C++ Operator overload issue

Question

In a class I have the following enum ad Operator overloads, as show in How to use enums as flags in C++?.

enum OperationMode
{
//...
};

OperationMode operator | (OperationMode lhs, OperationMode rhs )
{
    // Cast to int first otherwise we'll just end up recursing
    return static_cast< OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}

OperationMode operator + (OperationMode lhs, OperationMode rhs )
{
    // Cast to int first otherwise we'll just end up recursing
    return static_cast< OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}

the compiler return the followinf errors:

../MngSpiLS7633R/MngSpiLS7633R.h:40:84: error: 'MngSpiLS7633R::OperationMode MngSpiLS7633R::operator|(MngSpiLS7633R::OperationMode, MngSpiLS7633R::OperationMode)' must take exactly one argument
inline OperationMode operator | (const OperationMode lhs, const OperationMode rhs )
                                                                                ^
../MngSpiLS7633R/MngSpiLS7633R.h:46:72: error:    'MngSpiLS7633R::OperationMode MngSpiLS7633R::operator+(MngSpiLS7633R::OperationMode, MngSpiLS7633R::OperationMode)' must take either zero or one argument
inline OperationMode operator + (OperationMode lhs, OperationMode rhs )

Why the overload isn't correct?

Additional Informations, after some comments/Answer: First, Thanks for the comments and answer.

The operator is member of a class, where the enum is defined. I'm new in c++ and oop.... can anyone suggest an example of code for an operator meber of a class?

Here there is the complete class code, im trying to set operator + and | for using the single values of the enums as bitmask for the parameters of void initialize(OperationMode MDR0_OperationMode, AddOperationMode MDR1_AddOperationMode) function.

class MngSpiLS7633R
{
public:

enum OperationMode
{
    Om_Quad_None = 0x00,
    Om_Quad_x1  = 0x01,
    Om_Quad_x2 = 0x02,
    Om_Quad_x4 = 0x03,

    Om_Count_freeRun     = 0x00,
    Om_Count_SingleCycle = 0x04,
    Om_Count_RangeLimit = 0x08,
    Om_Count_ModuloN    = 0x0C,

    Om_Index_disabled = 0x00,
    Om_Index_loadCNTR = 0x10,
    Om_Index_resetCNTR = 0x20,
    Om_Index_loadOTR    = 0x30,

    Om_AsynIndex_async = 0x00,
    Om_AsynIndex_sync = 0x40,

    Om_ClockFilter_1x = 0x00,
    Om_ClockFilter_2x = 0x80
};

OperationMode operator | (OperationMode lhs, OperationMode rhs )
{
    // Cast to int first otherwise we'll just end up recursing
    return static_cast< OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}

OperationMode operator + (OperationMode lhs, OperationMode rhs )
{
    // Cast to int first otherwise we'll just end up recursing
    return static_cast< OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}


enum AddOperationMode
{
    Aom_CouterMode_4byte = 0x00,
    Aom_CouterMode_3byte = 0x01,
    Aom_CouterMode_2byte = 0x02,
    Aom_CouterMode_1byte = 0x03,

    Aom_Counting_Enabled  = 0x00,
    Aom_Counting_Disabled = 0x04,

    //bit-3 not used = 0x08
    Aom_b4flag_Nop = 0x00,
    Aom_b4flag_onIDX = 0x10,

    Aom_b5flag_Nop = 0x00,
    Aom_b5flag_onCMP = 0x20,

    Aom_b6flag_Nop = 0x00,
    Aom_b6flag_onBW = 0x40,

    b7flag_Nop = 0x00,
    b7flag_onCY = 0x80,

};

AddOperationMode operator | ( AddOperationMode lhs, AddOperationMode rhs )
{
    // Cast to unsigned char first otherwise we'll just end up recursing
    return static_cast< AddOperationMode >( static_cast< unsigned char >( lhs ) | static_cast< unsigned char >( rhs ) );
}

AddOperationMode operator + ( AddOperationMode lhs, AddOperationMode rhs )
{
    // Cast to unsigned char first otherwise we'll just end up recursing
    return static_cast< AddOperationMode >( static_cast< unsigned char >( lhs ) | static_cast< unsigned char >( rhs ) );
}



MngSpiLS7633R(int SSPin);
MngSpiLS7633R(int SSPin, bool ExternalNot);
virtual ~MngSpiLS7633R();
void initialize(OperationMode MDR0_OperationMode, AddOperationMode MDR1_AddOperationMode);
void resetCounter();
long get();
void set(long initValue);


private:
static const char SpiBitOrder = MSBFIRST;
static const char SpiMode = SPI_MODE0;
static const long SpiClock = 4000000; //4 Mhz maximum ratings

int SSEnabledLevel;
int SSDisabledLevel;
int SSPin;
bool SSExternalNot;

};

Is `operator |` member of a class? If yes, then it needs to take only one argument, i.e. its right hand side. — vsoftco, Jan 25 '17 at 15:27
Work as expected [here](http://coliru.stacked-crooked.com/a/4f2cedffa7c1e88d). — Jarod42, Jan 25 '17 at 15:32
Except if `MngSpiLS7633R` is a namespace (which I doubt), comment from vsoftco is the answer. — YSC, Jan 25 '17 at 15:51
in this case operator is member of the class where the enum is defined. — EffegiWeb, Jan 26 '17 at 08:45

score 0 · Answer 1 · answered Jan 25 '17 at 15:53

From the error message

error: 'MngSpiLS7633R::OperationMode MngSpiLS7633R::operator|...

MngSpiLS7633R is either a namespace or a class name whom operator| is a member of. If this is the case, the operator must only take one argument or be defined as a free function (outside the class MngSpiLS7633R).

score 0 · Answer 2 · answered Jan 30 '17 at 08:46

I've resolved the problem using friend modifier for the operator declaration inside the class.

friend AddOperationMode operator | ( AddOperationMode lhs, AddOperationMode rhs );

friend AddOperationMode operator + ( AddOperationMode lhs, AddOperationMode rhs );

Then the operator are defined outside the class:

MngSpiLS7366R::OperationMode operator | (MngSpiLS7366R::OperationMode lhs, MngSpiLS7366R::OperationMode rhs )
{
// Cast to int first otherwise we'll just end up recursing
return static_cast< MngSpiLS7366R::OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}

MngSpiLS7366R::OperationMode operator + (MngSpiLS7366R::OperationMode lhs, MngSpiLS7366R::OperationMode rhs )
{
// Cast to int first otherwise we'll just end up recursing
return static_cast< MngSpiLS7366R::OperationMode >( static_cast< int >( lhs ) | static_cast< int >( rhs ) );
}

C++ Operator overload issue

2 Answers2