Is there a way to reference cout without using namespace std or prefixing with std::?

Question

I'm pretty new to C++, and I'm using std::cout for debugging purposes.

Though, I'd really like to be able to just use cout rather than the whole std::cout thing. I know i could import the std namespace, but I've been explained it was a bad thing due to name clashing that can occur because of this.

Is there anyway to do this?

I tried

std::ostream cout = std::cout;

But I get

function "std::basic_ostream<_CharT, _Traits>::basic_ostream(const std::basic_ostream<_CharT, _Traits> &) [with _CharT=char, _Traits=std::char_traits<char>]" (declared at line 391 of "/usr/include/c++/5/ostream") cannot be referenced -- it is a deleted function

Please suggest.

Answer 1

Sure, with a using declaration :

using std::cout;

Usual health warnings about not doing this in header files, and limiting it to small scopes apply.

Answer 2

You can't copy streams (think about it, it just doesn't make sense), but you can get a reference to them:

std::ostream& my_cout = std::cout;

However, I would strongly advice you not to do so. If you see in some code std::cout you can be almost 100% certain that you know what it is. On the other hand a cout alone you should already look suspicious to you and a my_cout could really be anything. I know it is hard, but get used to type std:: , on the long run it will help you more than you need time to type those 5 letters.

Answer 3

Your way would be:

auto& cout = std::cout;

but you might simply do

using std::cout;

(with similar restriction than using namespace: not in namespace scope in header, ideally limiting the scope of using directive as much as possible)

Answer 4

Sorry, too low rating to comment, but why don't you just type

using std::cout;

at the top of the file and then just use cout . PS also answered at this post

Answer 5

One way is using-declaration , which introduces only std::cout instead of all names in std:: :

using std::cout;

The way you tried won't work - it's an attempt to copy std::cout to another object - and std::cout is not copyable.

Alternative is to use a reference:

std::ostream& cout = std::cout;

Now, cout points to std::cout instead of being its copy.

The second way can be useful, if you want to, for example, write a function without deciding whether it should output to cout , file or something else:

void func(std::ostream& output) {
    output << "works with cout, files, etc.";
}

Answer 6

If you're looking to abbreviate std::cout , it could be that what you are really looking for is dependency injection.

Remember that std::cout is a reference to a model of a std::ostream .

We can use that in our favour to make code more re-usable, testable and loosely coupled.

example:

#include <iostream>
#include <sstream>

std::ostream& do_something(std::ostream& os)
{
    os << "Hello, World!\n";
    return os;
}


int main()
{
    // inject std::cout
    do_something(std::cout);

    // inject a stringstream
    std::ostringstream ss;
    do_something(ss);
    std::cout << ss.str();
}