Using string literals without using namespace std

Question

There's recommendation in C++ community to not to use using namespace std;. But suppose you want to use string literals e.g. auto s = "dummy"s;. Not using using namespace std; cause to failed compile. What is the solution?

Answer 1

operator""s is in 2 inlined namespaces in namespace std. It basically looks like this:

namespace std {     inline namespace literals     {         inline namespace string_literals         {             //operator""s implementation             //...         }     } } 

So, to only get the string literals, use using namespace std::string_literals;.

Alternatevely, if you want to include every literal - including the string literals (like s for seconds if you include chrono, ...): using namespace std::literals;.

Depending on the situation, you might also consider using:

using std::string_literals::operator""s; 

instead of importing every name from that namespace.

Note that you should still not include it in a header, at global level (but you can do it inside inline or member functions or namespaces you control)