编写程序，求S = (A! + B!)/C!，阶乘的计算分别用Sub过程和Function过程两种方法来实现。

定义函数 ： 计算n的阶乘
long fac(int n)
{if(n==0)
return(1l);
else
return(n*fac(n-1));}
过程用循环实现
a=a*b
s=s+a

sub实现：

Private Sub Command1_Click()
Dim a As Long, b As Long, c As Long
a = Val(InputBox("请输入一个大于0的整数A："))
b = Val(InputBox("请输入一个大于0的整数B："))
c = Val(InputBox("请输入一个大于0的整数C："))
If a > 0 And b > 0 And c > 0 Then
n1 a
n1 b
n1 c
MsgBox "A!+B!+C!=" & a + b + c
End If
End Sub

Sub n1(n As Long)
Dim i As Long, s As Long
s = 1
For i = 2 To n
s = s * i
Next
n = s
End Sub

function实现：

Private Sub Command1_Click()
Dim a As Long, b As Long, c As Long
a = Val(InputBox("请输入一个大于0的整数A："))
b = Val(InputBox("请输入一个大于0的整数B："))
c = Val(InputBox("请输入一个大于0的整数C："))
If a > 0 And b > 0 And c > 0 Then