20道 vb习题答案
二、编程题
1. 输入三角形的三条边a，b，c的值，根据其数值，判断能否构成三角形。若能则求出三角形的面积。
Private Sub Command1_Click()
Dim a As Integer, b As Integer, c As Integer
Dim s As Single, area As Single
a = InputBox("请输入边长a")
b = InputBox("请输入边长b")
c = InputBox("请输入边长c")
If a + b > c And a + c > b And b + c > a Then
Print "能构成三角形"
s = (a + b + c)  / 2
area = Sqr(s * (s–a)  * (s–b)  * (s-c )
Print "面积为："; area
Else
Print "不能构成三角形"
End If
End Sub
2. 编一程序：根据上网时间计算上网费用。计算的方法如下：为了鼓励多上网，每月收费最多不超过100元。
30元基数        ＜10 h
费用＝
每小时2元      10～60 h
每小时1.5元    ＞60 h
Private Sub Command1_Click()
Dim a As Integer, page As Single
a = Val(InputBox("请输入上网的时长"))
If a > 0 Then
Select Case a
Case Is < 10
page = 30
Case Is < 60
page = a * 2
Case Else
page = a * 1.5
End Select
Else
MsgBox "没有上网，无需交费"
End If
If page > 100 Then page = 100
Print "您本月共上网"; a; "小时，需交费："; page; "元"
End Sub
3. 有一个长阶梯，如果每步跨2阶最后剩1阶，如果每步跨3阶最后剩2阶，如果每步跨4阶最后剩3阶，如果每步跨5阶最后剩4阶，如果每步跨6阶最后剩5阶，只有当如果每步跨7阶时恰好走完，问这个阶梯至少有多少阶?
Private Sub Command1_Click()
Dim a As Integer, i As Integer
Do While True
i = i + 1
vb程序设计教程第二版答案If i Mod 2 = 1 And i Mod 3 = 2 And i Mod 4 = 3 And i Mod 5 = 4 And i Mod 6 = 5  _And i Mod 7 = 0 Then
Print "该阶梯至少有"; i; "阶"
Exit Do
End If
Loop
End Sub
4. 一个球从100 m高度自由下落，每次落地后反跳回原高度的一半，再落下。求它在第10次落地时，共经过多少m？最后一次反弹高度多少？
Private Sub Command1_Click()
Dim i As Integer, s As Single, h As Single
h = 10
For i = 2 To 10
s = s + h
h = h / 2
s = s + h
Next i
Print "共经过"; s; "米。最后一次反弹高度为"; h
End Sub
5. 有一根长度为321m的钢材料，要将它截取成两种规格的短料，规格a、b的长度分别为17 m和27 m，问分隔成a、b各多少段后，剩余的残料r最少？
Private Sub Command1_Click()
Dim i As Integer, r As Integer, a As Integer, b As Integer，min As Integer
min = 17
For i = 0 To 11
r = (321 - 27 * i) Mod 17
If r < m
in Then min = r: a = i: b = (321 - 27 * i) / 17
Next i
Print r, a, b
End Sub
6. 小猴在一天摘了若干个桃子，当天吃掉一半多一个；第二天接着吃了剩下的桃子中的一半多一个，以
后每天都吃剩下桃子中的一半零一个，到第7天早上要吃时只剩下一个了，问小猴那天共摘下了多少个桃子？
Private Sub Command1_Click()
Dim i As Integer, s As Integer
s = 1
For i = 6 To 1 Step -1
s = (s + 1) * 2
Next i
Print s
End Sub
7. 某次大奖赛，有7个评委打分，满分为100分。对一名参赛者，输入7个评委的打分分数，去掉一个最高分、一个最低分后，求出平均分为该参赛者的得分。编写程序输入评委的打分，输出参赛者的得分。
Private Sub Command1_Click()
Dim Max As Integer, min As Integer
Dim i As Integer, s As Integer, f As Integer
Max = 0
min = 100
For i = 1 To 7
f = InputBox("请输入评委的打分")
If f > Max Then Max = f
If f < min Then min = f
s = s + f
Next i
aver = (s - Max - min) / 5
Print "参赛者最后得分为："; aver, Max, min
End Sub
8. 输入任意长度的字符串，要求将字符顺序倒置，例如，将输入的“ABCDEFG”变换成“GFEDCBA”。
Private Sub Command1_Click()
Dim str1 As String, str2 As String
Dim i As Integer, k As Integer
str1 = InputBox("")
str2 = ""
k = Len(str1)
For i = k To 1 Step -1
str2 = str2 + Mid(str1, i, 1)
Next i
Print str2
End Sub
9. 由键盘输入一个正整数，出大于或等于该数的第一个质数。
Private Sub Command1_Click()
Dim i As Integer, x As Integer, j As Boolean
x = InputBox("请输入一个数")
Do While True
x = x + 1
For i = 2 To Sqr(x)
j = True
If x Mod i = 0 Then j = False: Exit For
Next i
If j Then Exit Do
Loop
Print x
End Sub
10. “完备数”是指一个数恰好等于它的因子之和，如6的因子为1、2、3，而6=1+2+3，因而6就是完备数。编程出1～1000之间的全部“完备数”。
Private Sub Command1_Click()
Dim i As Integer, a As Integer
Dim s As Integer
For i = 1 To 1000
a = 2: s = 1
Do While a < i
If i Mod a = 0 Then
s = s + a
End If
a = a + 1
Loop
