VB编程:求1!+2!+3!+...+N!(N为任意正整数)

Private Function cacl(num As Long) As String
Dim numlen As Long, last As Long, x As Long
Dim i As Long, m As Long, n As Long, nl As Long, s0 As String
Dim result() As Long, starttime As Single, s() As String
numlen = 1
starttime = Timer
ReDim result(1 To numlen)
nl = 9 - Len(CStr(num)) '根据两数相乘最大得数长度，不会超过两数长度总和的原理，
'让数组中每个元素长度与阶乘数长度之和不能超过9，以防止溢出。
If nl < 1 Then nl = 1 '最小长度是1位，若真到了这么大的数，恐怕没人会去试了^-^
n = 10 ^ nl '缓存用于分隔大数的被除数，数组中每个元素的长度是 nl，该数就是10的 nl 次方
result(1) = 1
x = 1
Do While x <= num
last = 0
For i = 1 To numlen
m = result(i) * x + last '数组中每个元素进行与待乘数相乘后，再加上上次进位数
result(i) = m Mod n '分隔大数
last = m \ n '保存进位数并等待累计进下一个数组元素
Next
If last > 0 Then
m = Len(CStr(last)) \ nl + 1 '对超过数组元素上限的进位数要增加数组大小，并按长度nl分隔
ReDim Preserve result(1 To numlen + m)
For i = 1 To m
result(numlen + i) = last Mod n
last = last \ n
Next
numlen = UBound(result)
End If
x = x + 1
Loop
ReDim s(1 To numlen)
s0 = String(nl, "0") '对长度不足nl的数组元素要在前面补0，不然结果就在错特错了
For i = 1 To numlen
s(i) = Format(result(numlen + 1 - i), s0) '格式化补 0 每个数组元素
Next
s(1) = Val(s(1))
If s(1) = 0 Then s(1) = "" '最高位要去掉0，虽对得数没影响，但位数会错。
cacl = Join(s, "")
Debug.Print num & "！ ： 用时 "; Timer - starttime & " 秒, 结果 " & Len(cacl) & " 位"
End Function

Private Sub Command1_Click()
Dim i As Long
Dim n As Long
Dim t As Double
n = InputBox("输入N值")
For i = 1 To Val(n)
t = t + Val(cacl(i))
Next
Print "1!+2!+3!+...+" & n & "!="; t
End Sub
呵呵 改进速度的 10000！只需10秒

'在窗体上加入一个command1控件，然后复制下面代码，运行即可。
Option
Explicit
Private
Sub
Command1_Click()
Dim
i
As
Long,
j
As
Long,
k
As
Long
Dim
s
As
Long,
a
As
Long
j
=
InputBox("请输入一个正整数：")
If
j
<
1
Then
MsgBox
"出错！"
Exit
Sub
End
If
For
i
=
1
To
j
a
=
1
For
k
=
1
To
i
a
=
a
*
k
Next
s
=
s
+
a
Next
MsgBox
"1!+2!+3!+...+N!="
&
s
End
Sub

输个1000进去，楼上两位的都得溢出。
这个链接是讨论版(不含源码)：http://bbs.bccn.net/viewthread.php?tid=148409&extra=&highlight=%2Bjoforn&page=19
源码在这个链接中：http://bbs.bccn.net/viewthread.php?tid=157144&highlight=%2Bjoforn
里面有好多种不同方式实现的。