步驟 7：加入乘法和除法問題

發行項
05/17/2010

開始進行此程序之前，請先思考應該如何加入乘法和除法問題。思考初始步驟，其中牽涉到儲存值。

若要加入乘法和除法問題

將四個 int (Integer) 加入至表單。程式碼看起來應該如下所示。

Public Class Form1

    ' Create a Random object to generate random numbers.
    Dim randomizer As New Random

    ' These Integers will store the numbers in the addition problem.
    Dim addend1 As Integer
    Dim addend2 As Integer

    ' These Integers will store the numbers for the subtraction problem.
    Dim minuend As Integer
    Dim subtrahend As Integer

    ' These Integers will store the numbers for the multiplication problem.
    Dim multiplicand As Integer
    Dim multiplier As Integer

    ' These Integers will store the numbers for the division problem.
    Dim dividend As Integer
    Dim divisor As Integer

    ' This Integer will keep track of the time left.
    Dim 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;

如同先前一樣，修改 StartTheQuiz() 方法來填入隨機的乘法和除法問題。程式碼看起來應該如下所示。

''' <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，讓方法也檢查乘法和除法問題。程式碼看起來應該如下所示。

''' <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;
}

注意事項
因為使用鍵盤不容易輸入乘號 (×) 和除號 (÷)，所以 Visual C# 和 Visual Basic 使用星號 (*) 表示乘法，使用斜線符號 (/) 表示除法。

變更計時器的 Tick 事件處理常式的最後一部分，讓事件處理常式在時間結束時填入正確答案。程式碼看起來應該如下所示。

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;
}

儲存並執行您的程式。現在，必須回答四個問題才能完成測驗，如下列圖片所示。

含有四個問題的數學測驗

若要繼續或檢視

若要移到下一個教學課程步驟，請參閱步驟 8：嘗試其他功能。
若要回到上一個教學課程步驟，請參閱步驟 6：加入減法問題。

共用方式為

步驟 7：加入乘法和除法問題

若要加入乘法和除法問題

若要繼續或檢視

其他資源