C#使用stackalloc分配堆栈内存和非托管类型详解

int length = 3;
Span<int> numbers = stackalloc int[length];
for (var i = 0; i < length; i++)
{
    numbers[i] = i;
}

int length = 1000;
Span<byte> buffer = length <= 1024 ? stackalloc byte[length] : new byte[length];

Span<int> numbers = stackalloc[] { 1, 2, 3, 4, 5, 6 };
var ind = numbers.IndexOfAny(stackalloc[] { 2, 4, 6, 8 });
Console.WriteLine(ind);  // output: 1

unsafe
{
    int length = 3;
    int* numbers = stackalloc int[length];
    for (var i = 0; i < length; i++)
    {
        numbers[i] = i;
    }
}

const int MaxStackLimit = 1024;
Span<byte> buffer = inputLength <= MaxStackLimit ? stackalloc byte[MaxStackLimit] : new byte[inputLength];

Span<int> first = stackalloc int[3] { 1, 2, 3 };
Span<int> second = stackalloc int[] { 1, 2, 3 };
ReadOnlySpan<int> third = stackalloc[] { 1, 2, 3 };

using System;
public struct Coords<T>
{
    public T X;
    public T Y;
}
public class UnmanagedTypes
{
    public static void Main()
    {
        DisplaySize<Coords<int>>();
        DisplaySize<Coords<double>>();
    }
    private unsafe static void DisplaySize<T>() where T : unmanaged
    {
        Console.WriteLine($"{typeof(T)} is unmanaged and its size is {sizeof(T)} bytes");
    }
}
// Output:
// Coords`1[System.Int32] is unmanaged and its size is 8 bytes
// Coords`1[System.Double] is unmanaged and its size is 16 bytes

public struct Coords<T> where T : unmanaged
{
    public T X;
    public T Y;
}