***有25個素數。
Public?Class?Form1
Dim?n?As?Int16?=?0
Private?Sub?Button2_Click(ByVal?sender?As?System.Object,?ByVal?e?As?System.EventArgs)?Handles?Button2.Click
TextBox1.Text?=?PrimeNumber(2,?100)
MsgBox("***有素數："?&?n?&?"個。")
End?Sub
Function?PrimeNumber(ByVal?startNum?As?Long,?ByVal?endNum?As?Long)?As?String
Dim?str?As?String?=?""
Dim?i?As?Long
Dim?j?As?Long
Dim?yn?As?Boolean?=?True
For?j?=?startNum?To?endNum
For?i?=?2?To?Int(Math.Sqrt(j))
If?j?Mod?i?=?0?Then?GoTo?nxt
Next
n?+=?1
If?n?Mod?5?=?0?Then
str?=?str?&?j?&?vbCrLf
Else
str?=?str?&?j?&?","
End?If
nxt:
Next
Return?str
End?Function
End?Class