Borland C++ ListView Error - c++

Question

I keep getting the error:
[BCC32 Error] DogReport.cpp(29): E2288 Pointer to structure required on left side of -> or ->*
when trying to compile.
I am trying to populate a TListView with elements from my TList made up of structs.
void __fastcall TDogReportForm::FormCreate(TObject *Sender)
{
DogListView->Items->Clear();
for (int i = 0; i < DogList->Count; i++) {
TListItem * Item;
Item = DogListView->Items->Add();
Item->Caption = DogList->Items[i]->firstName;
Item->SubItems->Add(DogList->Items[i]->lastName);
Item->SubItems->Add(DogList->Items[i]->ownerName);
Item->SubItems->Add(DogList->Items[i]->hours);
Item->SubItems->Add(DogList->Items[i]->dogNum);
}
}
There is an error on each line that contains DogList->

Answer 1

TList holds untyped void* pointers. Its Items[] property getter returns a void* pointer. You need to type-cast it in order to access your data fields:
// DO NOT use the OnCreate event in C++! Use the actual constructor instead...
__fastcall TDogReportForm::TDogReportForm(TComponent *Owner)
: TForm(Owner)
{
DogListView->Items->Clear();
for (int i = 0; i < DogList->Count; i++)
{
// use whatever your real type name is...
MyDogInfo *Dog = static_cast<MyDogInfo*>(DogList->Items[i]); // <-- type-cast needed!
TListItem *Item = DogListView->Items->Add();
Item->Caption = Dog->firstName;
Item->SubItems->Add(Dog->lastName);
Item->SubItems->Add(Dog->ownerName);
Item->SubItems->Add(Dog->hours);
Item->SubItems->Add(Dog->dogNum);
}
}
On a side note, instead of copying all of the dog information to the TListView, you might consider using the TListView in virtual mode (set OwnerData to true and assign an OnData event handler) so it can display the information directly from DogList on-demand when needed:
__fastcall TDogReportForm::TDogReportForm(TComponent *Owner)
: TForm(Owner)
{
DogListView->Items->Count = DogList->Count;
}
void __fastcall TDogReportForm::DogListViewData(TObject *Sender, TListItem *Item)
{
// use whatever your real type name is...
MyDogInfo *Dog = static_cast<MyDogInfo*>(DogList->Items[Item->Index]);
Item->Caption = Dog->firstName;
Item->SubItems->Add(Dog->lastName);
Item->SubItems->Add(Dog->ownerName);
Item->SubItems->Add(Dog->hours);
Item->SubItems->Add(Dog->dogNum);
}
With that said, you should change DogList to use a different container that is more type-safe then TList, such as std::vector:
std::vector<MyDogInfo> DogList;
...
MyDogInfo &Dog = DogList[index]; // <-- no type-cast needed
Item->Caption = Dog.firstName;
Item->SubItems->Add(Dog.lastName);
Item->SubItems->Add(Dog.ownerName);
Item->SubItems->Add(Dog.hours);
Item->SubItems->Add(Dog.dogNum);