working pattern of yield return

Question

When i have a code block

static void Main()
{

  foreach (int i in YieldDemo.SupplyIntegers())
  {
    Console.WriteLine(\"{0} is consumed by foreach iteration\         


        

Answer 1

Simply put, iterator blocks (or methods with yield statements, if you may) are transformed by the compiler into a compiler-generated class. This class implements IEnumerator and the yield statement is transformed into a 'state' for that class.

For instance, this:

yield return 1;
yield return 2;
yield return 3;

might get transformed into something similar to:

switch (state)
{
    case 0: goto LABEL_A;
    case 1: goto LABEL_B;
    case 2: goto LABEL_C;
}
LABEL_A:
    return 1;
LABEL_B:
    return 2;
LABEL_C:
    return 3;

Iterator blocks are can be seen as abstracted state machines. This code will be invoked by IEnumerator's methods.