Explicit std:: Namespace

In this lesson, I use explicit std:: namespace qualifiers for types and objects from the C++ Standard Library, like std::cout and std::string, instead of a using namespace std; statement. There are a few reasons for this:

1. It makes it clear that these types and objects are from the Standard Library and not from the current project or some other library.
2. It avoids potential naming conflicts. If your code defines a function or variable with the same name as something in the std namespace, and you have a using namespace std; statement, you'll get a naming conflict. Using explicit std:: avoids this.
3. It's considered good practice in many codebases and style guides. While using namespace std; can be convenient for small examples or personal projects, it's often discouraged in larger codebases or when writing libraries.

For example, instead of:

1#include <iostream>
2using namespace std;
3
4int main() {
5  string message = "Hello, world!";
6  cout << message << endl;
7}

I would write:

1#include <iostream>
2
3int main() {
4  std::string message = "Hello, world!";
5  std::cout << message << std::endl;
6}

The explicit std:: makes it clear where string, cout, and endl are coming from.

There are situations where a using statement can be appropriate, like within a limited scope such as a function, but for clarity and to promote good habits, I generally avoid using namespace std; in examples.