You can create method given below for all similar kind of controls. You can call this method by passing array of control i.e in your case you can call like given below (pass all textboxs which has to validated)
TextBox[] listTextBox = {textBox1,textBox2};
public bool CheckTextBoxNull(TextBox[] listTextBox)
{
for (int i = 0; i <= listTextBox.Length - 1; i++)
{
if (listTextBox[i].Text.Trim().Length == 0)
{
listTextBox[i].BackColor = System.Drawing.Color.FromArgb(255, 192, 192);
listTextBox[i].Focus();
return false;
}
}
return true;
}