找出數值是否為質數-IsUnDivNum:
最近常收到一些來信,都是詢問有關檢查質的問題,因此站長在此開了一個新的單元,我們可以自己寫一個函數來判斷一個數值是否為質數:Private Function IsUnDivNum(ByVal Number As Integer) As Byte
'1 = 是質數
'2 = 不是質數
'3 = 輸入錯誤
Dim lDiv As Integer
Dim rDiv As Integer
If Number <= 1 Then
IsUnDivNum = 3
Exit Function
End If
If Number = 2 Then IsUnDivNum = 1
Number = Fix(Number)
For lDiv = 2 To Number - 1
If Number Mod lDiv = 0 Then
IsUnDivNum = 2
Exit Function
End If
Next lDiv
IsUnDivNum = 1
End Function
Private Sub Command1_Click()
'用法範例:
On Error GoTo ERH
任意一個數 = InputBox("請入一個數目", "檢查質數")
Select Case IsUnDivNum(任意一個數)
Case 1
MsgBox "是質數"
Case 2
MsgBox "不是質數"
Case 3
MsgBox "輸入錯誤"
End Select
Exit Sub
ERH:
MsgBox "輸入錯誤"
End Sub
範例可到VB範例單元下載