What is idiomatic is explicitly importing individual symbols into a name peace.

    #include <iostream>
    #include <vector>
    #include <string>
    
    using std::cout;
    using std::vector;
    using std::string;

    int main() { 
    
      vector<string> v {"explicit ", "is better ", "than implicit\n" };

      for (auto p: v) cout << p;
      
      return 0;
      
    }

But again, personal opinion - it can definitely be used in some contexts (just be consistent in your project!).