C#数据结构中常用的算法1：二分法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DataOperateCsharp
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] array=new int[18];
            for (int i = 0; i < array.Length; i++)
            {
                array[i] = i+3;
            }
            int numToFind = 7;//查找7在数组中的位置
            int numIndexInArray=HalfFind(array, numToFind);
            Console.WriteLine(numIndexInArray.ToString());
            Console.Read();
            
        }
        /// <summary>
        /// 二分查找法
        /// </summary>
        /// <param name="arr">数组</param>
        /// <param name="value">要查找的数值</param>
        /// <returns></returns>
        static int HalfFind(int[] arr,int value)
        {
            int low = 0;
            int high = arr.Length;
            while (low<=high)
            {
                int mid = (high + low) / 2;
                if (arr[mid] == value)
                    return mid;
                else if (arr[mid] > value)
                {
                    high = mid - 1;
                }
                else
                {
                    low = mid + 1;
                }                
            }
            return 0;
        }
    }
}