Software Applications Programming Errors and solutions.

Change textbox color if textbox is empty in asp.net using c# private void button1_Click(object sender, EventArgs e) { textBox1.BackColor = Color.White; textBox2.BackColor = Color.White; textBox3.BackColor = Color.White; textBox4.BackColor = Color.White; string[] text = new string[4]; text[0] = System.Convert.ToString(textBox1.Text); text[1] = System.Convert.ToString(textBox2.Text); text[2] = System.Convert.ToString(textBox3.Text); text[3] = System.Convert.ToString(textBox4.Text); for (int i = 0; i <= 3; i++) { if (text == "") { errorshow(i); } } } private void errorshow(int k) { switch (k) { case 0: textBox1.BackColor = Color.Red; break; case 1: textBox2.BackColor = Color.Red; break; case 2: textBox3.BackColor = Color.Red; break; case 3: textBox4.BackColor = Color.Red; break; } }