如何在 .NET 中修剪数组？

发布于 2024-08-11 07:04:23 字数 276 浏览 3 评论 0原文

假设我有一个数组

array<double>^ buffer = gcnew array<double>(100);

，我想要一个执行以下操作的函数：

void foo(array<double>^% buffer)
{
    Array::Resize(buffer, 10);
}

但是当您想要修剪数组时，它不会分配和/或移动 &buffer[0] 。

原文

Say I have an array

array<double>^ buffer = gcnew array<double>(100);

And I want a function that does something like:

void foo(array<double>^% buffer)
{
    Array::Resize(buffer, 10);
}

but that don't allocate and/or move &buffer[0] when you want to trim the array.

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转角预定愛 2024-08-18 07:04:23

.NET 数组一旦创建，大小就不可变。您无法修剪它；您必须重新分配和复制。所以 Array.Resize 已经完成了您需要的一切。如果您确实不想这样做，也许可以忽略最后的元素。

或者;使用List，它封装一个数组，并且确实有TrimExcess()。用 C# 术语来说：

    var list = new List<int>(100);
    // prints 0/100
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);
    list.Add(1);
    list.Add(2);
    list.Add(3);
    // prints 3/100
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);
    list.TrimExcess();
    // prints 3/3
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);

.NET arrays are immutable in size once created. You can't trim it; you must reallocate and copy. So Array.Resize already does everything you need. Perhaps just ignore the elements at the end if you really don't want to do this.

Or; use a List<T>, which encapsulates an array, and does have TrimExcess(). In C# terms:

    var list = new List<int>(100);
    // prints 0/100
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);
    list.Add(1);
    list.Add(2);
    list.Add(3);
    // prints 3/100
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);
    list.TrimExcess();
    // prints 3/3
    Console.WriteLine("{0} / {1}", list.Count, list.Capacity);

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