how to declare an array of objects for custom c++ class

Question

Hi all

I have declared a custom class header file in my project. I include the header file in my MainPage.Xaml.cpp class and can declare a single object for the class.

But I am unable to create an array of objects for the same.

Kindly help me with the solution.

Thanks.

Header file is :

namespace

metro

{

public

refclassContactInfo

{

//array<Platform::String^>^ cimage;

String^ cimage;

String^ cname;

　

　

public:

　

ContactInfo()

{

cimage=

" ";

cname =

" ";

}

~ContactInfo()

{

cimage=

" ";

cname =

" ";

}

　

voidAddr(Platform::String^ name, Platform::String^ image)

{

cimage = image;

cname = name;

}

};

}

Answer 1

Have you considered a Vector for this purpose? If not, Herb does a great overview of some collections about 31min into this talk.

Writing modern C++ code: how C++ has evolved over the years
TOOL-835T
Speakers: Herb Sutter

The Media Plugins Sample happens to demonstrate the syntax.

void MainPage::scenario3StartVideo_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e) 
{ 
    Scenario3VideoStabilization->RemoveAllEffects(); 
    Scenario4Video->AddVideoEffect("Windows.Media.VideoEffects.VideoStabilization", true, nullptr); 
    auto v = ref new Vector<String^>(); 
    v->Append(".mp4"); 
    v->Append(".wmv"); 
    v->Append(".avi"); 
    PickSingleFileAndSet(v, Scenario3Video);

Does that help?

-David

Answer 2

I am just a beginner in this regard.

Is there no other way to declare a simple array of objects for a custom class?

Answer 3

In C++/CX with a ref class, you need to use the Platform::Array class, or something compatible with ref classes like the STL vector.

Some sample code I've written:

#include <assert.h>
#include <algorithm> 

// Create Array of 10 ints, and one of 2 Strings
Platform::Array<int>^ arr1 = ref new Platform::Array<int>(10);
Platform::Array<Platform::String^>^ arr2 = 
ref new Platform::Array<Platform::String^>(2);

// iterate arr1 using C++ array indexer notation []
for(int i=0; i<arr1->Length; i++)
{
	assert(arr1[i]==0);
	arr1[i]= i+1;
}
 
// iterate arr1 with STL for_each, squaring arr1 values
std::for_each(arr1->begin(), arr1->end(), [](int &element) {
	element = element * element;
});
 
// iterate arr1 values with C++ 'for each'
int val;
for each (int element in arr1) 
{ 
	val = element;
}

// access arr2 values with C++ array indexer notation
arr2[0] = "Zero";
arr2[1] = "One";
arr2[2] = "Two";   // Error: arr2 only has 2 elements 

For your case:

auto arr = ref new Platform::Array<ContactInfo^>(10);

for(int i=0;i<10;i++)

    arr[i] = ref new ContactInfo();

Platform::Array has overloads for the index operator so once you create the array you can use regular array syntax to access elements.

-Steve