using System;

namespace Span复习

{

    class Program

    {

        static void Main(string[] args)

        {

            //Console.WriteLine("Hello World!");

            //IntroSpans();

            //var span1 = IntroSpans();

            //CreatSlices(span1);

            int[] int1 = {,,,,,,,,,,};

            int[] int2 = {,,,,,,};

            var span1 = new Span<int>(int1);

            var span2 = new Span<int>(int2);

            ChangeValues(span1,span2);

        }

        //使用Span<T>，可以直接访问数组元素。数组的元素没有复制，但是它们可以直接使用，这比复制要快。

        private static Span<int> IntroSpans()

        {

            int[] arr1 = new int[] {,,,,,};

            var span1 = new Span<int>(arr1);

            span1[] = ;

            System.Console.WriteLine($"arr1[1] is changed via span[1]: {arr1[1]}");

            System.Console.WriteLine($"span1[1]: {span1[1]}");

            return span1;

        }

        //创建切片

        private static void CreatSlices(Span<int> span1)

        {

            System.Console.WriteLine(nameof(CreatSlices));

            int[] arr2 = {,,,,,,};

            //var span2 = new Span<int>(arr2);

            var span3 = new Span<int>(arr2,start:,length:);

            var span4 = span1.Slice(start:,length:);

            DisplaySpan("Content of span3:",span3);

            DisplaySpan("Content of span4:" ,span4);

            System.Console.WriteLine();

        }

        //DisplaySpan()用于显示Span的内容

        private static void DisplaySpan(string title,ReadOnlySpan<int> span)

        {

            System.Console.WriteLine(title);

            for(int i = ;i<span.Length;i++)

            {

                System.Console.Write($"{span[i]} ");

            }

            System.Console.WriteLine();

        }

        //使用Span改变值

        private static void ChangeValues(Span<int> span1,Span<int> span2)

        {

            System.Console.WriteLine(nameof(ChangeValues));

            var span4 = span1.Slice(start:);

            span4.Clear();//清除了span1从第5位开始后面的数，并用数0填充

            DisplaySpan("content of span1",span1);

            var span5 = span2.Slice(start:,length:);

            span5.Fill();//span2从第4位开始的三位，用数42来填充

            DisplaySpan("content of span2",span2);

            span5.CopyTo(span1);

            DisplaySpan("content of span1",span1);

            if(!span1.TryCopyTo(span4))

            {

                System.Console.WriteLine("Couldn't copy span1 to span4 because span4 is to small ");

                System.Console.WriteLine($"length of span1: {span1.Length},length of span4: {span4.Length} ");

            }

            System.Console.WriteLine();

        }

    }

}

ChangeValues

content of span1

content of span2

content of span1

Couldn't copy span1 to span4 because span4 is to small

length of span1: ,length of span4: