What is the difference between std::cout and std::wcout?

Question

In c++ what is the difference between std::cout and std::wcout?

They both control output to a stream buffer or print stuff to the console, or are they just alike ?

Annecorinne

The w versions of standard streams are for wide characters. – Doradorado

They don't "print to the console". They write to stdout. Often, stdout is associated with a tty. Sometimes (rarely), the terminal you are using is a console. Don't conflate stdout with the terminal, and don't refer to your terminal as a "console". – Magalimagallanes

Answer 1

They operate on different character types:

• std::cout uses char as character type
• std::wcout uses wchar_t as character type

Otherwise both streams write to standard output.

Cosmo

but what are wide characters any way? – Annecorinne

char is used for narrow strings, suitable for 7-bit ASCII and 8-bit ANSI. wchar_t is used for wide strings, aka Unicode strings. However, the size of wchar_t is not portable, on some systems it is 16bit (suitable for UCS2/UTF-16), on others it is 32bit (suitable for UCS4/UTF-32). C++11 introduced new char16_t and char32_t types to deal with that descrepency. – Ruthenious

Does cout and wcout have their own buffer ？ – Laing

@xusisme I would guess they’d have different buffers as they store characters of different types and the std::basic_streambuf abstraction doesn’t handle chatacter encodings on this level. I don’t think there is defined synchronization between the narrow and wide character streams, i.e., alternately writing to each if them may cause blocks of characters being written, although with std::ios_base::sync_with_stdio(true) (the default) the characters are still not buffered. – Lefthand

@DietmarKühl So, what happens if I mix cout and wcout ? – Laing

@xusisme: as I said: I don't thin there is a defined order between them. If sync_with_stdio(false) was called, I would expect characters to be emitted in blocks from std::cout and std::wcout. With sync_with_stdio(true) the same may happen but I would guess that for most implementations things interleave the way they are written as sync_with_stdio(true) typically disables buffering of the standard streams. – Lefthand

Answer 2

Another thing is that both are used with respected input stream.

Objects of these are initialized during or before the first time an object of std::ios_base::Init is created.

• std::cout is std::basic_ios::tie'd to std::cin and to std::cerr
• std:wcout is std::basic_ios::tie'd to std::wcin and to std::wcerr

Balsam