IEnumerable接口與IEnumerator

1.如果要迭代一個類，可以使用方法GetEnumerator（），使其返回類型是IEnumerator
2.如果要迭代一個類成員，例如一個方法，則使用IEnumerable

 

//使用IEnumerable using System; using System.Collections; namespace MyEx { public class IEnumerableDemo { public static IEnumerable SimpleList() { yield return "string 1"; yield return "string 2"; yield return "string 3"; yield return "string 4"; } public static void Main(string[] args) { Console.WriteLine("use IEnumerable.notice IEnumerable uses in method"); foreach (string item in SimpleList()) { Console.WriteLine(item); } } } } 

 

//使用GetEnumerator using System; using System.Collections; namespace MyEx { public class Primes { private long _min; private long _max; private Primes() { } public Primes(long min, long max) { if (min < 2) { this._min = 2; } else if (min >= max&&max >= 2) { this._min = max; this._max = min; } else if (min >= max && max < 2) { this._min = 2; this._max = min; } else { this._min = min; this._max = max; } } public IEnumerator GetEnumerator() { for (long possiblePrime = this._min; possiblePrime <= this._max;possiblePrime++) { bool isPrime = true; for (long possibleFactor = 2; possibleFactor <= (long)Math.Floor(Math.Sqrt(possiblePrime)); possibleFactor++) { if (possiblePrime % possibleFactor == 0) { isPrime = false; break; } } if (isPrime) { yield return possiblePrime; } } } } public class GetEnumerableDemo { public static void Main(string[] args) { long min = Convert.ToInt32(args[0]); long max = Convert.ToInt32(args[1]); Primes primes = new Primes(min, max); Console.WriteLine("begin to print prime!"); foreach (long i in primes) { Console.WriteLine(i); } Console.WriteLine("printing prime is over!"); } } }