c++ - How can I initialize the default value of a CArray<CClass*> function parameter with an empty CArray? -

i know better std::vector, application messing with, has bunch of carray parameters on lot of related functions ... , not change them @ moment!

i want define empty carray<cclass*> — array of pointers cclass, problem can not be on cclass constructor — default value of function parameter.

approach 1

if try assignment operator , default constructor:

void function(carray<cclass*> parameter = carray<cclass*>()); 

i error:

1>c:\program files (x86)\microsoft visual studio 10.0\vc\atlmfc\include\afxtempl.h(262): error c2248: 'cobject::cobject' : cannot access private member declared in class 'cobject' 1>          c:\program files (x86)\microsoft visual studio 10.0\vc\atlmfc\include\afx.h(535) : see declaration of 'cobject::cobject' 1>          c:\program files (x86)\microsoft visual studio 10.0\vc\atlmfc\include\afx.h(510) : see declaration of 'cobject' 1>          diagnostic occurred in compiler generated function 'carray<type>::carray(const carray<type> &)' 1>          1>          [ 1>              type=cclass * 1>          ] 

approach 2

i tried copy constructor:

void function(carray<class*> parameter(carray<cclass*>())); 

i got errors:

 >file.cpp(line x): error c2664: 'functionclass::function' : cannot convert parameter 1 'carray<type>' 'carray<type> (__cdecl *)(carray<type> (__cdecl *)(void))' 1>          1>          [ 1>              type=cclass* 1>          ] 1>          no user-defined-conversion operator available can perform conversion, or operator cannot called 

• line x: contains call supplying parameter function, shown: pfunctionclass->function(parameter);

1>cfunctionclass.cpp(line y): error c2511: 'void cfunctionclass::function(carray)' : overloaded member function not found in 'cshoeplacedoc' 1> 1> [ 1> type=cclass* 1> ] 1> functionclass.h(line a) : see declaration of 'cfunctionclass'

• line y contains function implementation header, shown: `void cfunctionclass::function(carray parameter)

1>file.cpp(line z): error c2660: 'cclassfunction::function' : function not take 0 arguments

• line z: contains call functionwithout supplying parameters, shown: pclassfunction->function();

the approach didn't work, got way towards conclusion: not possible use copy-constructor assigning default value function parameter.

approach 3

and if try lambda:

void function(carray<cclass*> parameter = [] () -> carray<cclass*>{ return carray<cclass*> (); } ); 

, multiple outputs of these 2 errors:

1>functionclass.h(line a): error c2440: 'default argument' : cannot convert '`anonymous-namespace'::<lambda2>' 'carray<type>' 1>          1>          [ 1>              type=cclass* 1>          ] 1>          no user-defined-conversion operator available can perform conversion, or operator cannot called 1>functionclass.h(line b): fatal error c1903: unable recover previous error(s); stopping compilation 

• line a: method declaration
• line b: closing } of functionclass class contains function method

origin of problem

the root cause of problem seems fact carray class directly derived cobject, declares assignment operator private:

class afx_novtable cobject { //... private:     cobject(const cobject& objectsrc);              // no implementation     void operator=(const cobject& objectsrc);       // no implementation //... } 

so, how can supply empty array default value parameter?

with declaration

void function(carray<cclass*> parameter /*...*/); 

you can't. calling function invoke private copy constructor of cobject have noticed.

what do, add object of static carray<cclass*> in class , initialize function reference it. way empty (as long not populate it...) , can perform .isempty() check on it.

private:     static carray<cclass*> myobj; //... void function(carray<cclass*> &parameter = myobj); 

or initialize 0. way check if (parameter) or if (null == parameter).

void function(carray<cclass*> *parameter = null);