習題練習

A1.印出等第
        Dim a As Single
        Dim s As String
        a = InputBox("輸入a=", "成績", 0)
        Select Case a
            Case Is >= 90
                s = "優"
            Case Is >= 80
                s = "甲"
            Case Is >= 70
                s = "乙"
            Case Is >= 60
                s = "丙"
            Case Else
                s = "丁"
        End Select
        Me.TextBox1.Text = s

A2.求 2^2 + 4^2 +..... + 100^2 結果

        Dim sum = 0
        For i = 2 To 100 Step 2
            sum += i ^ 2
        Next
        Me.TextBox2.Text = sum


A3.一元二次方程式
        Dim a, b, c As Integer
        Dim ans = ""
        a = InputBox("輸入a=", "求解", 0)
        b = InputBox("輸入b=", "求解", 0)
        c = InputBox("輸入c=", "求解", 0)
        Dim d As Single = (b ^ 2 - 4 * a * c)
        If d > 0 Then
            ans &= "有相異實根" & "X = " & (-1 * b + d ^ 0.5) / (2 * a) & " , " & (-1 * b - d ^ 0.5) / (2 * a)
        ElseIf d = 0 Then
            ans = "有重根 , " & "x = " & (-1 * b) / (2 * a)
        Else
            ans = "有相異虛根 , " & "此方程式不存在"
        End If
        Me.TextBox3.Text = ans

A5. 三角形

        Dim a, b, c As Single
        Dim ans As String = ""
        a = InputBox("a =", "判斷是否能構成三角形?", 0)
        b = InputBox("b =", "判斷是否能構成三角形?", 0)
        c = InputBox("c =", "判斷是否能構成三角形?", 0)
        If a + b > c And a + c > b And b + c > a Then
            Dim s As Single = (a + b + c) / 2
            ans = "三角形面積 = " & (s * (s - a) * (s - b) * (s - c)) ^ 0.5
        Else
            ans = "非三角形"
        End If
        Me.TextBox5.Text = ans