Re: Convert Objects from an Arraylists to Double?

From:

"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 5 Feb 2008 08:31:59 -0600

Message-ID:

<OrBfHOAaIHA.484@TK2MSFTNGP06.phx.gbl>

/KC wrote:

Hi! Ben

I've looked closely at what you've written and tried to do what
you've said but I end up with more error messages. I'm kind of new to
this managed C++ approach as you might have guessed. I have some
experience with VS 6.0 and have now started with VS2008. I can tell
you that It's been a bit of a cultural chock for me :-)

Here is the how the code look now:

////////////////////////////////////////////////////////////////////////////////////////////
using namespace System::Collections::Generic;
...
...
...

if(COpenFile::get_stmReader())
{
//!! EN ARRAYLIST MED R?TT ENTITETER !!
ArrayList^ lstTest = pForm1.get_LineX_StartValueArray();

//!! EN DOUBLE ARRAY MED R?TT STORLEK !!
array<double>^ dblArray = gcnew array<double>(
(int)CConvert::get_NumberOfItems() );

List<System::Double> ^ List1 = pForm1.get_LineX_StartValueArray();
List<System::Double> ^ List2 = pForm1.get_LineY_StartValueArray();
List<System::Double> ^ List3 = pForm1.get_LineX_EndValueArray();
List<System::Double> ^ List4 = pForm1.get_LineY_EndValueArray();

for( int i = 0; i < List1->Count; ++i )
{
g->DrawLine( System::Drawing::Pens::Red, List1[ i ], List2[ i ],
List3[ i ], List4[ i ]);
}
}

////////////////////////////////////////////////////////////////////////////////////////////
Error message;
////////////////////////////////////////////////////////////////////////////////////////////

\DrawLine.cpp(38) : error C2440: 'initializing' : cannot convert from
'System::Collections::ArrayList ^' to
'System::Collections::Generic::List<T> ^'
1> with
1> [
1> T=double
1> ]
1> No user-defined-conversion operator available, or
1> Types pointed to are unrelated; conversion requires
reinterpret_cast, C-style cast or function-style cast
1>.\DrawLine.cpp(39) : error C2440: 'initializing' : cannot convert
from 'System::Collections::ArrayList ^' to
'System::Collections::Generic::List<T> ^'
1> with
1> [
1> T=double
1> ]
1> No user-defined-conversion operator available, or
1> Types pointed to are unrelated; conversion requires
reinterpret_cast, C-style cast or function-style cast
////////////////////////////////////////////////////////////////////////////////////////////

Maybe it's obvious to you when you see the error message above. I
must admit that I've come to a point where I've started to look at
alternative solutions, I'm sorry to say. Time is running out for
ArrayList.

Now you have a much more reasonable error message. Change ArrayList to
System::Collection::Generic::List<System::Double> everywhere and things will
work.

ArrayList is dead. It was a .NET 1.1 workaround for the lack of generics,
now we have generics and no more need for ArrayList.

Regard
KC