Another simple of going this is get the return using the marco WEXITSTATUS. Pretty much the same way that you get return values of child process using waitpid call (in Unix based systems).
Here is the sample program. I have one C/C++ program, and one simple bash script.
Sample bash script
#!/bin/bash
echo "I am in Script"
exit 5;
Sample C/C++ program
int i, ret = system("./b.sh 2>&1 > /dev/null");
i=WEXITSTATUS(ret);
printf("My val= %d\n",i);
Output
./a.out
My val= 5
If you want more advanced approach to have multiple return code from the script or want an interactive session then perhaps you should use popen
Hope this helps.
system()call? For example, en.cppreference.com/w/cpp/utility/program/system