CompareValue 浮点数比较

-1 LessThanValue The first value is less than the second value.

0 EqualsValue The two values are equal.

1 GreaterThanValue

var
  A : Single;
  B : Single;
  C : Single;

begin
  A := 23.0;
  B := 23.0;
  C := 23.1;

  // Compare 2 equal floats
  case CompareValue(A, B) of
    LessThanValue    : ShowMessage('A < B');
    EqualsValue      : ShowMessage('A = B');
    GreaterThanValue : ShowMessage('A > B');
  end;

  // Compare 2 unequal floats
  case CompareValue(A, C) of
    LessThanValue    : ShowMessage('A < C');
    EqualsValue      : ShowMessage('A = C');
    GreaterThanValue : ShowMessage('A > C');
  end;

  // Compare 2 unequal floats - but allow for a difference of up to +/- 0.2
  case CompareValue(A, C, 0.2) of
    LessThanValue    : ShowMessage('A < C');
    EqualsValue      : ShowMessage('A = C');
    GreaterThanValue : ShowMessage('A > C');
  end;
end;