And

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Boolean operation

And produces a value of true if and only if both of its operands are true.

Truth table

A B   A and B  
  false     false     false
  false   true   false
  true   false   false
  true   true   true


Bitwise operation

Bitwise and sets a bit to 1 if and only if all of the corresponding bits in its operands are 1.

Is power of two

<delphi> function IsPowerOfTwo( const aValue : longint ): boolean; var

 x : longint;
 b : boolean;

begin

 b := false;
 if aValue <> 0 then
   begin
     x := aValue - 1;
     x := x and aValue;
     if x = 0 then b := true;
   end;
 result := b;

end; </delphi>

If you call IsPowerOfTwo(4) then get true. If you call IsPowerOfTwo(5) then get false .

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