Adding a string to a listbox results in weird characters - c++

Question

I have made a function that send strings to listbox using WIN32
char data[] = "abcd";
addToList(hWnd,data);
void addToList(HWND hWnd,char data[] ){
SendMessage(GetDlgItem(hWnd,IDC_LISTBOX),LB_ADDSTRING,0,(LPARAM)data);
}
when I execute this it's send data to list box but the problem they appeared in weird characters, I have tried wchar_t also but the problem still issued

Answer 1

First of all, you should be checking your API calls for errors. You need to check the return values of all your calls to API functions.
That said, given the code in the question,
SendMessage(GetDlgItem(hWnd,IDC_LISTBOX),LB_ADDSTRING,0,(LPARAM)data);
If that results in an item being added to the list box, then it means that GetDlgItem did indeed return a valid window handle, and data did indeed point to valid memory. In which case the only explanation for what you report is that the text encoded did not match.
So, we can assume that the SendMessage macro evaluates to SendMessageW. And since you are passing ANSI encoded text, that mismatch explains the symptoms. The function treats the text as UTF-16 encoded.
One obvious solution is to use SendMessageA instead. However, a better solution, in my view, would be to pass UTF-16 encoded data.
wchar_t data[] = L"abcd";
....
void addToList(HWND hWnd, const wchar_t *data)
{
SendMessage(GetDlgItem(hWnd,IDC_LISTBOX), LB_ADDSTRING, 0, (LPARAM)data);
}
Obviously your code would add in the error checking that I mentioned at the start.