C#数组切片方法

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namespace CSharpDemo
{
    class CSharpDemo
    {
        public static void Main(string[] args)
        {
            Slice sp = new Slice();
            sp.Test();
            Console.WriteLine();
        }
    }

    public class Slice
    {
        public void Test()
        {
            var array = new int[] { 0, 1, 2, 3, 4, 6, 7, 8, 9 };
            
            //C＃8.0  .Net Core 3.0
            var sub1 = array[0..4];
            PrintArray("array[0..4]", sub1);

            var sub2 = array[2..^2];
            PrintArray("array[2..^2]", sub2);

            var sub3 = array[2..^0];
            PrintArray("array[2..^0]", sub3);

            //ArraySegment不会复制数组
            var arraySegment = new ArraySegment<int>(array, 1, 7);
            PrintArray("ArraySegment<int>(array, 1, 7)", arraySegment);
            
            //ArraySegment.Slice
            var trainingData = arraySegment.Slice(0, 3);
            var testingData = arraySegment.Slice(3, 2);
            PrintArray("arraySegment.Slice(0, 3)", trainingData);
            PrintArray("arraySegment.Slice(3, 2)", testingData);
            
            //Linq
            var bar = array.Take(4);
            PrintArray("array.Take(4)", bar);

            var subset = array.Skip(2).Take(4);
            PrintArray("array.Skip(2).Take(4)", subset);

            //Array.Copy
            int[] dest = new int[4];
            Array.Copy(array, 0, dest, 0, 4);
            PrintArray("Array.Copy(array, 0, dest, 0, 4)", dest);
            
            //Utilizing ReadOnlySpan<T> or Span<T> to Slice Arrays
            var span1 = new ReadOnlySpan<int>(array, 0, 3);
            var span2 = new ReadOnlySpan<int>(array, 3, 2);
            
            Console.Write("ReadOnlySpan span1:");
            foreach (var record in span1)
                Console.Write(record);
            Console.WriteLine();
            Console.Write("ReadOnlySpan span2:");
            foreach (var record in span2)
                Console.Write(record);
        }

        public void PrintArray(string type, IEnumerable<int> ieArray)
        {
            Console.WriteLine($"{type} -> {string.Join("|", ieArray)}");
        }
    }
}

输出结果

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array[0..4] -> 0|1|2|3
array[2..^2] -> 2|3|4|6|7
array[2..^0] -> 2|3|4|6|7|8|9
ArraySegment<int>(array, 1, 7) -> 1|2|3|4|6|7|8
arraySegment.Slice(0, 3) -> 1|2|3
arraySegment.Slice(3, 2) -> 4|6
array.Take(4) -> 0|1|2|3
array.Skip(2).Take(4) -> 2|3|4|6
Array.Copy(array, 0, dest, 0, 4) -> 0|1|2|3
ReadOnlySpan span1:012
ReadOnlySpan span2:34

参考

https://code-maze.com/csharp-array-slicing/