急用!编一个判断某数是否为素数的vb函数程序,返回值是逻辑型

Dim m As Integer
Private Sub Command1_Click()
a = InputBox("请输入数字")
For i = 1 To Val(a)
If a Mod i = 0 Then m = m + 1
Next
If m = 2 Then
Print "true"
Else
Print "false"
End If
m = 0
End Sub
查找小于某数的最大素数
Dim m As Integer
Private Sub Command1_Click()
a = InputBox("请输入数字")
For j = Val(a) - 1 To 1 Step -1
For i = 1 To j
If j Mod i = 0 Then m = m + 1
Next
If m = 2 Then
Print j
m = 0
Exit For
Else
m = 0
End If
Next
End Su