asp.net 无重复随机数代码

代码如下:
/// <summary>
/// 产生无重复随机数
/// </summary>
/// <param name="num">个数</param>
/// <param name="minValue">最小数</param>
/// <param name="maxValue">最大数</param>
/// <returns>数组</returns>
public int[] getNum(int num, int minValue, int maxValue)
{
Random ra = new Random(unchecked((int)DateTime.Now.Ticks));
int[] arrNum = new int[num];//注意:数组中各元素的初始值是0,当0在取值范围内时要另处理
int tmp = 0;
for (int i = 0; i < num; i++)
{
tmp = getRandomNum(tmp, minValue, maxValue, ra);//取出值赋到数组中

if (Array.IndexOf(arrNum, tmp) < 0)//判断是否存在,不存在的话元素tmp的索引应为-1
{
arrNum[i] = tmp;
}
else
{
i = i - 1;
}
}
return arrNum;
}
public int getRandomNum(int tmp, int minValue, int maxValue, Random ra)
{
tmp = ra.Next(minValue, maxValue);
return tmp;
}