You might see some C++ programs that runs without the standard namespace library. The using namespace std line can be omitted and replaced with the std keyword, followed by the :: operator for some objects:
Example
#include <iostream>
int main() {
std::cout << "Hello World!";
return 0;
}
int main() {
std::cout << "Hello World!";
return 0;
}
It is up to you if you want to include the standard namespace library or not.
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