VB程序设计题:编写程序，计算N!的值(N为键盘输入的一个整数)

Private Sub Command1_Click()
Dim XX As Double, YY As Integer
XX = 1
YY = Val(InputBox("请输入N的值", "输入", 0))

If YY > 170 Then
MsgBox "你输入的值太大，最大只能计算170的阶乘值！"
YY = 170
End If
For I = 1 To YY
XX = XX * I
Next I
Text1.Text = YY & " 的阶乘 = " & CStr(XX)
End Sub

Private Sub Command1_Click()

    Dim i As Integer, n As Integer, s As Double

    s = 1

    n = Val(Text1.Text)

    If n <= 1 Then

        Text2.Text = "1"

        Exit Sub

    Else

        For i = 1 To n

            s = s * i

        Next i

        Text2.Text = Format(s, "0")

    End If

End Sub

Private Sub Form_Load()

    Text1.Text = ""

    Text2.Text = ""

    Command1.Caption = "计算"

End Sub

‘调用示例
Private Sub Form_Load()
MsgBox fun_JC(3)

End Sub

'阶乘函数
Private Function fun_JC(ByVal N As Integer) As Long
Dim i As Integer
Dim l As Long
l = 1
If N <= 1 Then
fun_JC = 1
Exit Function
End If

For i = N To 2 Step -1
l = l * i
Next
fun_JC = l

End Function