# std::cout, std::wcout

From cppreference.com
< cpp‎ | io

Defined in header `<iostream>` |  |
extern std::ostream cout; | (1) |
extern std::wostream wcout; | (2) |

The global objects `std::cout` and `std::wcout` control output to a stream buffer of implementation-defined type (derived from std::streambuf), associated with the standard C output stream stdout.

These objects are guaranteed to be initialized during or before the first time an object of type std::ios_base::Init is constructed and are available for use in the constructors and destructors of static objects with ordered initialization (as long as `<iostream>` is included before the object is defined).

Unless std::ios_base::sync_with_stdio(false) has been issued, it is safe to concurrently access these objects from multiple threads for both formatted and unformatted output.

By specification of std::cin, std::cin.tie() returns &std::cout. This means that any input operation on `std::cin` executes std::cout.flush() (via std::basic_istream::sentry's constructor). Similarly, std::wcin.tie() returns &std::wcout.

By specification of std::cerr, std::cerr.tie() returns &std::cout. This means that any output operation on `std::cerr` executes std::cout.flush() (via std::basic_ostream::sentry's constructor). Similarly, std::wcerr.tie() returns &std::wcout. (since C++11)

### Notes

The 'c' in the name refers to "character" (stroustrup.com FAQ); `cout` means "character output" and `wcout` means "wide character output".

Because dynamic initialization of templated variables are unordered, it is not guaranteed that `std::cout` has been initialized to a usable state before the initialization of such variables begins, unless an object of type std::ios_base::Init has been constructed.

### Example

Run this code

    #include <iostream>

    struct Foo
    {
        int n;
        Foo()
        {
            std::cout << "static constructor\n";
        }
        ~Foo()
        {
            std::cout << "static destructor\n";
        }
    };

    Foo f; // static object

    int main()
    {
        std::cout << "main function\n";
    }

Output:

    static constructor
    main function
    static destructor

### See also

Init | initializes standard stream objects (public member class of `std::ios_base`)
cerrwcerr | writes to the standard C error stream stderr, unbuffered (global object)
clogwclog | writes to the standard C error stream stderr (global object)
stdinstdoutstderr | expression of type FILE* associated with the input stream expression of type FILE* associated with the output stream expression of type FILE* associated with the error output stream (macro constant)

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