按升序和降序对数组排序的C#

Question

public static bool IsArraySorted(int[] numbers)
{
    for (int i = 1; i < numbers.Length; i++)
    {
        if (numbers[i - 1] > numbers[i])
            return false;
    }

    return true;
}

有人能提供帮助，如何检查排序降序数组以及？干杯！

Answer 1

应该是这样的：

public static bool IsArraySorted(int[] numbers)
{
    bool? ascending = null;

    for (int i = 1; i < numbers.Length; i++)
    {
        if (numbers[i - 1] != numbers[i])
        {
            bool ascending2 = numbers[i - 1] < numbers[i];

            if (ascending == null)
            {
                ascending = ascending2;
            }
            else if (ascending.Value != ascending2)
            {
                return false;
            }
        }
    }

    return true;
}

注意使用升序变量保存数组的“方向”。第一次发现两个不同的元素时，它被初始化。

注意，如果你愿意，你甚至可以返回数组的“方向”：

public static bool IsArraySorted(int[] numbers, out bool isAscending)
{
    isAscending = true;
    bool? ascending = null;

if (ascending == null)
{
    ascending = ascending2;
    isAscending = ascending2;
}

public static bool IsSorted<TSource>(IEnumerable<TSource> source, out bool isAscending, Comparer<TSource> comparer = null)
{
    isAscending = true;

    if (comparer == null)
    {
        comparer = Comparer<TSource>.Default;
    }

    bool first = true;
    TSource previous = default(TSource);

    bool? ascending = null;

    foreach (TSource current in source)
    {
        if (!first)
        {
            int cmp = comparer.Compare(previous, current);

            if (cmp != 0)
            {
                bool ascending2 = cmp < 0;

                if (ascending == null)
                {
                    ascending = ascending2;
                    isAscending = ascending2;
                }
                else if (ascending.Value != ascending2)
                {
                    return false;
                }
            }
        }

        first = false;
        previous = current;
    }

    return true;
}