I want to learn multithreading in C++. somewhere on internet I got a piece of code using popen() function of stdio.h. I just wanted to know that if this function helps in creating the new threads or it doesn't come under multithreading.

Please guide me in multithreading.

popen creates another process and manages the pipe setup for you.
It calls fork (in linux) and I'm not sure how the child process is executed in Windows.
This is different than using something such as pthreads to run multiple threads in the same process space.