Implementing Linux 'shutdown' from within a GTK application

I have written an application on Raspbian using GTK 3. Overall, it has gone well, but now I need to shutdown the Pi from within the application. When the condition occurs, I run the following code:

        /* Kick off the shutdown task. */
        ShutdownProc= g_subprocess_new(G_SUBPROCESS_FLAGS_NONE,
                         &serror,
                         "/usr/bin/sudo",
                         "/usr/bin/shutdown",
                         "-h",
                         "+1",
                         NULL);
        if (NULL == ShutdownProc) {
            g_warning ("Shutdown failed: %s", serror->message);
        }

The intent is to kick off the shutdown task with time to allow the application to shut down cleanly. I don’t get any error message, but the system does not shut down as expected.

Have I missed something?
Thanks

I found that changing the line specifying the shutdown command from ‘/usr/bin/shutdown’ to just ‘shutdown’ worked.

Apparently after issuing the sudo command, the full path is not required.