Namespaces

A namespace groups related names to avoid collisions between libraries — std::cout means "cout, from the std namespace," the same way a package qualifies a class name in Java.

namespace mymath {
    int square(int x) {
        return x * x;
    }
}

std::cout << mymath::square(4) << std::endl; // 16

Common mistakes

• Writing using namespace std; at the top of every file — it's common in small examples (this course avoids it, spelling out std:: explicitly instead) but in larger projects it reintroduces exactly the naming collisions namespaces exist to prevent.