what is the equivalent in vc++ ?
int i = 0;
private TabPage[] tab = new TabPage[20];
i++;
tab[i] = new TabPage();
There is no equivalent in VC++. TabPage is GUI control; you can create something similar in C++ using Win API or maybe MFC, even Qt if you prefer it. If you want something equivalent in C++/CLI (.NET Framework again) you can create an array of TabPages:
array<TabPage^> ^ tabPage = gcnew array<TabPage^>(20);