I wrote a simple C++ program that edits the system PATH environment variable. However, to reflect the changes of the new PATH variable, the document at https://msdn.microsoft.com/en-us/library/windows/desktop/ms682653(v=vs.85).aspx mentions the need to broadcast a WM_SETTINGSCHANGE message to reflect the changes. To do this, I'm using the following piece of code:

SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0, (LPARAM)"Environment", SMTO_ABORTIFHUNG, 5000, NULL);

Unfortunately this doesn't works for me and I have to either log off / restart or manually go to Control Panel > Edit environment variables for changes to automaically applied system-wide.

My original PATH variable before the chage is :

C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\iCLS\;C:\Program Files\Intel\Intel(R) Management Engine Components\iCLS\;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files\MATLAB\R2017a\runtime\win64;C:\Program Files\MATLAB\R2017a\bin;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\nodejs\

and after the change is:

C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\iCLS\;C:\Program Files\Intel\Intel(R) Management Engine Components\iCLS\;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files\MATLAB\R2017a\runtime\win64;C:\Program Files\MATLAB\R2017a\bin;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\nodejs\;C:\hcX-af\;