0
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 = "";
}
}
}

0
Dear Ravindra,
Please consider to decorate the question properly so that one can understand your problems/requirements properly. I also encourage to do some Googling before you share your problems. We're to help, not to do your homework.
Below is the link where you can grab a lot of them:
Validation in C#Hope this helps !
Thanks,
Sunny K