Testing ErrorLevel works for console applications, but this won’t work if you’re trying to run a windowed application (e.g. Win32-based) from a command prompt.
A windowed application will run in the background, and control will return immediately to the command prompt (most likely with an ErrorLevel of zero to indicate that the process was created successfully).
When a windowed application eventually exits, its exit status is lost.
Instead of using the console-based C++ launcher mentioned elsewhere, though, a simpler alternative is to start a windowed application using the command prompt’s START /WAIT command.
This will start the windowed application, wait for it to exit, and then return control to the command prompt with the exit status of the process set in ErrorLevel.
start /wait something.exe
echo %errorlevel%