Skip to main content

Close a Window Application from another application.

 This is just a demo application code to show how the WM_CLOSE message can be sent to the target process which has a titled window to close the application.

To achieve this, either we can use SendMessage or PostMessage APIs to send required Windows messages to the target application.

Though both the APIs are dispatching WM_XXXXX message to target application two APIs has some differences, these are as below:

1. SendMessage () call is a blocking call but PostMessage is a non-blocking call(Asynchronous)

2. SendMessage() APIs return type is LRESULT (LONG_PTR) but PostMessage() APIs return type is BOOL(typedef int). In Short, SendMessage () APIs return type depends on what message has been sent to the Windowed target process. For the other one, it's always a non-zero value, which indicates the message has been successfully placed on the target process message queue.

Now let's see how can I close a target windowed application "Solitaire & Casual Games" from my custom-made command prompt application. There are very few lines of code and it's very straightforward. We are getting / Seeking HWND of the target Windowed application by searching the window via FindWindow () API with the window title. Soon after that, we can shoot the message to the message WM_CLOSE to the target applications message queue via SendMessage or PostMessage. The sample code is here:

#include <iostream>
#include <windows.h>

int main() {
    // Find the main window handle of the target process.
    // In this case using FindWindow API to get the handle of the target process.
    // This technique only works for the process which has Window(UI with title)

    // 2nd Param is the title of the Window
    HWND targetWindow = FindWindow(nullptr, L"Solitaire & Casual Games"); 

    if (nullptr == targetWindow) 
        std::cout << "Target window not found." << std::endl;
        return 1;

    // Send the WM_CLOSE message to the target window
    SendMessage(targetWindow, WM_CLOSE, 0, 0);
    return 0;

Note: WM_CLOSE is a request to the target application to close but it may get ignored by the targeted windowed process. We will see soon how can we cleanly shut down a process (irrespective of windowed or not). There is an API named TerminateProcess() but it never terminates the process cleanly, I mean it doesn't detach dlls from the process, clean resources, etc. So will see soon how can we gracefully terminate a process from another custom process. 



Popular posts from this blog

Variadic template class to add numbers recursively during compilation

 The idea of having a class to add numbers (variable parameters) during compilation time recursively. Also wanted to restrict types to a single type while sending parameters to class member function. That said, if we mix int, float and double types to add function shall result in compilation error. How do we achieve this. The below is the code which actually helps to achieve this: <code> #include < fmt/format.h > template < typename T> class MyVarSumClass{     private :         T _sum = 0 ;     public :         template < typename ... TRest>         T add(T num, TRest... nums){             static_assert (std::conjunction<std::is_same<TRest, T>...>{}); /* Assert fails                if types are different */             _sum += num;             return add(nums...); // Next parameter packs gets picked recursively         }         // Base case         T add(T num){             _sum += num;             return _sum;         } }; int main() {     My

A simple approach to generate Fibonacci series via multi-threading

T his is a very simple approach taken to generate the Fibonacci series through multithreading. Here instead of a function, used a function object. The code is very simple and self-explanatory.  #include <iostream> #include <mutex> #include <thread> class Fib { public:     Fib() : _num0(1), _num1(1) {}     unsigned long operator()(); private:     unsigned long _num0, _num1;     std::mutex mu; }; unsigned long Fib::operator()() {     mu.lock(); // critical section, exclusive access to the below code by locking the mutex     unsigned long  temp = _num0;     _num0 = _num1;     _num1 = temp + _num0;     mu.unlock();     return temp; } int main() {     Fib f;          int i = 0;     unsigned long res = 0, res2= 0, res3 = 0;     std::cout << "Fibonacci series: ";     while (i <= 15) {         std::thread t1([&] { res = f(); }); // Capturing result to respective variable via lambda         std::thread t2([&] { res2 = f(); });         std::thread t3(

A concept to a product (Kimidori [ 黄緑]) - Part 2

In the previous part , we have seen KIMIDORI [ 黄緑] detect if a URL is malicious. In this part, we will see the details that KIMIDORI [ 黄緑] fetches out of the URL provided. As an example, provided a safe URL,, and let's see what it brings out: As we can see, the link is safe and the link is active, which means we can just click on the link to open it on IE.  Now it's time to look into the URL report (still under development):  We have URLs IP, Location, and HTTP Status code. The Report part is a sliding window, the Show Report button shows as well as hides the report. Show / Hide Report is a toggle button. Let's see if we get the same details for any bad (phishing / malicious) URL: Took an URL example from a phishing link and tested it. The tool detected it as not a good link (Screen Shot Below) & link does not activate unlike a safe URL: Now let's see the report part for more details including domain registration details: It looks like it&