<һ>ʹDo WhileLoop
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
     Dim m,n As Integer, s As Long
s = 0: n = 0
m =Val( TextBox1.Text)
Do While n <= m
s = s + n
n = n + 1
Loop
Label2.Text = "1+2+3+...+" & m & "=" & s
End Sub
<>ʹDoLoop until 
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
     Dim m,n As Integer, s As Long
s = 0: n = 0
m =Val( TextBox1.Text)
Do
s = s + n
n = n + 1
Loop Until n > m
Label2.Text = "1+2+3+...+" & m & "=" & s
End Sub 
<>ʹForNext
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
     Dim m,n As Integer, s As Long
s = 0: n = 0
m =Val( TextBox1.Text)
Do
If n > m Then
Exit Do
End If
s = s + n
n = n + 1
Loop
Label2.Text = "1+2+3+...+" & m & "=" & s
End Sub
