protected void btnCalculate_Click(object sender, EventArgs e)
{
DateOfBirth dob = new DateOfBirth();
if (dob.IsValidDate(txtDate.Text.ToString()))
{
lblAge.Text = $"You are a {ddlGender.SelectedValue} and your age is {dob.ShowAge()}";
}
else
{
lblAge.Text = "Please enter valid value";
}
}