Call Constructor for object in struct

[David]

Hello,

How do I call the constructor when a class object (non-pointer) is in a
structure?

struct {
...
CMyClass C;
} MyStruct;

MyStruct A, B;

TIA!!

[Victor Bazarov]

Re: Call Constructor for object in struct

David wrote:

How do I call the constructor when a class object (non-pointer) is in a
structure?
>
struct {
...
CMyClass C;
} MyStruct;
>
MyStruct A, B;
>
TIA!!

What do you mean by "call a constructor"? What constructors does
'CMyClass' have? Perhaps this is going to help:

class CMyClass {
public:
CMyClass(int);
CMyClass(char const*);
};

...

MyStruct A = { ..., CMyClass(42) }, B = { ..., CMyClass("David ") };

V
--
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[Juha Nieminen]

Re: Call Constructor for object in struct

David wrote:

Hello,
>
How do I call the constructor when a class object (non-pointer) is in a
structure?
>
struct {
...
CMyClass C;
} MyStruct;
>
MyStruct A, B;

You write a constructor in your struct which calls the constructor of
the member class.

[puzzlecracker]

Re: Call Constructor for object in struct

On Sep 29, 5:04 pm, Juha Nieminen <nos...@thanks. invalidwrote:

David wrote:

Hello,

>

How do I call the constructor when a class object (non-pointer) is in a
structure?

>

struct {
  ...
  CMyClass C;
} MyStruct;

>

MyStruct A, B;

>
  You write a constructor in your struct which calls the constructor of
the member class.

I wonder why C++ is in favor of CMyClass(char const*); copy
constructor then CMyClass(char const &);

Any ideas?

[Victor Bazarov]

Re: Call Constructor for object in struct

puzzlecracker wrote:

[..]
I wonder why C++ is in favor of CMyClass(char const*); copy
constructor then CMyClass(char const &);
>
Any ideas?

Please rephrase your statement about C++ and favors. A copy constructor
for the 'CMyClass' class would be either

CMyClass(CMyCla ss const &);

or

CMyClass(CMyCla ss &);

Anything else is *not* a copy constructor.

V
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[puzzlecracker]

Re: Call Constructor for object in struct

On Sep 29, 5:25 pm, Victor Bazarov <v.Abaza...@com Acast.netwrote:

puzzlecracker wrote:

[..]
I wonder why  C++ is in favor of  CMyClass(char const*); copy
constructor  then      CMyClass(char const &);

>

Any ideas?

>
Please rephrase your statement about C++ and favors.  A copy constructor
for the 'CMyClass' class would be either
>
     CMyClass(CMyCla ss const &);
>
or
>
     CMyClass(CMyCla ss &);
>
Anything else is *not* a copy constructor.
>
V
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No need to rephrase, you answered it. I'm assuming, by providing one
of (pointer or reference version) copy ctors, the other one will not
be generated by compiler by default. Is my assumption correct, aka
reflected in the standard?

[Victor Bazarov]

Re: Call Constructor for object in struct

puzzlecracker wrote:

On Sep 29, 5:25 pm, Victor Bazarov <v.Abaza...@com Acast.netwrote:

>puzzlecracke r wrote:

>>[..]
>>I wonder why C++ is in favor of CMyClass(char const*); copy
>>constructor then CMyClass(char const &);
>>Any ideas?

>Please rephrase your statement about C++ and favors. A copy constructor
>for the 'CMyClass' class would be either
>>
> CMyClass(CMyCla ss const &);
>>
>or
>>
> CMyClass(CMyCla ss &);
>>
>Anything else is *not* a copy constructor.
>>
>V
>--
>Please remove capital 'A's when replying by e-mail
>I do not respond to top-posted replies, please don't ask

>
No need to rephrase, you answered it. I'm assuming, by providing one
of (pointer or reference version) copy ctors, the other one will not
be generated by compiler by default. Is my assumption correct, aka
reflected in the standard?

Erm... There is *no* "pointer version copy ctor". Copy constructors
*always* take a reference argument. And, no, if you define some other
constructor, the compiler will still provide a copy constructor in the
former interface, if it can (depends whether the members are copyable).

V
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[James Kanze]

Re: Call Constructor for object in struct

On Sep 29, 10:47 pm, Victor Bazarov <v.Abaza...@com Acast.netwrote:

David wrote:

How do I call the constructor when a class object
(non-pointer) is in a structure?

struct {
...
CMyClass C;
} MyStruct;

MyStruct A, B;

What do you mean by "call a constructor"?

According to the standard, you can't "call a constructor:-)".
At any rate, what he probably wants is to initialize the
elements.

What constructors does 'CMyClass' have? Perhaps this is going
to help:

class CMyClass {
public:
CMyClass(int);
CMyClass(char const*);
};

...

MyStruct A = { ..., CMyClass(42) }, B = { ..., CMyClass("David ")};

Note that in this case, you don't even need the CMyClass. If
the constructors take a single argument, and aren't declared
explicit, explicit conversion will take place.

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

[James Kanze]

Re: Call Constructor for object in struct

On Sep 29, 11:25 pm, Victor Bazarov <v.Abaza...@com Acast.netwrote:

[...]

Please rephrase your statement about C++ and favors. A copy constructor
for the 'CMyClass' class would be either

CMyClass(CMyCla ss const &);

or

CMyClass(CMyCla ss &);

Anything else is *not* a copy constructor.

MyClass( MyClass volatile& ) ;
MyClass( MyClass const volatile& ) ;

:-).

(Of course, I've never found a use for volatile except on very
basic types, and it doesn't work with most modern compilers
anyway. But formally...)

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

[David]

Re: Call Constructor for object in struct

Yeah, basically that... Would this work:

struct {
int a,b,c,d,e,f,g,h ,i,j;
CMyClass C;
} MyStruct;

MyStruct A={CMyClass(wha tever))};

or would I have to always deal with a through j?

How about:

struct {
int a,b,c,d,e,f,g,h ,i,j;
CMyClass C;

void Init(void) {
a=b=c=d=e=f=g=h =i=j=0;
C(whatever)
}
} MyStruct;

MyStruct A;

A.Init();

??

"Victor Bazarov" <v.Abazarov@com Acast.netwrote in message
news:gbres6$r8v $3@news.datemas .de...

David wrote:

>How do I call the constructor when a class object (non-pointer) is in a
>structure?
>>
>struct {
> ...
> CMyClass C;
>} MyStruct;
>>
>MyStruct A, B;
>>
>TIA!!

>
What do you mean by "call a constructor"? What constructors does
'CMyClass' have? Perhaps this is going to help:
>
class CMyClass {
public:
CMyClass(int);
CMyClass(char const*);
};
>
...
>
MyStruct A = { ..., CMyClass(42) }, B = { ..., CMyClass("David ") };
>
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
>