will be made. At this point you can modify the object the ref is pointing to, BUT if you swap in another object (assigning to the ref object you passed in some other object you create) when the function returns the original object that lives outside the function that you passed in is still pointing to the same old reference.

If you pass reference types using the ref keyword instead you can swap in the object you passed in with something else because the reference is not merely being copied - the variable itself is being passed in flesh and bones to the function to do whatever, and you can even make it point to some other address in memory (instantiating another object and assigning it to your ref parameter).

As you point out, in both cases you will be able to modify your object. Basically passing by reference in C# corresponds to passing a simple pointer in C++, while passing without the ref keyword corresponds to passing a constant pointer in C++ (you can make changes but can't make it point to smt else).