I am trying to get the Process ID of a program (PID) but for some odd reason, the PID changes. When the target program (Alarms & Clock) is visible, it gives me the wrong PID while having the program minimized gives me the right PID.
I am guessing that minimizing the target program suspends it's process, thus allowing it to be read. However, simply reading the PID should not be a restriction even when a process is running.
Does anyone have an idea on what am I doing wrong?
Currently Tried Methods:
ere is a working, concise piece of code that portrays the problem:
#include <iostream>
#include <Windows.h>
#include <string>
int main()
{
std::string window_name = "Alarms & Clock"; //Feel free to replace this with another program
HWND hwnd = FindWindowA(NULL, window_name.c_str());
if (!hwnd)
{
std::cerr << "Error: Could not find window" << std::endl;
return -1;
}
DWORD processID = 0;
GetWindowThreadProcessId(hwnd, &processID);
std::cout << "Process ID: " << processID << std::endl;
std::cin.get();
return 0;
}
I was able to regenerate the problem on my Win/10 with GCC 5.3. I tested it with the "Calculator" app. When the app's window was not minimized I got PID = 14440 which belonged to ApplicationFrameHost.exe, However, I got PID = 1936 correctly when calc's window is minimized.
This is due to the fact that "Calculator" is a tablet app and not a desktop app. Desktop apps give the right PID no matter if the window is minimized or not.
I think this SO post would be useful for you.
It seems that ApplicationFrameHost.exe is an app container that handle many child apps. An extra code is needed to retrieve the exact child app pid you are looking for.
base on that page, I wrote this piece of code and it worked for me, however, you might need to refine it.
typedef struct {
DWORD ownerpid;
DWORD childpid;
} windowinfo;
BOOL CALLBACK EnumChildWindowsCallback(HWND hWnd, LPARAM lp) {
windowinfo* info = (windowinfo*)lp;
DWORD pid = 0;
GetWindowThreadProcessId(hWnd, &pid);
if (pid != info->ownerpid) info->childpid = pid;
return TRUE;
}
void Show_PID()
{
Sleep(1000);
std::string window_name = "Calculator";
HWND hwnd = FindWindowA(NULL, window_name.c_str());
windowinfo info = { 0 };
GetWindowThreadProcessId(hwnd, &info.ownerpid);
info.childpid = info.ownerpid;
EnumChildWindows(hwnd, EnumChildWindowsCallback, (LPARAM)&info);
std::cout << "Process ID: " << info.childpid << std::endl;
}
int main()
{
for (int i = 0; i < 9; ++i)
{
Show_PID();
}
return 0;
}
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