QDoubleSpinBox and QDoubleValidator

Currently I am using QDoubleSpinBox in my coding, but before that i were using QAbstractSpinBox and make use of QDoubleValidator with 2 decimal positions and works fine.

Now while editing into the QDoubleSpinBox, the string obtained from QDoubleSpinbox [in exponential form] is always returning 3 decimal positions and QDoubleValidator is always giving and "Invalid" result.

Is the QDoubleValidator necessary for QDoubleSpinBox.?

No, you don't need the validator for QDoubleSpinBox.