VB学习第十一周求取输入两个整数的最大公约数

Public Class Form1
    Sub proc(ByVal a%,ByVal b%,ByRef s%)
        Dim t%,r%
        If a < b Then t = a : a = b : b = t
        r = a Mod b
        do while (r <> 0)
            a = b : b = r : r = a Mod b
        Loop
        s = b
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click
        Dim x%,y%,z%
        x = TextBox1.Text
        y = TextBox2.Text
        Call proc(x,y,z)
        TextBox3.Text &= x & "和" & y & "的最大公约数是" & z & vbCrLf
       
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button2.Click
        End
    End Sub

    Private Sub Form1_Load(sender As Object,e As EventArgs) Handles MyBase.Load

    End Sub
End Class