16．界面如下图所示。编写适当的事件过程，程序运行后在三个文本框中分别输入三角形的边长值，单击“判断并计算”按钮，判断它们是否能组成三角形，若能组成三角形在Text4中显示三角形的面积 ，否则在Text4中显示“FALSE”。
Private Sub Command1_Click()
a = Val(Text1):b = Val(Text2):c = Val(Text3)
If a + b < c Or a + c < b Or b + c < a Or Abs(a - b) > c Or Abs(a - c) > b Or Abs(b - c) > a Then = \ Else
h = (a + b + c) / 2
s = Sqr(h * (h - a) * (h - b) * (h - c)) = Format(s, \End If End Sub
17．设计一个程序运行界面如下图所示，将输入的三个不同数，按从小到大的顺序排列。
Private Sub Command1_Click()
a = Val(Text1):b = Val(Text2):c = Val(Text3) If a < b Then t = a: a = b: b = t If a < c Then t = a: a = c: c = t If b < c Then t = b: b = c: c = t = c: = b: = a End Sub
18．在窗体上画两个命令按钮分别求11+22+33+44+……+nn小于100000最大值和
?n!?1!?2!?3!??n?120?20!Private Sub Command1_Click() n = 0: s = 0 Do
n = n + 1 s = s + n ^ n = s
Loop Until s > 100000 End Sub
Private Sub Command2_Click() s = 0
的累加和并将结果输出到Label1和Label2中。
For i = 1 To 20 n = 1
For k = 1 To i n = n * k Next k s = s + n Next i = s End Sub
19．在窗体上画两个文本框输入a和n的值（a和n均为一位数字），单击命令按钮输出
Sn=a+aa+aaa+aaaa+…+aa…a（最后一项n个a，例如3+33+333+3333）的值于标签中。Private Sub Command1_Click() b = String(i, a) a = Sn = Sn + Val(b) n = Val(Text2) Next i Sn = 0 = Sn For i = 1 To n End Sub
20．单击命令按钮将3到200之间的所有奇数显示在列表框中。Private Sub Command1_Click() Next i For i = 3 To 200 Step 2 End Sub i
21．在窗体上画一文本框用于输入n值，画两个命令按钮分别求下述表达式的值
S1=4?(1?1?1???(?1)n?11)352n?1Private Sub Command1_Click()
n = Val(Text1) s = 0
For i = 1 To n
s = s + (-1) ^ (i + 1) / (2 * i - 1) Next i S2 = 1
S2=1×3×5×7×…×(2n-1)并将S1、S2的结果输出到图片框。
For i = 1 To n
S2 = S2 * (2 * n - 1) Next i 4 * s S2 End Sub
22．在文本框T1中打印100~999之间的所有水仙花数。 （该数为各位数字的立方和。例如：153=1 3+5 3+3 3 ）
Private Sub Command1_Click() For i = 100 To 999 a = Fix(i / 100)
b = Fix(i / 10) - a * 10 c = i - Fix(i / 10) * 10
If a ^ 3 + b ^ 3 + c ^ 3 = i Then = & i & vbCrLf Next i End Sub
23．有一数列，它的头2个数为0、 1，以后的每个数都是其前2个数之和。编程在文本框T1中输出所有这些数列，直到第30个数或最后一项等于1000为止，同时在另一文本框中输出它们的和。
Private Sub Command1_Click() a = 0: b = 1: s = 0
= a & vbCrLf & b & vbCrLf For i = 1 To 14
s = s + a + b a = a + b b = a + b
= & a & vbCrLf & b & vbCrLf
Next i = s
End Sub
24．设计如下图所示界面，单击时输出相应结果，2~N之间素数在列表框中输出，要求判断素数用过程实现。
Function h(a As Integer) As Boolean Dim m As Integer, s As Boolean m = 0
For i = 2 To (a - 1)
If a Mod i = 0 Then m = m + 1 Next i
If m = 0 Then s = True Else s = False h = s
End Function
Private Sub Command1_Click() Dim a As Integer a = Val(Text1)
If h(a) = False Then
= \不是素数\ Else
= \是素数\End If End Sub
Private Sub Command2_Click() Dim i As Integer a = Val(Text1) For i = 2 To a
If h(i) = True Then i Next i End Sub
25．界面如上图，单击各按钮时输入行数，按此行数在窗体上显示不同的图形（参
考教材练习6-15）。
Private Sub Command1_Click() Cls
a = Val(InputBox(\请输入行数\For i = 1 To a
Print Tab(i); String(a, \Next i End Sub
Private Sub Command2_Click() Cls
a = Val(InputBox(\请输入行数\For i = 1 To a
Print Tab(a - i + 1); String(2 * i - 1, \ Next i End Sub
Private Sub Command3_Click() Cls
a = Val(InputBox(\请输入行数\For i = a To 1 Step -1
Print Tab(a - i + 1); String(2 * i - 1, \ Next i End Sub
Private Sub Command4_Click() Cls
a = Val(InputBox(\请输入行数\For i = a To 1 Step -1
Print Tab(a - i + 1); String(2 * i - 1, \
Space(3); String(2 * (a - i) + 1, \ Next i
End Sub
26．设计如下图所示界面，单击时输出N!和1!+2!+…+N!结果，要求N!用过程实现。
Function h(n As Integer) As Integer Dim s As Integer s = 1
For i = 1 To n s = s * i Next i h = s
End Function
Private Sub Command1_Click() Dim n As Integer n = Val(Text1)
= h(n) End Sub
Private Sub Command2_Click() Dim n As Integer m = Val(Text1) s = 0
For n = 1 To m s = s + h(n) Next n = s End Sub
27． 编写一个程序，输出一个5*5的矩阵，该矩阵主、负对角线上元素均为1，其余元素均为2，执行结果如上图所示。Option Base 1
Dim A(5, 5) As Integer Private Sub Form_Click() For i = 1 To 5 For j = 1 To 5 A(i, j) = 2
If i = j Then A(i, j) = 1 If i + j = 6 Then A(i, j) = 1
Next j, i For i = 1 To 5 CurrentY = i * 300 For j = 1 To 5 CurrentX = j * 300 Print A(i, j); Next j, i End Sub
28．界面如下图所示。分别在Textl和Text2中输入两个自然数x、y，用展转相除的方法求自然数x，y的最大公约数和最小公倍数。在窗体上显示结果。
Dim a As Integer, b As Integer, x As
Integer, y As Integer,r as Integer
Private Sub Command1_Click() x = Val(Text1)
y = Val(Text2) a = x: b = y r = x Mod y Do While r <> 0 x = y
y = r
r = x Mod y Loop = y End Sub
Private Sub Command2_Click() = a * b / y End SubText1 Text2 Label3 Label4
29．仿照25题画四个命令按钮，单击各按钮在图片框上显示如下不同的数据图形。
Private Sub Command1_Click() For i = 1 To 6
For j = i To 1 Step -1 Print j; Next j Print Next i End Sub
Private Sub Command2_Click() For i = 6 To 1 Step -1 Print Space(18 - 3 * i); For j = 1 To i Print j; Next j Print Next i End Sub
Private Sub Command3_Click() For i = 1 To 6
Print Space(18 - 3 * i); For j = i To 1 Step -1 Print 7 - j; Next j Print Next i End Sub
Private Sub Command4_Click() For i = 6 To 1 Step -1 For j = i To 1 Step -1 Print j; Next j Print Next i
End Sub
30．设计一个窗体Forml，编写适当的事件过程。控制Text1中背景色和字体格式。
VB上机练习题
