[Flags]  
        private enum DeliveryOptions  
        {        
            //Make sure you start with zero and increment by powers of 2.          
            //If you don't assign explicit values VS increments by 1.          
            //Very bad. For example (One | Two = Three)  	
            None = 0,  	//(0000)
            Mail = 1,   	//(0001)
            Email = 2,  	//(0010)
            Fax = 4,  //(0100) 	
        }
        
        private DeliveryOptions deliveryFlags;  

        private void button2_Click(object sender, EventArgs e)
        {
            //Put some checkboxes on the form.  
            //A [Flag] enum can hold multiple values at once.  
            //Checking or unchecking boxes adds or removes values.  
            MessageBox.Show(deliveryFlags.ToString());
            MessageBox.Show(Convert.ToInt32(deliveryFlags).ToString()); 
        }

        private bool CheckFlag(DeliveryOptions targetVal, DeliveryOptions checkVal)
        {
            return ((targetVal & checkVal) == checkVal); 
        }
        private bool HasBeenEmailed(DeliveryOptions targetVal)
        {
            return CheckFlag(targetVal, DeliveryOptions.Email); 
        }

        private void btnValueCheck_Click(object sender, EventArgs e)
        {
            bool emailDelivered = HasBeenEmailed(deliveryFlags) ; 
            MessageBox.Show(emailDelivered.ToString()); 
        }

        private void chkOne_CheckedChanged(object sender, EventArgs e)
        {
            if (chkMail.Checked)
            {
                deliveryFlags |= DeliveryOptions.Mail; 
            }
            else
            {
                deliveryFlags &= ~DeliveryOptions.Mail; 
            }
        }

        private void chkTwo_CheckedChanged(object sender, EventArgs e)
        {
            if (chkEmail.Checked)
            {
                deliveryFlags |= DeliveryOptions.Email;
            }
            else
            {
                deliveryFlags &= ~DeliveryOptions.Email;
            }
        }

        private void chkThree_CheckedChanged(object sender, EventArgs e)
        {
            if (chkFax.Checked)
            {
                deliveryFlags |= DeliveryOptions.Fax;
            }
            else
            {
                deliveryFlags &= ~DeliveryOptions.Fax;
            }
        }

[Flags]
  private enum myAttributes
  {
        //Make sure you start with zero and increment by powers of 2.  
        //If you don't assign explicit values VS increments by 1.  
        //Very bad. For example (One | Two = Three)
  	None = 0,
  	One = 1, 
  	Two = 2,
  	Three = 4, 
  	Four = 8
  }

//Put some checkboxes on the form.  

  private void button1_Click_1(object sender, System.EventArgs e)
  {
  	myAttributes displayValue = myAttributes.None; 
  	if(chkOne.Checked)
  	{
    displayValue |= myAttributes.One; 
  	}
  	if(chkTwo.Checked)
  	{
    displayValue |= myAttributes.Two; 
  	}
  	if(chkThree.Checked)

  	{
    displayValue |= myAttributes.Three; 
  	}
  	if(chkFour.Checked)
  	{
    displayValue |= myAttributes.Four; 
  	}
  	MessageBox.Show(displayValue.ToString());  
  }

Note the use of the Bitwise Complement Operator ( ~ ) to AND the negative of the bit you want to set.

Using a Flag Enumeration with Bitwise Operations

C#