Stuck in a do while loop - c++

Question

Hello guys so here is my problem since i was stuck in this block of code for more then 2 day
i want to make my programe monitor a specifique application and wait for it to be lunch i tried the "Do and While loop" but its not working i have checked and rechecked and i couldnt find a solution for this problem
HWND hwnd = FindWindow(0,("my programme window name"));
do {
if(hwnd == nullptr ) { /* if the window has not beign found */
cout << "window not found!" << endl;
Sleep(1000);
system("cls");
}
}while(hwnd == nullptr);
/*******************************************************************/
starting the next code once the window of the programe has been found
so my problem is i keep getting ""window not found!" when i launch my own program first and then lunch the program wish i try to monitor , but when i start the program i wish to monitor then i launch my own program everything work fine
tnks for your help--- edit Problem sloved

Answer 1

You're not changing hwnd inside the loop. You need to call FindWindow() in the loop. You can use a regular while loop instead of do-while, so you don't need to do the call twice.
while ((hwnd = FindWindow(0, "my programme window name")) == nullptr) {
cout << "window not found!" << endl;
Sleep(1000);
system("cls");
}

Answer 2

First things first: Polling is wrong.
If you need to be informed that a certain window is created, use the tool that's specifically tailored for this. Set up a WinEvents hook (calling SetWinEventHook) that listens for EVENT_OBJECT_CREATE events. In your WinEventProc callback you can filter out the your window of interest, by inspecting it's window title, window class, certain styles (and combinations thereof).
This doesn't waste resources like your attempt to poll every second, and doesn't exhibit the race conditions either (e.g. missing a window because it was created and destroyed in between sampling points).

Answer 3

Assuming that the value of hwnd was nullptr when it entered the loop; you are not changing its value in the loop. Since the condition hwnd == nullptr is always true, you get an infinite loop.
In order to overcome this issue, you need to change the value of hwnd inside your loop.

Answer 4

Nothing in your loop changes hwnd, so it is impossible to get out of the loop (as you've seen).
You need to make something inside the loop change hwnd so that it is possible that (eventually) hwnd won't == nullptr. e.g. hwnd = FindWindow(0,("my programme window name"));
I'd refactor to:
HWND hwnd = FindWindow(0,("my programme window name"));
while(hwnd == nullptr)
{
cout << "window not found!" << endl;
Sleep(1000);
system("cls");
hwnd = FindWindow(0,("my programme window name"));
}

Answer 5

I think the problem is "FindWindow(0,("my programme window name"))" can't return an available hwnd so the loop is stuck.
Maybe you can try 10 times, if hwnd was still null, break the loop or exit the program.
#define MAX_COUNT 10
HWND hwnd = FindWindow(0,("my programme window name"));
int count = 0;
while(hwnd == nullptr && count < MAX_COUNT) {
count++;
cout << "window not found!" << endl;
Sleep(1000);
system("cls");
hwnd = FindWindow(0,("my programme window name"));
}