枚举器对象与可枚举类型

class ColorEnumerator : IEnumerator   //实现枚举器接口：Current，MoveNext，Reset共3种方法
    {
        string[] _colors;
        int _position = -1;
        public ColorEnumerator(string[] theColors)
        {
            _colors =new string[theColors.Length];
            for (int i = 0; i < theColors.Length; i++)
            {
                _colors[i]=theColors[i];
            }
        }

        public object Current
        {
            get
            {
                if (_position==-1)
                {
                    throw new InvalidOperationException();
                }
                if (_position>=_colors.Length)
                {
                    throw new InvalidOperationException();
                }
                return _colors[_position];
            }
        }
        public bool MoveNext()
        {
            if (_position < _colors.Length - 1)
            {
                _position++;
                return true;
            }
            else
            {
                return false;
            }
        }
        public void Reset()
        {
            _position = -1;
        }
    }
    class Spectrum : IEnumerable//实现可枚举类型接口，返回枚举器
    {
        string[] Colors = { "violet","blue","cyan","green","yellow","orange","red"};
        public IEnumerator GetEnumerator()
        {
            return new ColorEnumerator(Colors);
        }    
   }
    class Program
    {
        static void Main()
        {
            Spectrum spectrum = new Spectrum();
            foreach (string color in spectrum)
            {
                Console.WriteLine(color);
            }
            Console.Read();
        }
    }