Validate a Textbox in ASP .NET without Validation Controls

private void textBox1_KeyPress(object sender, KeyPressEventArgs e) {         e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar); }

if (!System.Text.RegularExpressions.Regex.IsMatch(textbox.Text, "^[0-9]*$"))

Only letters:

Regex.IsMatch(input, @"^[a-zA-Z]+$");

Use the expression:

^[a-zA-Z0-9]*$

ie:

Regex r = new Regex("^[a-zA-Z0-9]*$"); if (r.IsMatch(SomeString)) { ... }

//Only numeric

private void txtHomePhone_KeyPress(object sender, KeyPressEventArgs e)

{

if (e.KeyChar >= '0' && e.KeyChar <= '9' || e.KeyChar == '') //The character represents a backspace

{

e.Handled = false; //Do not reject the input

}

else

{

e.Handled = true; //Reject the input

}

}

//TextBox only accept alphabetic characters

private void textBox1_TextChanged(object sender, EventArgs e)

{

if (!System.Text.RegularExpressions.Regex.IsMatch(textBox1.Text, "^[a-zA-Z]"))

{

MessageBox.Show("This textbox accepts only alphabetical characters");

textBox1.Text.Remove(textBox1.Text.Length - 1);

}

}