show items value in memo - c++

Question

C++ Builder XE8
if i select Num 1 Memo will show Test
if i select other items memo will show Else Test
void __fastcall TForm1::FormCreate(TObject *Sender)
{
ListBox1->Items->Add("Num 1");
ListBox1->Items->Add("Num 2");
ListBox1->Items->Add("Num 3");
auto str = listBox1->SelectedItem->ToString();
if (str == L"Num 1") {
Memo1->Text = "Test";
}
else {
Memo1->Text = "Else Test";
}
}

Answer 1

The Form's OnCreate event (which you SHOULD NOT be using in C++, use the Form's constructor instead) is too soon to detect the user's selection, as the user has not had a chance to see the UI yet to select anything. Use the ListBox's OnChange event instead.
Also, TListBox does not have a SelectedItem property. In FireMonkey (which I assume you are using instead of VCL), it has a Selected property instead.
Try this:
__fastcall TForm1::TForm1(TComponent *Owner)
: TForm(Owner)
{
ListBox1->BeginUpdate();
try {
ListBox1->Items->Add("Num 1");
ListBox1->Items->Add("Num 2");
ListBox1->Items->Add("Num 3");
}
__finally {
ListBox1->EndUpdate();
}
}
void __fastcall TForm1::ListBox1Change(TObject *Sender)
{
TListBoxItem *Item = ListBox1->Selected;
if (Item) {
String str = ListBox1->Selected->Text;
if (str == L"Num 1") {
Memo1->Text = "Test";
}
else {
Memo1->Text = "Else Test";
}
}
else {
Memo1->Text = "Nothing";
}
}