validation in c#

Blank validation on textbox Method-1 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace Validation_on_textbox { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { if (textBox1.Text == "") { MessageBox.Show("Name Field cannnot be blank"); textBox1.Focus(); } else { MessageBox.Show("Correct"); } clear(); } private void clear() { textBox1.Text = ""; } } } Method-2 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace Validation_on_textbox { public partial class Form2 : Form { public Form2() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { foreach (Control c1 in this.Controls) { if (c1 is TextBox) { if (c1.Text == "") { MessageBox.Show("Name Field cannnot be blank"); c1.BackColor = Color.Orange; textBox1.Focus(); } else { MessageBox.Show("Correct"); c1.BackColor = Color.White; } } } clear(); } private void clear() { textBox1.Text = ""; } } } Method-3 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace Validation_on_textbox { public partial class Form3 : Form { public Form3() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { if (textBox1.Text.Trim() == "") { errorProvider1.SetError(textBox1, "Name Field cannnot be blank"); textBox1.Focus(); } else { errorProvider1.Clear(); MessageBox.Show("Correct"); } clear(); } private void clear() { textBox1.Text = ""; } } }