Question

有关VB for循环的习题（求过程，最好结合讲解）

1.用100元买100只鸡，母鸡每只2元，公鸡每只1元，小鸡每只0.5元。 求各种买法，打印出来。
2.用两种方法算 （n！分之一）的和
100元要刚好用完饿。。 第二题呢？ 我会追加的。。谢谢

Answer 1

楼上regnad 的买鸡有问题

Private Sub Command1_Click()
'用100元买100只鸡，母鸡每只2元，公鸡每只1元，小鸡每只0.5元
'等价:用200元买100只鸡，母鸡每只4元，公鸡每只2元，小鸡每只1元
'避免小数运算
Dim 母鸡 As Integer, 公鸡 As Integer, 小鸡 As Integer
For 母鸡 = 0 To 50
For 公鸡 = 0 To 100
小鸡 = 100 - 母鸡 - 公鸡
If 200 = 4 * 母鸡 + 2 * 公鸡 + 1 * 小鸡 Then _
Debug.Print "母鸡:" & 母鸡 & "只，公鸡:"; 公鸡 & "只，小鸡:" & 小鸡 & "只"
Next 公鸡
Next 母鸡
End Sub
---------------------------------------------
Private Sub Command1_Click()
'（n!分之一）的和
'方法1
Dim i As Double, j As Double
Dim t As Double
Dim n As Double
n = Val(InputBox(""))
t = 0
j = 1
For i = 1 To n
j = j * i
t = t + 1 / j
Next i
Debug.Print t
End Sub
---------------------------------------------
Private Sub Command1_Click()
'（n!分之一）的和
'方法2
Dim i As Double
Dim n As Double
Dim t As Double
n = Val(InputBox(""))
t = 0
For i = 1 To n
t = t + 1 / Factorial(i)
Next i
Debug.Print t
End Sub

Private Function Factorial(ByVal n As Double) As Double
'返回n的阶乘
Dim i As Double, t As Double
t = 1
For i = 1 To n
t = t * i
Next i
Factorial = t
End Function

Answer 2

第一题
Dim total As Double
Const pM As Double = 5, pG As Double = 1, pX As Double = 0.5
For cm = 0 To 100
For cg = 0 To 100 - cm
cx = 100 - cm - cg
total = cm * pM + cg * pG + cx * pX
If total=100 Then Debug.Print "母鸡:" & cm & "公鸡:" & cg & "小鸡:" & cx & "总价:" & total

Next
Next

第二题(自己改一下):
'以下是写入了Form_Load事件中,仅仅是测试'
Private Sub Form_Load()
Dim c As Double
c = 0
For i = 0 To 999
'你要算到哪一项?
c = c + 1 / fn(i)
Next
Debug.Print "结果:" & c
Stop

End Sub
'以下是函数,同样写在过程外面
Function fn(ByVal n As Integer) As Long
Dim temp As Long
temp = 1
For i = 1 To n
temp = temp * i
Next
fn = temp
End Function