std::cout, std::wcout - cppreference.com

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# 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 (as long as `<iostream>` is included).

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

Once initialized, std::cout is tie()'d to std::cin and std::wcout is tie()'d to std::wcin, meaning that any input operation on std::cin executes std::cout.flush() (via std::basic_istream::sentry's constructor).

Once initialized, std::cout is also tie()'d to std::cerr and std::wcout is tie()'d to std::wcerr, meaning that any output operation on std::cerr executes std::cout.flush() (via std::basic_ostream::sentry's constructor) (since C++11)

### [edit] 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

### [edit] See also

Init | initializes standard stream objects (public member class of `std::ios_base`) [edit]
clogwclog | writes to the standard C error stream stderr (global object) [edit]
coutwcout | writes to the standard C output stream stdout (global object) [edit]

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