20道 vb习题答案

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

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，找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。编程找出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，请找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，若找不到，则输出“查找失败”。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