随机数生成

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

namespace Exam.BLL
{
    /**//// <summary>
    /// 帮助生成随机数类
    /// </summary>
    class RandomNumberHelper
    {
        /**//// <summary>
        /// 从指定列表中随机取出指定个数整数以新列表返回
        /// </summary>
        /// <param name="sourceList">原列表</param>
        /// <param name="selectCount">要选取个数</param>
        /// <returns>新列表</returns>
        public static IList<int> RandomSelect(IList<int> sourceList,int selectCount)
        {
            if (selectCount > sourceList.Count)
                throw new ArgumentOutOfRangeException("selectCount必需大于sourceList.Count");
            IList<int> resultList = new List<int>();
            for (int i = 0; i < selectCount; i++)
            {
                int nextIndex = GetRandomNumber(1, sourceList.Count);
                int nextNumber = sourceList[nextIndex-1];
                sourceList.RemoveAt(nextIndex-1);
                resultList.Add(nextNumber);     
            }
            return resultList;
        }
        /**//// <summary>
        /// 生成一个整数大于等于最小值，小于等于最大值
        /// </summary>
        /// <param name="minValue">最小值</param>
        /// <param name="maxValue">最大值</param>
        /// <returns>整数，大于等于最小值，小于等于最大值</returns>
        public static int GetRandomNumber(int minValue, int maxValue)
        {
            return random.Next(minValue, maxValue+1);
        }
        private static Random random = new Random();
    }
}