C++ get PID using system

I am running a file using system, but I don't know how开发者_开发问答 to get the PID of that process. Does anybody know how to?

You might want to use fork and exec instead of system. The child process pid will be returned from fork to the parent process.

Edit in case it wasn't obvious, my answer was before the author tagged his post with windows. My answer is specific to Linux.