waitingForOperand is true when the calculator is expecting the user to start typing an operand.Īdditive and multiplicative operators are treated differently because they have different precedences.pendingMultiplicativeOperator stores the last multiplicative operator clicked by the user.pendingAdditiveOperator stores the last additive operator clicked by the user.factorSoFar stores a temporary value when doing multiplications and divisions.When the user clicks =, sumSoFar is recomputed and shown on the display.
sumSoFar stores the value accumulated so far.sumInMemory contains the value stored in the calculator's memory (using MS, M+, or MC).These variables, together with the contents of the calculator display (a QLineEdit), encode the state of the calculator: The categories are digits, unary operators ( Sqrt, x², 1/x), additive operators ( +, -), and multiplicative operators ( ×, ÷). For these, we connect multiple buttons to the same slot (e.g., digitClicked()). For example, all the digit buttons (labeled 0 to 9) append a digit to the current operand. QObject::eventFilter() is reimplemented to handle mouse events on the calculator's display.īuttons are grouped in categories according to their behavior. It inherits from QDialog and has several private slots associated with the calculator's buttons. The Calculator class provides a simple calculator widget.
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