symmetric difference

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The symmetric difference operator is applicable to set variables. By mathematical definition, A >< B is [math]\displaystyle{ \left( A \setminus B \right) \cup \left( B \setminus A \right) }[/math].

procedure test_differ;
var
  a: set of char = ['a', 'b', 'c'];
  b: set of char = ['b', 'c', 'x', 'y'];
  c: set of char;
begin
  c:= a >< b; // c becomes ['a', 'x', 'y']
end;

The symmetric difference operator is defined by Extended Pascal, ISO standard 10206. In the FPC it is available in any mode, not just {$mode extendedPascal}.