This class implements function which can be used in ICalculator to calculate decreased by 1 value of specified argument(if only one argument is specified) or decreased by second argument value.

You can find more information in comments below. Overrided methods can be found in corresponding base class or interface.

class CProcedureDec :public CProcedure
    {
    public:
        CVariable *Calculate(CVariable *parent, CVariable *args) override;
    
        CProcedureDec();
    };