Problems with constructors in nested structs and unions

[Gutzy]

I have a struct nested within a class and a union of that struct. If I have a struct constructor that takes arguments, then the union won't compile.

I also want to create an instance of the struct using an argument. That line also fails.
Also if I try to create an instance using braces to initialise it fails.

class test
{
public:
test(void);
~test(void);

struct dtType {
// inline constructors with initialisation lists
dtType() : mins(0), hrs(0),day(0),mnth(0),year(0),DPOffset(0),DTType(0) {}
dtType(byte z) : mins(z), hrs(z),day(z),mnth(z),year(z),DPOffset(0),DTType(0) {}
dtType(byte n,byte h, byte d, byte m, byte y, byte o, byte t) : mins(n), hrs(h),day(d),mnth(m),year(y),DPOffset(o),DTType(t) {}

// overloaded operator functions
bool operator< (dtType date){return true;};
bool operator<= (dtType date){return true;};
bool operator> (dtType date){return true;};
bool operator>= (dtType date){return true;};
bool operator== (dtType date){return true;};

// data members
unsigned mins: 3;
unsigned hrs: 5; // 8 bits
unsigned day: 5;
unsigned mnth: 4;
unsigned year: 7; // 16 bits
unsigned DPOffset: 6;
unsigned DTType : 2;
};

// if I comment out the union it compiles, otherwise I get:
// error C2620: member 'test::dtUnion::dt' of union 'test::dtUnion' has user-defined constructor or non-trivial default constructor

union dtUnion {
dtType dt;
unsigned long dtLong; // 32 bits
} dtU;


dtType judgement_day; // compiles OK

dtType judgement_day2(1); // error C2059: syntax error : 'constant'

dtType judgement_day3 = {1,1,1,1,1,0,0}; // error C2334: unexpected token(s) preceding '{'; skipping apparent function body

};

[D_Drmmr]

Please use code tags when posting code to preserve the indentation.
[QUOTE=Gutzy;2076963]

class test
{
    //...
    dtType judgement_day; // compiles OK

    dtType judgement_day2(1); // error C2059: syntax error : 'constant'

    dtType judgement_day3 = {1,1,1,1,1,0,0}; // error C2334: unexpected token(s) preceding '{'; skipping apparent function body
};

You have listed the 'judgement_day' things as members of your class. Therefore, judgement_day2 is interpreted as a member function of class test. If you want to have judgement_day2 as a member variable of class test, then you should define it similar to judgement_day, and initialize it in the constructor of test.

[Igor Vartanov]

I have a struct nested within a class and a union of that struct. If I have a struct constructor that takes arguments, then the union won't compile.

// if I comment out the union it compiles, otherwise I get:
// error C2620: member 'test::dtUnion::dt' of union 'test::dtUnion' has user-defined constructor or non-trivial default constructor

union dtUnion {
dtType dt;
unsigned long dtLong; // 32 bits
} dtU;

Compiler Error C2620 article says:

A union member cannot have a default constructor.

[Gutzy]

Thanks for your help. I'll get rid of the union and use a cast. Can you help me on how to get the compiler to let me cast my struct to a long?

[Ejaz]

Thanks for your help. I'll get rid of the union and use a cast. Can you help me on how to get the compiler to let me cast my struct to a long?

Look into MSDN for reference and example.

[D_Drmmr]

Thanks for your help. I'll get rid of the union and use a cast. Can you help me on how to get the compiler to let me cast my struct to a long?

You can use a POD struct to keep the data and store an instance of that struct in your class that you want to cast.
Something like this (not tested):

struct dtType
{
    // c'tors and operators

    unsigned long ToLong() const {
        union {
            data d;
            unsigned long l;
        } u;
        u.d = m_Data;
        return u.l;
    }
private:
    struct data {
        unsigned mins: 3;
        unsigned hrs: 5; // 8 bits
        unsigned day: 5;
        unsigned mnth: 4;
        unsigned year: 7; // 16 bits
        unsigned DPOffset: 6;
        unsigned DTType : 2;
    } m_Data;
};