I've learned that typing
using namespace std;
at the beginning of a program is a bad habit, because it includes every function in the namespace. This risks causing errors if there is a name collision.
My question is, does there exist a way to specify which namespace functions you don't want to use? Is there some statement, such as
not_using std::cin;
that can accomplish this?
You cannot do that (include everything and then selectively exclude something).
Your options are:
1) always explicitly qualify names. Like std::vector<int> v;
2) pull in all names with using namespace std;
3) pull in just the names you need with, for example, using std::vector; and then do vector<int> v; - names other than "vector" are not pulled in.
Note: using namespace std; doesn't have to go at global scope and pollute the entire file. You can do it inside a function if you want:
void f() {
using namespace std;
// More code
}
That way, only f() pulls in all names in its local scope. Same goes for using std::vector; etc.
You can using ns_name::name; just the name's you want unqualified access to.
Instead of using global namespace scope, use this syntax : For example : std::cout :
For more examples read this : http://www.cplusplus.com/doc/tutorial/namespaces/
