VB编程练习题
1、* 编写程序：输入一元二次方程的系数a,b,c的值，求解一元二次方程的根。
Private Sub Command1_Click()
Dim a#, b#, c#
a = Val(InputBox("参数a="))   
b = Val(InputBox("参数b="))               
c = Val(InputBox("参数c="))               
Call root(a, b, c)
End Sub
Private Sub root(x#, y#, z#)
Dim t#, x1#, X2#
t = y * y - 4 * x * z
If t > 0 Then
x1 = (-y + Sqr(t)) / (2 * x)
X2 = (-y - Sqr(t)) / (2 * x)
Print "实根"; "x1="; x1, "x2="; X2               
Else
x1 = -y / (2 * x): X2 = Sqr(Abs(t)) / (2 * x)
Print "虚根", "x1=" & x1 & "+" & X2 & "i"     
End If
End Sub
2* 编写程序：* 计算并输出下面级数前n项（n=50）的部分和。1*2+2*3+3*4+4*5+……+n*(n+1)+…
Private Sub Command1_Click()
Dim i As Integer, n As Integer, sum As long
n = Val(Text1.Text)
For i = 1 To n
sum = sum + i * (i + 1)
Next  i                               
Print sum
End Sub
3  * 编写程序：设计一个程序，随机产生一个三位正整数，然后逆序输出，产生的数与逆序
数同时显示。
Private Sub Command1_Click()
Dim y
Randomize
X = Int(Rnd * 900 + 100)
Print X
y= strreverse(x)
print y
End Sub
4* 编写程序：* 要求能够产生一个[10，100]内（包括10和100）的一个随机数，然后判断其是否是素数。 * 如果是，在窗体上输出"yes"，否则，输出"no"。
Private Sub Command1_Click()
a = Int(10 + 91 * Rnd)
For i = 2 To Int(Sqr(a))
If (a Mod i) = 0 Then
Print a & ":" & "no"
Exit Sub
End If
Next i
Print a & ":" & "yes"
End Sub
5、*  编写程序：使用级数求π的值。根据下式，计算圆周率π的近似值，当计算到绝对值小于0.0001的通项时，认为满足精度要求，停止计算。
用到的公式为π/4=1-1/3+1/5-1/7+...
Private Sub Command1_Click()
Dim s!, n!, t!, pi!
t = 1: pi = 0: n = 1: s = 1
While Abs(t) >= 0.0001
pi = pi + t
n = n + 2
s = -s
t = s / n
Wend
pi = pi * 4
Print pi
End sub
6、* 编写程序：* 使用双重循环，在窗体上输出“九九乘法表”的上三角。
Private Sub Command2_Click()
Dim I As Integer, J As Integer
For I = 1 To 9
For J = I To 9
Print Format(I * J, I & "x" & J & "=@@ ");
Next
Print
Print Space(7 * I);
Next
End Sub
7* 编写程序：利用文本框输入一个年份，编程判定该年份是否是闰年。判定条件是：能被400整除，或者能被4整除但不能被100整除的年份是闰年。在文本框中输入年份，使用print输出是否为闰年。
Private Sub Command1_Click()
Dim i As Integer, s As Integer
s = Int(Text1.Text)
If s Mod 400 = 0 Or (s Mod 4 = 0 And s Mod 100 <> 0) Then
Print "闰年"
Else
Print "不是闰年" vb编程基础知识题库
End If
End Sub
8、* 编写程序：百钱买百鸡。公元前5世纪，我国数学家张丘建在《算经》中提出“百鸡问题”：鸡翁一值钱五，鸡母一值钱三，鸡雏三值钱一。百钱买百鸡，问鸡翁、鸡母、鸡雏各几何？
Private Sub Command1_Click()
For x = 0 To 30
For y = 0 To 33
If 5 * x + 3 * y + (100 - x - y) / 3 = 100 Then
Print  x,y,100 - x - y
End  If
Next y
Next x
注：X代表公鸡，Y代表母鸡
146第二题
Private Sub Form_Load()
    Command1.MousePointer = vbCrosshair
    Text1.MousePointer = vbHourglass
    Picture1.MousePointer = vbCustom
    End Sub
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = 2 Then MsgBox "现在鼠标光标位于图片框中"
End Sub
Private Sub text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = 2 Then MsgBox "现在鼠标光标位于文本框中"
End Sub
Private Sub command1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = 2 Then MsgBox "现在鼠标光标位于命令按钮中"
End Sub
11. 编写程序，用键盘完成，在从键盘上输入到Text1中的一组字符串中到其中的数Private Sub Command1_Click()
    Dim str As String， tmp As String，i As Integer，a(1 To 100) As Variant
    Dim n As Integer
    str = Text1.Text
    n = 0
    For i = 1 To Len(str)
        tmp = Mid(str, i, 1)
        If tmp > "0" And tmp < "9" Then
            a(i) = tmp
            n = n + 1
        End If
    Next i
  If n = 1 Then
ElseIf n = 0 Then
    MsgBox "没有数字！！！"
Else
    For i = 1 To Len(str) - 1
        For j = i + 1 To Len(str)
            If a(i) < a(j) Then
                tmp = a(i)
                a(i) = a(j)
                a(j) = tmp
            Else
            End If
        Next j
    Next i
End If
For i = 1 To Len(str)
  Text2.Text = Text2.Text & a(i)
Next i
End Sub

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