用WebService实现从指定数组中选择出任意个元素（续）

本文是对?用WebService实现从指定数组中选择出任意个元素?一文的补充，添加了重复约束检查功能：?

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using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;

namespace RandomWS
{
    /// <summary>
    /// Summary description for Service1
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [ToolboxItem(false)]
    // To allow this Web Service to be called from script,using ASP.NET AJAX,uncomment the following line. 
    // [System.Web.Script.Services.ScriptService]
    public class Service1 : System.Web.Services.WebService
    {

        [WebMethod]
        public string[] GenerateRandomColourArray(int numberOfRandomColours)
        {
            if (numberOfRandomColours > 13)
                return null;
            string[] colourPalette = { "Red","Blue","White","Black","Green","Yellow","Purple","Pink","Brown","Grey","Orange","Cyan","Magenta" };
            Random random = new Random();
            string[] arr = new string[numberOfRandomColours];
            bool[] br = new bool[13];//初始值都是false
            for (int j = 0; j < numberOfRandomColours; j++)
            {
               int i = 0;
               bool b = false;
               while (b == false)
               {
                   i = random.Next(0,13);
                   if (br[i] == false)//在br数组中查找br[i]的值是否为false,如果为false,表示i值是第一次得到，如果是true,表示i值已经存在了，就不跳出while循环，继续执行while。
                       b = true;
               }
               br[i] = true;//初次得到i的值时，将br[i]赋值为true。
               arr[j] = colourPalette[i];//取出colourPalette数组中的颜色，放在arr数组中。
            }
            return arr;//返回存放随机找到的颜色的数组arr。
        }
        
    }
}