If s = i Then
Print i
End If
Next i
End Sub
11. 勾股定理中三个数的关系是：a^2 + b^2 =c^2。编写程序，输出100以内满足上述关系的整数组合，例如3，4，5就是一个整数组合。
Private Sub Command1_Click()
Dim a As Integer, b As Integer, c As Integer
For a = 1 To 100
For b = a To 100
For c = b To 100
If a ^ 2 + b ^ 2 = c ^ 2 Then
Print "勾股定理整数组合"; a, b, c
End If
Next c
Next b
Next a
End Sub
12. 编写程序，打印如下的乘积表：
    *    3    6    9    12
    15
    16
    17
    18
Private Sub Command1_Click()
Dim i As Integer, j As Integer
Print "  *    3      6      9      12"
For i = 15 To 18
Print i; "  ";
For j = 3 To 12 Step 3
Print i * j; "  ";
Next j
Print
Next i
End Sub
13. 一个两位正整数，如果将它的个位数字与十位数字对调，则产生另一个正整数，我们把后者叫做前
者的对调数。现给定一个两位正整数，请到另一个两位正整数，使得这两个两位正整数之和等于它们各自的对调数之和，若不到，则输出“查失败”。例如：32+12=21+23。（要求：在程序运行时从键盘输入给定的两位正整数）
Private Sub Command1_Click()
Dim a As Integer, b As Integer, c As Integer, d As Integer
Dim i As Integer, j As Integer, k As Integer, l As Integer
a = InputBox("")
i = a \ 10
j = a Mod 10
c = j * 10 + i
For b = 10 To 99
k = b \ 10
l = b Mod 10
d = l * 10 + k
If a + b = c + d Then Print a; "的对调数为"; b
Next b
End Sub
14. 有一数列：1、1、2、3、5、8、13、21…，求出这个数列的前20项之和。
Private Sub Command1_Click()
Dim f1 As Single, f2 As Single, f3 As Single
Dim i As Integer, j As Integer, n As Integer
Dim sum As Single
f1 = 1
f2 = 1
sum = 2
Do While i <= 20-3
f3 = f1 + f2
f1 = f2
f2 = f3
sum = sum + f3
i = i + 1
Loop
Print sum
End Sub
15. 把一个16进制数转换成一个10进制数。
Private Sub Command1_Click()
Dim a As Integer, k As String, h As Integer, s As Integer
a = InputBox("请输入一个16进制数")
k = Trim(Str(a) )
h = Len(k)
s = a Mod 10
For i = h-1 To 1 Step-1
s = s + Val(Mid(k, i, 1)) * 16 ^ (h-i)
Next i
Print "16进制数："; a; "转换为10进制数是："; s
End Sub
16. 编写程序，单击窗体时在窗体上打印出如下所示的图形。
*
***
*****
*******
*********
*******
*****
***
*
Private Sub Command1_Click()
Dim i As Integer, j As Integer
j = j + 1
For i = -4 To 4
Print Tab(20 + Abs(i));
For j = 1 To 9 -Abs(2 * i)
Print "*";
Next j
Print
Next i
End Sub
17. 编写程序，输出下列三角形： (要求用循环做，非循环不给分)
G
FG
EFG
DEFG
CDEFG
BCDEFG
ABCDEFG
Private Sub Command1_Click()
Dim a As String, b As String, i As Integer, j As Integer
Dim s As Integer, t As Integer, k As Integer, m As Integer
a = "ABCDEFG"
k = Len(a)
For i = 1 To k
Print Right(a, i)
Next i
End Sub
18. 编程输入一批数据，若输入数据为纯数字时，求累加和，非纯数字不累加
。输入"Y"结束输入，输出累加和。(用InputBox()输入数据)
Private Sub Command1_Click()
Dim x, s As Single, bz As String
Do While UCase(bz) < > "Y"
x = InputBox("请输入相加的值")
If Val(x) = x Then
s = s + x
End If
bz = InputBox("是否结束？(Y/N)")
Loop
Print s
End Sub
19. 求公式：e=1+1/1!+1/2!+1/3!+……+1/n! 直到n=20时的e值。
Private Sub Command1_Click()
Dim i As Integer, j As Integer
Dim s As Single, h As Single, l As Single, k!
k = 1
s = 1
For i = 1 To 20
k = k * i
s = s + 1 / k
Next i
Print s
End Sub
20. 已知sin(x)=x/1-x^3/3!+x^5/5!-x^7/7!+…，设计一个程序，输入x，通过累加所有绝对值大于等于0.000001的项来计算sin(x)的值。
Private Sub Command1_Click()
Dim i As Integer, j As Integer
Dim x As Single, sum As Single
Dim h As Single, k As Single
x = InputBox("请输入x的值")
h = 1
k = 1
Do
i = i + 1
h = h * x
k = k * i
If i Mod 2 = 1 Then
j = j + 1
sum = sum + (-1) ^ (j + 1) * h / k
End If
Loop While Abs(h / k) > 10 ^ (-6)
Print sum
End Sub

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