static void Main(string[] args)
{
while (true)
{
int a;
Random r = new Random();
a = r.Next(0,24);
Console.WriteLine(a);
if (a >= 0 && a < 6)
{
Console.WriteLine("凌晨"+a+"点");
}
else if (a >= 6 && a < 12)
{
Console.WriteLine("上午" + a + "点");
}
else if (a >= 12 && a < 18)
{
Console.WriteLine("下午" + (a-12) + "点");
}
else if (a >= 18 && a <= 24)
{
Console.WriteLine("晚上" + (a - 12) + "点");
}
else
{
Console.WriteLine("对不起，出错了");
}
}
原文：http://www.cnblogs.com/w-wz/p/4439004.html