步骤 7:添加乘法和除法问题
开始此过程之前,请先考虑应如何添加乘法和除法问题。考虑与存储值相关的初始步骤。
添加乘法和除法问题
向窗体添加四个 int (Integer) 变量。代码应如下所示。
Public Class Form1 ' Create a Random object to generate random numbers. Private randomizer As New Random ' These Integers will store the numbers in the addition problem. Private addend1 As Integer Private addend2 As Integer ' These Integers will store the numbers for the subtraction problem. Private minuend As Integer Private subtrahend As Integer ' These Integers will store the numbers for the multiplication problem. Private multiplicand As Integer Private multiplier As Integer ' These Integers will store the numbers for the division problem. Private dividend As Integer Private divisor As Integer ' This Integer will keep track of the time left. Private timeLeft As Integer
public partial class Form1 : Form { // Create a Random object to generate random numbers. Random randomizer = new Random(); // These ints will store the numbers for the addition problem. int addend1; int addend2; // These ints will store the numbers for the subtraction problem. int minuend; int subtrahend; // These ints will store the numbers for the multiplication problem. int multiplicand; int multiplier; // These ints will store the numbers for the division problem. int dividend; int divisor; // This int will keep track of the time left. int timeLeft;
与前面一样,修改 StartTheQuiz() 方法以填入随机的乘法和除法问题。代码应如下所示。
''' <summary> ''' Start the quiz by filling in all of the problems ''' and starting the timer. ''' </summary> ''' <remarks></remarks> Public Sub StartTheQuiz() ' Fill in the addition problem. addend1 = randomizer.Next(51) addend2 = randomizer.Next(51) plusLeftLabel.Text = addend1.ToString() plusRightLabel.Text = addend2.ToString() sum.Value = 0 ' Fill in the subtraction problem. minuend = randomizer.Next(1, 101) subtrahend = randomizer.Next(1, minuend) minusLeftLabel.Text = minuend.ToString() minusRightLabel.Text = subtrahend.ToString() difference.Value = 0 ' Fill in the multiplication problem. multiplicand = randomizer.Next(2, 11) multiplier = randomizer.Next(2, 11) timesLeftLabel.Text = multiplicand.ToString() timesRightLabel.Text = multiplier.ToString() product.Value = 0 ' Fill in the division problem. divisor = randomizer.Next(2, 11) Dim temporaryQuotient As Integer = randomizer.Next(2, 11) dividend = divisor * temporaryQuotient dividedLeftLabel.Text = dividend.ToString() dividedRightLabel.Text = divisor.ToString() quotient.Value = 0 ' Start the timer. timeLeft = 30 timeLabel.Text = "30 seconds" Timer1.Start() End Sub
/// <summary> /// Start the quiz by filling in all of the problems /// and starting the timer. /// </summary> public void StartTheQuiz() { // Fill in the addition problem. addend1 = randomizer.Next(51); addend2 = randomizer.Next(51); plusLeftLabel.Text = addend1.ToString(); plusRightLabel.Text = addend2.ToString(); sum.Value = 0; // Fill in the subtraction problem. minuend = randomizer.Next(1, 101); subtrahend = randomizer.Next(1, minuend); minusLeftLabel.Text = minuend.ToString(); minusRightLabel.Text = subtrahend.ToString(); difference.Value = 0; // Fill in the multiplication problem. multiplicand = randomizer.Next(2, 11); multiplier = randomizer.Next(2, 11); timesLeftLabel.Text = multiplicand.ToString(); timesRightLabel.Text = multiplier.ToString(); product.Value = 0; // Fill in the division problem. divisor = randomizer.Next(2, 11); int temporaryQuotient = randomizer.Next(2, 11); dividend = divisor * temporaryQuotient; dividedLeftLabel.Text = dividend.ToString(); dividedRightLabel.Text = divisor.ToString(); quotient.Value = 0; // Start the timer. timeLeft = 30; timeLabel.Text = "30 seconds"; timer1.Start(); }
修改 CheckTheAnswer() 方法,使此方法还检查乘法和除法问题。代码应如下所示。
''' <summary> ''' Check the answer to see if the user got everything right. ''' </summary> ''' <returns>True if the answer's correct, false otherwise.</returns> ''' <remarks></remarks> Public Function CheckTheAnswer() As Boolean If addend1 + addend2 = sum.Value AndAlso minuend - subtrahend = difference.Value AndAlso multiplicand * multiplier = product.Value AndAlso dividend / divisor = quotient.Value Then Return True Else Return False End If End Function
/// <summary> /// Check the answer to see if the user got everything right. /// </summary> /// <returns>True if the answer's correct, false otherwise.</returns> private bool CheckTheAnswer() { if ((addend1 + addend2 == sum.Value) && (minuend - subtrahend == difference.Value) && (multiplicand * multiplier == product.Value) && (dividend / divisor == quotient.Value)) return true; else return false; }
说明 由于没有使用键盘输入乘号 (×) 和除号 (÷) 的简单方法,因此 Visual C# 和 Visual Basic 使用星号 (*) 代替乘号,并使用左斜线 (/) 代替除号。
更改计时器的 Tick 事件处理程序的最后部分,使其在时间用完时填入正确答案。代码应如下所示。
Else ' If the user ran out of time, stop the timer, show ' a MessageBox, and fill in the answers. Timer1.Stop() timeLabel.Text = "Time's up!" MessageBox.Show("You didn't finish in time.", "Sorry") sum.Value = addend1 + addend2 difference.Value = minuend - subtrahend product.Value = multiplicand * multiplier quotient.Value = dividend / divisor startButton.Enabled = True End If
else { // If the user ran out of time, stop the timer, show // a MessageBox, and fill in the answers. timer1.Stop(); timeLabel.Text = "Time's up!"; MessageBox.Show("You didn't finish in time.", "Sorry"); sum.Value = addend1 + addend2; difference.Value = minuend - subtrahend; product.Value = multiplicand * multiplier; quotient.Value = dividend / divisor; startButton.Enabled = true; }
保存并运行程序。此时,必须回答四个问题才能完成测验,如下图所示。
包含四个问题的数学测验
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若要转到下一个教程步骤,请参见步骤 8:尝试其他功能。
若要返回上一个教程步骤,请参见步骤 6:添加减法问题。