Check out example codes for "return 0; c++". It will help you in understanding the concepts better.

Code Example 1

return 0;// C++ The return value of the main function is considered the "Exit Status" of the application. On most operating systems returning 0 is a success status like saying "The program worked fine". In C++ it is optional to type " return 0; " at the end of the main function and the compiler includes it automatically

Code Example 2

// This example gives a reason why you should use using namespace std
#include <iostream>
using namespace std;
cout << "Hello "<<endl; /* this one is shorter*/
// without the using namespace std you will need to use this
std::cout <<"Hello"<<std::cout<<endl /* this one is longer 
and it requires shorter amount of time */

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