Why can't I get a value of Current When I implemented IEnumerable?
.net, c#, ienumerable
Solution
This is because in order for the `Current` to become non-null, you need to call `MoveNext()` on the same object.
Your current code calls `MoveNext()` on a temporary object. Here is what's going on when you call
g.GetEnumerator().MoveNext()`;
Console.WriteLine(g.GetEnumerator().Current);
- A call of `GetEnumerator()` returns an object `x`
- A call `x.MoveNext()` is performed
- `x` becomes eligible for garbage collection, because it is not referenced from any variable in your program.
- When you call `g.GetEnumerator().Current`, a new object `y` is returned
- A call to `y.Current` is made, returning `null`, because there was no call of `MoveNext` on object `y`
When you add a variable `a`, however, you call `MoveNext` and `Current` on the same object, fixing the problem:
- A call of `GetEnumerator()` returns an object `x`, which is assigned to variable `a`
- A call `a.MoveNext()` is performed
- A call `a.Current` is performed
Problem
I did below work ``` class Program { class GenEnumerator<T> : IEnumerable { public T[] Values { get; set; } public IEnumerator GetEnumerator() { for (int i = 0; i < Values.Length; i++) yield return Values[i]; } } static void Main(string[] args) { GenEnumerator<string> g = new GenEnumerator<string>(); g.Values = new string[] { "a", "b", "c", "d", "e" }; g.GetEnumerator().MoveNext(); Console.WriteLine(g.GetEnumerator().Current); Console.ReadKey(); } } ``` `g.GetEnumerator().Current` is always null. but if I do this - `var a = g.GetEnumerator();` the Current proeperty gets a value and works fine Does it imply that I have to explicitly inherit the class from `IEnumerator` and implement its methods and property if I want to use `Current` without a `IEnumerator` type variable? Thanks, Roy