VB编程程序练习题.doc

文档介绍：VB编程练****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 mand1_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:已知x、y、z分别是0~9中的一个数,求x、y、z的值,使得下列成立:
xxz+yzz=532。(其中xxz和yzz不表示乘积,而是由x、y、z组成的三位数)。
Private mand1_Click()
Dim x, y, z
For x = 1 To 9
For y = 1 To 9
For z = 1 To 9
If (100 * x + 10 * x + z) + (100 * y + 10 * z
+ z) = 532
Then
Print x, y, z;
End If
Next z
Next y
Next x
End Sub
3、* 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 mand1_Click()
Dim i As Integer, n As Integer, sum As Integer
n = Val()
For i = 1 To n
sum = sum + i * (i + 1)
Next i                                 
Print sum
End Sub
4、* 编写程序:编程计算1-2+3-4+5-6…±n的值,n由用户输入
Private mand1_Click()
Dim s As Integer, a As Integer, i As Integer
n = Val()
s = 0: a = 1
For i = 1 To n
s = s + i * a
a = -a
Next i
Print s
End Sub
5、* 编写程序:编程计算1+(1+2)+(1+2+3)+…+(1+2+3…+n),n由用户输入。
Private mand1_Click()
n = Val()
Sum = 0
For i = 1 To n
sum1 = 0
For j = 1 To i
sum1 = sum1 + j
Next j
Sum = Sum + sum1
Next i
Print Sum
End Sub
6  * 编写程序: * 计算并输出下面级数前n项(n=30)的部分和。
              1/(1*2)+1/(2*3)+1/(3*4)+…+1/(n*(n+1))+ ……
Private mand1_Click()
Dim i As Integer, n As Integer, sum As Integer
For i = 1 To 30
sum = sum + i * (i + 1)
k = 1 / sum
w = w + k
Next i
Print w
End Sub
7、* 编写程序: * 求出斐波那契数列前20项中的奇数项的和。
* 提示:前两项为:0,1,从第3项开始,每一项均为其前两项的和(即:0+1+1+2+3+5+...)。
Private mand1_Click()
Dim a%, b%, c%, d%
a = 0: b = 1
For d = 1 To 18
c = a + b
a = b
b = c
If d Mod 2 = 1