c# yield usage

 

• 返回类型必须为 IEnumerable、IEnumerable<T>、IEnumerator 或 IEnumerator<T>。
  
  声明不能有任何 in、ref 或 out 参数。
  
  
  public class PowersOf2
  {
      static void Main()
      {
          // Display powers of 2 up to the exponent of 8:
          foreach (int i in Power(2, 8))
          {
              Console.Write("{0} ", i);
          }
      }
  
      public static System.Collections.Generic.IEnumerable<int> Power(int number, int exponent)
      {
          int result = 1;
  
          for (int i = 0; i < exponent; i++)
          {
              result = result * number;
              yield return result;
          }
      }
  
      // Output: 2 4 8 16 32 64 128 256
  }