VB程序设计 习题及答案第5章 循环结构程序设计

1、.第5章 循环结构程序设计 51 试编程序，打印出自然数1到20的立方数。【参考答案】程序代码设计Private Sub Form_Click() Form1.Print " x", " x2" For x = 1 To 20 Form1.Print x, x 2 Next xEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "打印自然数1到20的立方数" Form1.Print "单击窗体开始"End Sub

2、图5-1 程序运行结果程序运行结果如图5-1所示： 52 试编程序，打印出1到500之间所有偶数的和。【参考答案】程序代码设计Private Sub Command1_Click() Sum = 0 For k = 1 To 500 If k Mod 2 = 0 Then Sum = Sum + k Next k Form1.Print "1到500的偶数和为：" SumEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print Form1.Print "打印1到500

3、之间所有偶数的和" Form1.Print图5-2 程序运行结果End Sub程序运行结果如图5-2所示： 53 试编写打印下面图案的源程序。 * * * * * * * * * * * * * * *【参考答案】程序代码设计Private Sub Command1_Click() For i = 1 To 5 Form1.Print Tab(5 + i); For j = i To 5 Form1.Print "*" Next j Form1.Print Next iEnd Sub程序运行结果如图5-3所示： 图5-3 程序运行结果 

4、;54 试编写打印下面图案的源程序。 * * * * * * * * * * * * * * * * * * * * * * * * * 【参考答案】程序代码设计Private Sub Command1_Click() For i = 1 To 4 Form1.Print Tab(10 - i); For j = 1 To 2 * i - 1 Form1.Print "*" Next j Form1.Print Next i For k = 3 To 1 Step -1 Form1.Print Tab(10 - k); For j = 1 To 2 * k - 1

5、 Form1.Print "*" Next j Form1.Print图5-4 程序运行结果 Next kEnd Sub程序运行结果如图5-4所示： 55 编写程序，计算下面表达式的值（1）1!+3!+5!+(2N+1)!【参考答案】程序代码设计Private Sub Command1_Click() n = Val(InputBox("请输入N值") Sum = 1 term = 1 For k = 3 To 2 * n + 1 Step 2 term = term * (k - 1) * k Sum = Sum + term Next k

6、Form1.Print "1!+3!+5!+(2N+1)!=" Sum图5-5（1）程序运行结果End Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算1!+3!+5!+(2N+1)!"End Sub运行结果:若n输入的值为5,则程序运行结果如图5-5（1）所示。 （2）1+X/2!+X2/4!+X3/6!+XN/(2N)!【参考答案】程序代码设计Private Sub Command1_Click() x = Val(InputBox("

7、请输入x值") n = Val(InputBox("请输入N值") Sum = 1 t1 = 1 t2 = 1 For k = 2 To 2 * n Step 2 t1 = t1 * x t2 = t2 * (k - 1) * k Sum = Sum + t1 / t2 Next k Form1.Print "1+X/2!+X2/4!+XN/(2N)!=" SumEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算1+X/2!+X2/4

8、!+XN/(2N)!"End Sub运行结果：图5-5（2）程序运行结果若x输入值为：1.5,n输入值为:5,则程序运行结果如图5-5（2）所示。 （3）1+1×3+1×3×5+1×3×(2N+1)【参考答案】程序代码设计Private Sub Command1_Click() n = Val(InputBox("请输入N值") Sum = 1 term = 1 For k = 3 To 2 * n + 1 Step 2 term = term * k Sum = Sum + term Next k Fo

9、rm1.Print "1+1×3+1×3×5+1×3×(2N+1)=" SumEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算1+1×3+1×3×5+1×3×(2N+1)"End Sub运行结果:若n输入值为5,则程序运行结果如图5-5（3）所示：    图5-5（3）程序运行结果  （4）x-

10、x3/3!+x5/5!-x7/7!+【参考答案】程序代码设计Private Sub Command1_Click() x = Val(InputBox("请输入x值") Sum = x t1 = x t2 = 1 f = 1 k = 1 While (t1 / t2 > 0.0001) k = k + 2 t1 = t1 * x * x t2 = t2 * (k - 1) * k图5-5（4）程序运行结果 f = f * (-1) Sum = Sum + f * t1 / t2 Wend Form1.Print "x-x3/3!+x5/5!-x7/7!+=&

11、quot; SumEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算x-x3/3!+x5/5!-x7/7!+"End Sub运行结果:若x输入值为:1.5, 则程序运行结果如图5-5（4）所示： （5）1+1/2+1/3+1/N （1/N<10-4）【参考答案】程序代码设计Private Sub Form_Click() Sum = 0 k = 1 While (1 / k > 0.0001) Sum = Sum + 1 / k k = k + 1 W

12、end Form1.Print "1+1/2+1/3+1/N=" SumEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算1+1/2+1/3+1/N" Form1.Print "单击窗体开始"End Sub程序运行结果如图5-5（5）所示：图5-5（5）程序运行结果  5.6 由随机函数产生10道一位整数与两位整数相加的加法题，产生的加法题依次显示在屏幕上，每产生一道题后，由用户输入答案，如果答案正确，记10分；如

13、果答案错误，允许第二次输入答案，第二次输入答案正确，记5分，错误记0分。最后给出总得分。【参考答案】程序代码设计Private Sub Form_Click() s = 0 For i = 1 To 10 a = Int(10 * Rnd) b = Int(10 + 90 * Rnd) str1$ = "第" & i & "题 " & a & "+" & b c = Val(InputBox(str1$ & " 第一次回答") If a + b = c Then s

