launching ros launch file from program

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I am developing a UI based on qt qml. Here i have succesfully used the roscpp client library to interface with ros. But i haven't found a way to launch ros launhc files from c++ program. I found that system function can be used but looks like this function is not portable and not suitable. How can i launch a ros launch file such that ros launch files can be launched from c++ file?

Here my requirement is to launch ros nodes present on remote raspberry pi from local computering running qt qml application with roscpp as client library to communicate with remote robots.