yield return区别

internal class Program
{
    static List<int> GetInitialData()
    {
        return new List<int>() { 1, 2, 3, 4 };
    }

    static IEnumerable<int> FilerWithoutYield()
    {
        List<int> result = new List<int>();
        foreach (var item in GetInitialData())
        {
            if (item > 2)
            {
                result.Add(item);
            }
        }
        return result;
    }

    static IEnumerable<int> FileWithYield()
    {
        foreach (var item in GetInitialData())
        {
            if (item > 2)
            {
                yield return item;
            }
        }
        yield break;
        Console.WriteLine("这里的代码不执行");
    }

    static void Main(string[] args)
    {
        foreach (var item in FilerWithoutYield())
        {
            Console.WriteLine(item);
        }

        foreach (var item in FileWithYield())
        {
            Console.WriteLine(item);
        }

        Console.ReadKey();
    }
}