Retrieving data elements from inside an ArrayList Class

[shiftingspanner]

I've created a class PulldownArray, which contains two strings Value and Description. I created an array of this class called PulldownTABLE with the ArrayList^ command in my main program and I then populate it with the .Add method. All this works fine.

How do I retrive the Value and Description strings for an individual item in PulldownTABLE?

public ref class PulldownArray{
	public:
		String^ myValue;
		String^ myDescription;
	public:
		~PulldownArray(){
		}
		PulldownArray( String^ strValue, String^ strDescription ){
			this->myValue = strValue;
			this->myDescription = strValue + " \t " + strDescription;
		}
	property
		String^ Value{
			String^ get(){
			return myValue;
			}
		}
	property
		String^ Description{
			String^ get(){
				return myDescription;
			}
	   }
	virtual 
		String^ ToString() override{
		   return this->myValue;
	    }
};


main{.....

String^ ReturnString;

ArrayList^ PulldownTABLE = gcnew ArrayList;
PulldownTABLE->Add(gcnew PulldownArray("TABLE1", "TABLE1_description"));
PulldownTABLE->Add(gcnew PulldownArray("TABLE2", "TABLE2_description"));

//Works, but I don't want to have to write overrides for every element
ReturnString = PulldownTABLE[1]->ToString();
//Can see both myDescription and Description in the debugger but these both fail at compile
ReturnString = PulldownTABLE[1]->myDescription;
ReturnString = PulldownTABLE[1]->Description();
...
}

Any help would be appreciated but please keep it simple as I'm particularily stupid and ignorant.

[jonsca]

Because of how the ArrayList stores objects (as objects of type Object ^) you need to cast your ArrayList member before it will give up it's public properties and methods.

ReturnString = (static_cast<PulldownArray^>(PulldownTABLE[0]))->Description;
	
//Consider the List instead, no need to cast
List<PulldownArray^> ^ pdtl = gcnew List<PulldownArray^>();
String ^ returnstring2 = pdtl[1]->Description;

The List is in System::Collections::Generic but if you are using an older .NET you may be stuck with ArrayList

[shiftingspanner]

Hi Jonsca (love your title!). Thank you muchly for the tip on the casting of the ArrayList member. I definitely give that a try.

I'm using Visual C++ 2008 so I probably do have access to the List. BUT I'm currently teaching myself C++ so it's going to take me a couple of days to assimulate what you've suggested here. It certainly looks a whole lot neater, cleaner and whole heap more elegant so I'm interested....

Thanks once again.

[jonsca]

Thanks!

Yeah,ArrayList was a .NET 2.0 thing. I've never dissected them but I believe the List is better designed behind the scenes. I don't know if there's any speed improvement.

Take your time with it. The C++ that comes with the CLR bits is different from standard C++. All the ref classes, handles (^), etc. are particular to the C++/CLI dialect. Just something to bear in mind while you are learning this. If you decide to branch into C# eventually you'll find this to be a hair closer to C# than standard c++ (in that C# and C++/CLI both use the .NET libraries). Just my 0.02.