How to execute a command and get output of command within C++ using POSIX?

Here we will see how to use the POSIX command through C++. The process is very simple, we have to use the function called system(). Inside this we have to pass string. That string will contain the POSIX command. 

The syntax is like below.

system(“command”)

Example

#include 
using namespace std;
int main () {
   cout 

Output
Print string using echo command
Hello World
Calculate math expression using bc
3.14285714285714285714