C# – 从十进制数组中查找最接近的索引

decimal minDistance = 0; //0 is fine here it is never read,it is just to make the compiler happy.
int minIndex = -1;

for(int i = 0; i < array.Length; i++)
{
    var distance = Math.Abs(TargetNumber - array[i]);
    if(minIndex == -1 || distance < minDistance)
    {
        minDistance = distance;
        minIndex = i;

        //Optional,stop testing if we find a exact match.
        if(minDistance == 0)
            break;
    }
}

为了好玩,我制作了一个完全通用的版本,它要求你传入一个委托来计算距离因子,它还有一个可选参数来定义停止检查更多结果所需的“最小距离”.

using System;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        decimal[] array = new decimal[5]{80.23M,80.40M,80.80M,80.00M,20.45M};
        decimal TargetNumber = 70.40M;

        var result = FindClosestIndex(TargetNumber,array,(target,element) => Math.Abs(target - element)); //Optionally add in a "(distance) => distance == 0" at the end to enable early termination.

        Console.WriteLine(result);
    }

    public static int FindClosestIndex<T,U>(T target,IEnumerable<T> elements,Func<T,T,U> distanceCalculator,Func<U,bool> earlyTermination = null) where U : IComparable<U>
    {
        U minDistance = default(U);
        int minIndex = -1;

        using(var enumerator = elements.GetEnumerator())
        for(int i = 0; enumerator.MoveNext(); i++)
        {

            var distance = distanceCalculator(enumerator.Current,target);
            if(minIndex == -1 || minDistance.CompareTo(distance) > 0)
            {
                minDistance = distance;
                minIndex = i;
            }

            if(earlyTermination != null && earlyTermination(minDistance))
                break;
        }

        return minIndex;
    }
}

Runnable example