How do I execute a command and get the output of the command within C++ using POSIX?

I am looking for a way to get the output of a command when it is run from within a C++ program. I have looked at using the system() function, but that will just execute a command. Here's an example of what I'm looking for:

std::string result = system("./some_command");

I need to run an arbitrary command and get its output. I've looked at boost.org, but I have not found anything that will give me what I need.