Omitting Namespace
You might see some C++ programs that run without the standard namespace library. The using namespace std line can be omitted and replaced with the std keyword, followed by the :: operator for string (and cout) objects:
Example
#include <iostream>
#include <string>
// using namespace std; - Remove this line
int main() {
std::string greeting = "Hello";
std::cout << greeting;
return 0;
}