Public Class Form1
{
    TextBox tbx = new TextBox[5];
    int arr = {1, 2, 3, 4, 5};
//=======================================================================
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click <<< Event onclick ของ button1
   {
        for (int i = 0; i<arr.Length; i++)
            tbx[i+1].Text = arr[i].ToString();
   }
//=======================================================================
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load <<< Event PageLoad
   {
        SetArr();
   }
//=======================================================================
    private void  SetArr()
   {
        tbx[1] = TextBox1;
        tbx[2] = TextBox2;
        tbx[3] = TextBox3;
        tbx[4] = TextBox4;
   }
}
//=======================================================================

มาจาก http://www.narisa.com/forums/index.php?showtopic=29161