14、= s + 10 str2$ = str1$ & " 10分" Else c = Val(InputBox(str1$ & " 第二次回答") If a + b = c Then s = s + 5 str2$ = str1$ & " 5分" Else str2$ = str1$ & " 0分" End If End If Form1.Print str2$ Next i Form1.Print "总分" sEnd Sub Private Sub For

15、m_Load() Form1.AutoRedraw = True Form1.Print "加法题，第一次回答正确10分，" Form1.Print "第二次回答正确5分" Form1.Print "单击窗体开始"End Sub图5-6 程序运行结果程序运行结果如图5-6所示： 5.7 编写计算还贷款年限的程序，从贷款的第三年开始还贷，贷款年利按复利计算。贷款额10万元，年利率7%，每年还款数3万元，要求输出经过多少年才能还清贷款，以及最后一年的还款数。【参考答案】程序代码设计Private Sub Form_Click()

16、 Dim p As Single p = 10 r = 0.07 n = 0 While (p > 0) p = p * (1 + r) n = n + 1 If n >= 3 Then p = p - 3 Wend Form1.Print "还清贷款时间" & n; "年" Form1.Print "最后一年的还款数" & (3 + p) & "万"End Sub Private Sub Form_Load() Form1.AutoRedraw = True Form

17、1.Print "贷款额10万元，年利率7%" Form1.Print "计算还贷数据" Form1.Print "单击窗体开始"End Sub图5-7 程序运行结果程序运行结果如图5-7所示： 5.8 输入三角形的三条边A、B、C，根据A、B、C的数值判断三角形的性质，并给出如下信息：（1）等边三角形；（2）等腰三角形；（3）任意三角形；（4）不能构成三角形。【参考答案】(1)用户界面设计(2)控件属性设置(略)(3)程序代码设计Private Sub Command1_Click() a = Val(Text1.Text

18、) b = Val(Text2.Text) c = Val(Text3.Text) If (a = b And b = c) Then str1 = "等边三角形" ElseIf (a = b Or b = c Or c = a) Then str1 = "等腰三角形" ElseIf (a + b <= c Or b + c <= a Or c + a <= b) Then str1 = "不能构成三角形" Else str1 = "任意三角形" End If Label2.Caption = s

19、tr1End Sub图5-8程序运行结果程序运行结果如图5-8所示。 59 一个球从10米的高处落下，它每次反弹的高度为前一次下落高度的2/3，编写程序计算球第10次落地时运动的总路程。【参考答案】程序代码设计Private Sub Form_Click() h = 10 s = h For i = 1 To 9 h = h * 2 / 3 s = s + 2 * h Next i s = CInt(100 * s) / 100 Form1.Print "球第10次落地时的总路程为" s; "米"End Sub图5-9 程序运行结果 

20、 Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算球第10次落地时的总路程" Form1.Print "单击窗体开始"End Sub程序运行结果如图5-9所示。 510 编写程序把一个分数化为最简分数。对一个分数化简，实际是要寻找分子N与分母M的最大公因子。【参考答案】程序代码设计Private Sub Command1_Click() Dim m As Integer, n As Integer, u As Integer, v As Integer m

21、= Val(Text1.Text) n = Val(Text2.Text) If m > n Then u = m: v = n Else v = m: u = n End If Do r = u Mod v u = v: v = r Loop Until r = 0 m = m / u: n = n / u Label2.Caption = "化简后分子 " & m & " , 分母 " & nEnd Sub程序运行结果如图5-10所示：图5-10 程序运行结果  511 幼儿园的小朋友分吃一堆糖果。第

22、一天吃了一半，又吃了一颗；第二天，同样吃了剩下的一半，又多吃了一颗。到第十天一看，只剩一颗糖果。问原来共有多少颗糖果。【参考答案】程序代码设计Private Sub Form_Click() num = 1 For k = 9 To 1 Step -1 num = (num + 1) * 2 Next k Form1.Print "糖果数为" numEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "计算糖果数" Form1.Print "单击窗体开

23、始"End Sub程序运行结果如图5-11所示： 图5-11 程序运行结果 512 求解方程X3+Y3-Z3=3，其中X、Y、Z均为正整数，且X、Y、Z均1，同时X、Y、Z均6。【参考答案】程序代码设计Private Sub Form_Click() For x = 1 To 6 For y = 1 To 6 For z = 1 To 6 If x 3 + y 3 - z 3 = 3 Then Form1.Print x; y; z End If Next z Next y Next xEnd Sub图5-12程序运行结果 Private Sub For

24、m_Load() Form1.AutoRedraw = True Form1.Print "解方程X3+Y3-Z3=3" Form1.Print "单击窗体开始"End Sub程序运行结果如图5-12所示： 513 36块砖，36人搬，男搬4、女搬3、两个小儿抬一砖，要求一次全搬完，问男、女、小儿需若干？方程：x+y+z=36 4*x+3+y+z/2=36【参考答案】程序代码设计Private Sub Form_Click() For x = 1 To 36 For y = 1 To 36 For z = 1 To 36 If x + y +

25、z = 36 And 4 * x + 3 * y + z / 2 = 36 Then Form1.Print x; y; z End If Next z Next y Next xEnd Sub Private Sub Form_Load() Form1.AutoRedraw = True Form1.Print "男、女、小儿需若干" Form1.Print "单击窗体开始"图5-13程序运行结果End Sub程序运行结果如图5-13所示： 514 打印出3100之间的所有素数（质数）。【参考答案】程序代码设计Private Sub Form_Click() k = 0 For n = 3 To 100 For i = 2 To n - 1 If n Mod i = 0 Then Exit For Next i If i > n - 1 Then k = k + 1: