问题
can't get "wcout" to print unicode string in multiple code pages, together with leaving "cout" to work
please help me get these 3 lines to work together.
std::wcout<<"abc "<<L'\u240d'<<" defg "<<L'א'<<" hijk"<<std::endl;
std::cout<<"hello world from cout! \n";
std::wcout<<"hello world from wcout! \n";
output:
abc hello world from cout!
i tried:
#include <io.h>
#include <fcntl.h>
_setmode(_fileno(stdout), _O_U8TEXT);
problem: "cout" failed
tried:
std::locale mylocale("");
std::wcout.imbue(mylocale);
and:
SetConsoleOutputCP(1251);
and
setlocale(LC_ALL, "");
and
SetConsoleCP(CP_UTF8)
Nothing worked
回答1:
C++ says:
[C++11: 27.4.1/3]:Mixing operations on corresponding wide- and narrow-character streams follows the same semantics as mixing such operations onFILEs, as specified in Amendment 1 of the ISO C standard.
And the referenced document says:
The definition of a stream was changed to include the concept of an orientation for both text and binary streams. After a stream is associated with a file, but before any operations are performed on the stream, the stream is without orientation. If a wide-character input or output function is applied to a stream without orientation, the stream becomes wide-oriented. Likewise, if a byte input or output operation is applied to a stream with orientation, the stream becomes byte-oriented. Thereafter, only the
fwide()orfreopen()functions can alter the orientation of a stream.Byte input/output functions shall not be applied to a wide-oriented stream and wide-character input/output functions shall not be applied to a byte-oriented stream.
By my interpretation this means, in short, do not mix std::cout and std::wcout.
回答2:
Microsoft requires a bit of non-standard set-up with _setmode() before wcout or wcin can work. This example is pretty heavy on the boilerplate, so not as clear as it could possibly be, but it runs on clang++, g++ and MSVC++:
#include <iostream>
#include <locale>
#include <locale.h>
#include <stdlib.h>
#ifndef MS_STDLIB_BUGS // Allow overriding the autodetection.
/* The Microsoft C and C++ runtime libraries that ship with Visual Studio, as
* of 2017, have a bug that neither stdio, iostreams or wide iostreams can
* handle Unicode input or output. Windows needs some non-standard magic to
* work around that. This includes programs compiled with MinGW and Clang
* for the win32 and win64 targets.
*/
# if ( _MSC_VER || __MINGW32__ || __MSVCRT__ )
/* This code is being compiled either on MS Visual C++, or MinGW, or
* clang++ in compatibility mode for either, or is being linked to the
* msvcrt.dll runtime.
*/
# define MS_STDLIB_BUGS 1
# else
# define MS_STDLIB_BUGS 0
# endif
#endif
#if MS_STDLIB_BUGS
# include <io.h>
# include <fcntl.h>
#endif
#if !HAS_APP17_FILESYSTEM && !HAS_TS_FILESYSTEM && __has_include(<filesystem>)
# include <filesystem> /* MSVC has this header, but not the standard API. */
# if __cpp_lib_filesystem >= 201703
# define HAS_CPP17_FILESYSTEM 1
# endif
#endif
#if !HAS_CPP17_FILESYSTEM && __has_include(<experimental/filesystem>)
# include <experimental/filesystem>
/* Microsoft screws this one up, too, by not defining the feature-test
* macro specified by the standard.
*/
# if __cpp_lib_experimental_filesystem >= 201406 || MS_STDLIB_BUGS
# define HAS_TS_FILESYSTEM 1
/* With g++6, this requires -lstdc++fs, AFTER this source file on the
* command line.
*/
# endif
#endif
#if HAS_CPP17_FILESYSTEM
using std::filesystem::absolute;
using std::filesystem::current_path;
using std::filesystem::directory_entry;
using std::filesystem::directory_iterator;
using std::filesystem::is_directory;
using std::filesystem::exists;
using std::filesystem::path;
#elif HAS_TS_FILESYSTEM
using std::experimental::filesystem::absolute;
using std::experimental::filesystem::current_path;
using std::experimental::filesystem::directory_entry;
using std::experimental::filesystem::directory_iterator;
using std::experimental::filesystem::is_directory;
using std::experimental::filesystem::exists;
using std::experimental::filesystem::path;
#else
# error "This library has neither <filesystem> nor <experimental/filesystem>."
#endif
void init_locale(void)
// Does magic so that wcout can work.
{
#if MS_STDLIB_BUGS
// Windows needs a little non-standard magic.
constexpr char cp_utf16le[] = ".1200"; // UTF-16 little-endian locale.
setlocale( LC_ALL, cp_utf16le );
_setmode( _fileno(stdout), _O_WTEXT );
/* Repeat for _fileno(stdin), if needed. */
#else
// The correct locale name may vary by OS, e.g., "en_US.utf8".
constexpr char locale_name[] = "";
setlocale( LC_ALL, locale_name );
std::locale::global(std::locale(locale_name));
std::wcin.imbue(std::locale())
std::wcout.imbue(std::locale());
#endif
}
using std::endl;
int main( const int argc, const char * const argv[] )
{
init_locale();
const path cwd = (argc > 1) ? absolute(path( argv[1], std::locale() ))
: absolute(current_path());
if (exists(cwd)) {
std::wcout << cwd.wstring() << endl;
} else {
std::wcerr << "Path does not exist.\n";
return EXIT_FAILURE;
}
if (is_directory(cwd)) {
for ( const directory_entry &f : directory_iterator(cwd) )
std::wcout << f.path().filename().wstring() << endl;
}
return EXIT_SUCCESS;
}
That’s probably a lot more complicated than it really needed to be: std::filesystem is unsupported as of 2018, but <experimental/filesystem> is never going to be removed.
Here’s a simplified version that includes only the boilerplate to get wcout to work:
#include <iostream>
#include <locale>
#include <locale.h>
#ifndef MS_STDLIB_BUGS
# if ( _MSC_VER || __MINGW32__ || __MSVCRT__ )
# define MS_STDLIB_BUGS 1
# else
# define MS_STDLIB_BUGS 0
# endif
#endif
#if MS_STDLIB_BUGS
# include <io.h>
# include <fcntl.h>
#endif
void init_locale(void)
{
#if MS_STDLIB_BUGS
constexpr char cp_utf16le[] = ".1200";
setlocale( LC_ALL, cp_utf16le );
_setmode( _fileno(stdout), _O_WTEXT );
#else
// The correct locale name may vary by OS, e.g., "en_US.utf8".
constexpr char locale_name[] = "";
setlocale( LC_ALL, locale_name );
std::locale::global(std::locale(locale_name));
std::wcin.imbue(std::locale())
std::wcout.imbue(std::locale());
#endif
}
回答3:
It's because Unicode is not representable in the codepage causing wcout to fail.
std::wcout<<"abc "<<L'\u240d'<<" defg "<<L'א'<<" hijk"<<std::endl;
if(std::wcout.fail()){
std::cout<<"\nConversion didn't succeed\n";
std::wcout << "This statement has no effect on the console";
std::wcout.clear();
std::wcout<<"hello world from wcout! \n";
}
std::cout<<"hello world from cout! \n";
std::wcout<<"hello world from wcout again! \n";
来源：https://stackoverflow.com/questions/22950412/c-cant-get-wcout-to-print-unicode-and-leave-cout-working