什么情况下需要使用模块文件呢??

需要使用公共变量或公共函数的时候
比如下面的函数在程序中经常会用到，
可以放在模块里

Public Function Min(ParamArray vals())
Dim i
Min = vals(0)
For i = 1 To UBound(vals)
If Min > vals(i) Then Min = vals(i)
Next i
End Function

Public Function Max(ParamArray vals())
Dim i
Max = vals(0)
For i = 1 To UBound(vals)
If Max < vals(i) Then Max = vals(i)
Next i
End Function

Public Function GetDivisor(ByVal m As Long, ByVal n As Long) As Long
'辗转相除法求m/n的公约数
Dim t As Long
If m < n Then Swap m, n
Do Until n = 0
t = m Mod n
m = n
n = t
Loop
GetDivisor = m
End Function

Public Function GetPow(ByVal m As Long, ByVal n As Long) As Long
'求m中n的幂次
Dim num As Long
Do While m Mod n = 0
m = m / n
num = num + 1
Loop