Re: Error in calling a function that gets an array of pointers to base class - C / C++ / MFC Discussion Boards

Re: how to initialize a form?

Nelek5-Nov-07 23:28

Nelek

5-Nov-07 23:28

look for OnInitialUpdate

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Help me to understand what I'm saying, and I'll explain it better to you

Wink | ;)

Re: how to initialize a form?

panthal5-Nov-07 23:36

panthal

5-Nov-07 23:36

thank u nelek, just now i found that.

thanks for ur response

panthal

Error in calling a function that gets an array of pointers to base class [modified]

mrobeda5-Nov-07 22:52

mrobeda

5-Nov-07 22:52

Hi,
I need to use a function that uses an array of pointers to a base class, and inside the function handles the pointer according to it's real type (Tha actual type is a derived class).
But i get an error when i call the function :

"Object0124.cpp(1905) : error C2664: 'InsertOutputData' : cannot convert parameter 1 from 'class Array<class Object0124::CDerived *,class Object0124::CDerived *> *' to 'class Array<class Object0124::CBase *,class Object0124::CBase *> &'
A reference that is not to 'const' cannot be bound to a non-lvalue"

I hope that it's clear:
h. file
----------
class CBase
{
int x;
CBase(){x=0;}
};

class CDrived :public base
{
int y;
CString z;
CDrived(){y = 0;z = _T("");}

};
typedef Array<CBase*,CBase *> m_CBaseArray;
typedef Array<CDerived*,CDerived *> m_CderivedArray;
void InsertOutputData(CBaseArray &arrInput,int Mode);

cpp file
---------
void Func()
{
CderivedArray arr;
CDrived var;
var.x = 10;
var.y = 16.533;
var.z = "value"
arr.Add(var)
InsertOutputData(&arr);//or InsertOutputData(arr);//error C2664
}
void InsertOutputData(CBaseArray & arrInput,int mode)
{
for(i = 0;j = 1; j < arrInput.GetSize(),!; j++)
{
if((arrInput.GetAt(i)->x != arrInput.GetAt(j)->x))
{
if(arrInput.GetAt(i)->y == arrInput.GetAt(j)->y)
{
//do something
}
}
}
}

Can anyone tell me what am i doing wrong???

-- modified at 5:22 Tuesday 6th November, 2007

Re: Error in calling a function that gets an array of pointers to base class

Cedric Moonen5-Nov-07 22:59

Cedric Moonen

5-Nov-07 22:59

Your code is unreadable. Check point 5 here[^]

Cédric Moonen
Software developer

Charting control [v1.2]

Re: Error in calling a function that gets an array of pointers to base class

jhwurmbach5-Nov-07 23:50

jhwurmbach

5-Nov-07 23:50

mrobeda wrote:
Can anyone tell me what am i doing wrong???

You treat

typedef Array<CBase*,CBase *> m_CBaseArray;
typedef Array<CDerived*,CDerived *> m_CderivedArray;

as being related types.
They are not. The fact that CDerived is related to CBase does not make the container types releated.
What is related, though, are the dereferenced items of both containers.

What is Array<T>, btw?
A bastardized STL-class?
MFcs CArray, the handicapped step-brother of a STL-class?

Let's think the unthinkable, let's do the undoable, let's prepare to grapple with the ineffable itself, and see if we may not eff it after all.
Douglas Adams, "Dirk Gently's Holistic Detective Agency"

Re: Error in calling a function that gets an array of pointers to base class

mrobeda5-Nov-07 23:58

mrobeda

5-Nov-07 23:58

Array - inherit from MFC's CArray and created my AArray.

So how can i use a generic array that can handle different type of objects?
I need that the fuction will get each time a different type of object in the array.

Re: Error in calling a function that gets an array of pointers to base class

Cedric Moonen6-Nov-07 0:12

Cedric Moonen

6-Nov-07 0:12

mrobeda wrote:
So how can i use a generic array that can handle different type of objects?

You just have to use an array that is declared as an array of pointers to your base class. Then you can fill it with pointers to child classes if you want to (but you need to create the objects dynamically with new, and not forget to delete them afterwards). That's the power of polymorphism Smile | :)

Cédric Moonen
Software developer

Charting control [v1.2]

Re: Error in calling a function that gets an array of pointers to base class

jhwurmbach6-Nov-07 0:33

jhwurmbach

6-Nov-07 0:33

mrobeda wrote:
So how can i use a generic array that can handle different type of objects?

Personally, I would create a pure abstract base class (Interface) for the object-types I would need to put in the container.
You could then either use RTTI/dynamic_cast or a self-devised mechanism of type-determination.

May I ask if you come from a scripting-language background?

Re: Error in calling a function that gets an array of pointers to base class

mrobeda6-Nov-07 2:34

mrobeda

6-Nov-07 2:34

hi,

Thanks for your help, i took Cedric Moonen advise (part of it).

btw - the answear to your question is no.

Browse the file and read it.

CodingLover5-Nov-07 22:44

CodingLover

5-Nov-07 22:44

On my MFC application I read file and do some process on it. Here is the code I used to open and read only.

<br />
CFile srf_ReadFile;<br />
char * srf_FilePath = "ReadFile_001.txt";<br />
if(srf_ReadFile.Open(srf_FilePath, CFile::modeRead))<br />
{<br />
// Do the required process here on ReadFile_001.txt<br />
}<br />

So, the file should be always in the same folder which the project/solution contain. If I want to read another file, say ReadFile_002.txt, have to do it manually, go to the code and gives the new file name.

char * srf_FilePath = "ReadFile_002.txt";

It is too boring. So I want to make it more reliable to use. I want to add a browse button(I think that is the correct word, which is used to find the file in Windows) and set it as the file which I want to read.

How can I do it. Can you guys explain.

I appreciate your help all the time...
Eranga Smile | :)