Note:
To run a program from your program you can use the calls system() (man system )and the exec() family of functions (man 3 exec).
To make your programs 'talk' with each other you can see the pipe() (man pipe ), dup() (man dup) . It could also be interessing to take a look at the fork()
Note that what as said above could be used within a C program but I think that you should be able to use it with your C++ programs too .
Hope that helps ... and have fun