how create a generic method that can initialize value variable to 0 or ref variable to new (not null)

I have something like this

V Func<V>()
{
  // do stuff
  V res = default(V);
 // more stuff
  return res;
}

The problem is that I want res to be either 0 or a new instance of V

I tried creating 2 methods

Func<V> where T: new()
Func<V> where T: struct

but surprisingly this is not allowed

My workaround is to have 2 functions

Fu开发者_如何学CncNew<V> where T: new()
...
res = new V();
....

and

FuncDefault<V> where T: struct
...
res = default(V)
...

EDIT: Summarize answers

new(T) will new up a ref or value type; I did not realize that

You can use the new() constraint:

private V Func<V>() where V : new()
{
  // do stuff
  V res = new V();
 // more stuff
  return res;
}

Value types will be initialized to all-zeros, and any reference types will be initialized using their no-args default constructor.

If the reference type doesn't have a no-args constructor it can't be used with this method, and you'll have to use other ways (there are plenty of solutions to this problem elsewhere on SO, eg Passing arguments to C# generic new() of templated type)

So you want the result object to be integer zero, or a new instance of your generic type? That's not possible because the generic type parameter would only be valid for the integer type unless you specify object as the return type.

public object Func<T>()
     where T: new()
{
    if(something)
       return 0;

    return new T();
}

If you're trying to make a default initializer, you just need to new up the type. This should work for both integer and reference types.

public T Func<T>()
{
    return Activator.CreateInstance<T>();
}