. NET-based iterators

The use of a Foreach loop is implemented with a IEnumerator interface, and IEnumerator implements an iterator that iterates over a collection ArrayList in foreach.

1. Call Arraylis.getenumberator () to return a ienumberator reference.
2. Invokes the MoveNext () method of the returned Enumberator interface.
3. If MoveNext () returns True, a reference to the object is obtained using the current property of the Ienumberator interface for the Foreach loop.
4. Repeat the first two steps, knowing that the MoveNext method returns false, at which time the loop stops.

Examples of implementations of iterators:

classProgram { Public Static voidMain (string[] args) {            foreach(stringStrinchSimpleList ())            {Console.WriteLine (str);        } console.readkey (); }         Public StaticIEnumerable SimpleList () {yield return "1"; yield return "2"; yield return "3"; }    }

This allows us to implement one of the simplest iterators. The result is:

Here is a more complicated example of using an iterator to implement the return prime:

 Public Static void Main (string[] args)        {            new Primes (2);             foreach (long in primesfrom2to1000)            {                Console.Write ("{0}", I);            }        }

 Public classPrimes {Private Longmin; Private LongMax;  PublicPrimes (): This(2, $)        { }         PublicPrimes (LongMinimumLongmaximum) {            if(Minimum <2) {min=2; }            Else{min=minimum; } Max=maximum; }         PublicSystem.Collections.IEnumerator GetEnumerator ()//return type is an iterator        {             for(Longpossibleprime = min; Possibleprime <= Max; possibleprime++)            {                BOOLIsPrime =true;  for(LongPossiblefactor =2; Possiblefactor <= (Long) Math.floor (Math.sqrt (possibleprime)); possiblefactor++)                {                    LongRemainderafterdivsion = possibleprime%Possiblefactor; if(Remainderafterdivsion = =0) {IsPrime=false;  Break; }                }                if(isprime) {yield returnPossibleprime;//for the prime number, the return                }            }        }    }

The result is:

There are two types of iterators returned: Ienumberable and IEnumerator.

• If you want to iterate over a class, you can use GetEnumerator (), whose return type is IEnumerator.
• If you want to iterate over a class member, such as a method, use IEnumerable.

. NET-based iterators