为什么最后iNum的值会等于iResult的值啊，请高手指点啊

Random ran = new Random(); int iNum1 = ran.Next(10); int iNum2 = ran.Next(10); int iopen = ran.Next(4); string[] arrOper = { "+", "-", "*", "/" }; Console.Write(iNum1 + " " + arrOper[iopen] + " " + iNum2 + " = "); int iResult = int.Parse(Console.ReadLine()); switch(iopen) { case 0: iNum1 = iNum1 + iNum2; break; case 1: iNum1 = iNum1 - iNum2; break; case 2: iNum1 = iNum1 * iNum2; break; case 3: iNum1 = iNum1 / iNum2; break; } Console.WriteLine(iNum1 == iResult ? "答案正确" : "答案错误，正确答案为" + iNum1 + " ");
这样懂了么