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Using a Flag Enumeration with Bitwise Operations

/ Published in: C#
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Note the use of the Bitwise Complement Operator ( ~ ) to AND the negative of the bit you want to set.

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  1. [Flags]  
  2.         private enum DeliveryOptions  
  3.         {        
  4.             //Make sure you start with zero and increment by powers of 2.          
  5.             //If you don't assign explicit values VS increments by 1.          
  6.             //Very bad. For example (One | Two = Three)  	
  7.             None = 0,  	//(0000)
  8.             Mail = 1,   	//(0001)
  9.             Email = 2,  	//(0010)
  10.             Fax = 4,  //(0100) 	
  11.         }
  12.  
  13.         private DeliveryOptions deliveryFlags;  
  14.  
  15.         private void button2_Click(object sender, EventArgs e)
  16.         {
  17.             //Put some checkboxes on the form.  
  18.             //A [Flag] enum can hold multiple values at once.  
  19.             //Checking or unchecking boxes adds or removes values.  
  20.             MessageBox.Show(deliveryFlags.ToString());
  21.             MessageBox.Show(Convert.ToInt32(deliveryFlags).ToString()); 
  22.         }
  23.  
  24.         private bool CheckFlag(DeliveryOptions targetVal, DeliveryOptions checkVal)
  25.         {
  26.             return ((targetVal & checkVal) == checkVal); 
  27.         }
  28.         private bool HasBeenEmailed(DeliveryOptions targetVal)
  29.         {
  30.             return CheckFlag(targetVal, DeliveryOptions.Email); 
  31.         }
  32.  
  33.         private void btnValueCheck_Click(object sender, EventArgs e)
  34.         {
  35.             bool emailDelivered = HasBeenEmailed(deliveryFlags) ; 
  36.             MessageBox.Show(emailDelivered.ToString()); 
  37.         }
  38.  
  39.         private void chkOne_CheckedChanged(object sender, EventArgs e)
  40.         {
  41.             if (chkMail.Checked)
  42.             {
  43.                 deliveryFlags |= DeliveryOptions.Mail; 
  44.             }
  45.             else
  46.             {
  47.                 deliveryFlags &= ~DeliveryOptions.Mail; 
  48.             }
  49.         }
  50.  
  51.         private void chkTwo_CheckedChanged(object sender, EventArgs e)
  52.         {
  53.             if (chkEmail.Checked)
  54.             {
  55.                 deliveryFlags |= DeliveryOptions.Email;
  56.             }
  57.             else
  58.             {
  59.                 deliveryFlags &= ~DeliveryOptions.Email;
  60.             }
  61.         }
  62.  
  63.         private void chkThree_CheckedChanged(object sender, EventArgs e)
  64.         {
  65.             if (chkFax.Checked)
  66.             {
  67.                 deliveryFlags |= DeliveryOptions.Fax;
  68.             }
  69.             else
  70.             {
  71.                 deliveryFlags &= ~DeliveryOptions.Fax;
  72.             }
  73.         }

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