How to convert wstring into string

Question

The question is how to convert wstring to string   I have next example     include  lt string gt   include  lt iostream gt   int main         std  wstring ws   L Hello       std  string s  ws begin    ws end           std  cout  lt  lt  std  string         lt  lt s lt  lt std  endl      std  wcout lt  lt  std  wstring        lt  lt ws lt  lt std  endl      std  cout  lt  lt  std  string         lt  lt s lt  lt std  endl      the output with commented out line is    std  string       Hello std  wstring      Hello std  string       Hello   but without is only    std  wstring      Hello   Is anything wrong in the example  Can I do the conversion like above   EDIT  New example  taking into account some answers  is    include  lt string gt   include  lt iostream gt   include  lt sstream gt   include  lt locale gt   int main         setlocale LC CTYPE            const std  wstring ws   L Hello       const std  string s  ws begin    ws end           std  cout lt  lt  std  string         lt  lt s lt  lt std  endl      std  wcout lt  lt  std  wstring        lt  lt ws lt  lt std  endl       std  stringstream ss      ss  lt  lt  ws c str        std  cout lt  lt  std  stringstream         lt  lt ss str   lt  lt std  endl      The output is    std  string       Hello std  wstring      Hello std  stringstream       0x860283c   therefore the stringstream can not be used to convert wstring into string

User · Accepted Answer

Here is a worked-out solution based on the other suggestions:

#include <string>
#include <iostream>
#include <clocale>
#include <locale>
#include <vector>

int main() {
  std::setlocale(LC_ALL, "");
  const std::wstring ws = L"hëllö";
  const std::locale locale("");
  typedef std::codecvt<wchar_t, char, std::mbstate_t> converter_type;
  const converter_type& converter = std::use_facet<converter_type>(locale);
  std::vector<char> to(ws.length() * converter.max_length());
  std::mbstate_t state;
  const wchar_t* from_next;
  char* to_next;
  const converter_type::result result = converter.out(state, ws.data(), ws.data() + ws.length(), from_next, &to[0], &to[0] + to.size(), to_next);
  if (result == converter_type::ok or result == converter_type::noconv) {
    const std::string s(&to[0], to_next);
    std::cout <<"std::string =     "<<s<<std::endl;
  }
}

This will usually work for Linux, but will create problems on Windows.

User · Answer

In my case  I have to use multibyte character  MBCS   and I want to use std  string and std  wstring  And can t use c  11  So I use mbstowcs and wcstombs   I make same function with using new  delete     but it is slower then this   This can help How to  Convert Between Various String Types  EDIT  However  in case of converting to wstring and source string is no alphabet and multi byte string  it s not working  So I change wcstombs to WideCharToMultiByte    include  lt string gt   std  wstring get wstr from sz const char  psz          I think it s enough to my case     wchar t buf 0x400       wchar t  pbuf   buf      size t len   strlen psz    1       if  len  gt   sizeof buf    sizeof wchar t                 pbuf   L error             else               size t converted          mbstowcs s  amp converted  buf  psz   TRUNCATE              return std  wstring pbuf      std  string get string from wsz const wchar t  pwsz        char buf 0x400       char  pbuf   buf      size t len   wcslen pwsz  2   1       if  len  gt   sizeof buf                 pbuf    error             else               size t converted          wcstombs s  amp converted  buf  pwsz   TRUNCATE              return std  string pbuf       EDIT to use  MultiByteToWideChar  instead of  wcstombs    include  lt Windows h gt   include  lt boost shared ptr hpp gt   include  string util h   std  wstring get wstring from sz const char  psz        int res      wchar t buf 0x400       wchar t  pbuf   buf      boost  shared ptr lt wchar t   gt  shared pbuf       res   MultiByteToWideChar CP ACP  0  psz  -1  buf  sizeof buf  sizeof wchar t         if  0    res  amp  amp  GetLastError      ERROR INSUFFICIENT BUFFER                res   MultiByteToWideChar CP ACP  0  psz  -1  NULL  0            shared pbuf   boost  shared ptr lt wchar t   gt  new wchar t res             pbuf   shared pbuf get             res   MultiByteToWideChar CP ACP  0  psz  -1  pbuf  res             else if  0    res                pbuf   L error              return std  wstring pbuf      std  string get string from wcs const wchar t  pcs        int res      char buf 0x400       char  pbuf   buf      boost  shared ptr lt char   gt  shared pbuf       res   WideCharToMultiByte CP ACP  0  pcs  -1  buf  sizeof buf   NULL  NULL        if  0    res  amp  amp  GetLastError      ERROR INSUFFICIENT BUFFER                res   WideCharToMultiByte CP ACP  0  pcs  -1  NULL  0  NULL  NULL            shared pbuf   boost  shared ptr lt char   gt  new char res             pbuf   shared pbuf get             res   WideCharToMultiByte CP ACP  0  pcs  -1  pbuf  res  NULL  NULL             else if  0    res                pbuf    error              return std  string pbuf

User · Answer

include  lt boost locale hpp gt  namespace lcv   boost  locale  conv   inline std  wstring fromUTF8 const std  string amp  s    return lcv  utf to utf lt wchar t gt  s      inline std  string toUTF8 const std  wstring amp  ws    return lcv  utf to utf lt char gt  ws

User · Answer

Embarcadero C   Builder      convertion string to wstring string str1    hello   String str2   str1             typedef UnicodeString String    - gt  str2 contains now u hello       convertion wstring to string String str2   u hello   string str1   UTF8string str2  c str         - gt  str1 contains now  hello

User · Answer

Solution from  http   forums devshed com c-programming-42 wstring-to-string-444006 html      std  wstring wide  L Wide      std  string str  wide begin    wide end          Will print no problemo  std  cout  lt  lt  str  lt  lt  std  endl      Beware that there is no character set conversion going on here at all  What this does is simply to assign each iterated wchar t to a char - a truncating conversion  It uses the std  string c tor    template lt  class InputIt  gt  basic string  InputIt first  InputIt last                const Allocator amp  alloc   Allocator        As stated in comments      values 0-127 are identical in virtually every encoding  so truncating   values that are all less than 127 results in the same text  Put in a   chinese character and you ll see the failure    -     the values 128-255 of windows codepage 1252  the Windows English   default  and the values 128-255 of unicode are mostly the same  so if   that s teh codepage you re using most of those characters should be   truncated to the correct values   I totally expected    and    to work    I know our code at work relies on this for     which I will soon fix    And note that code points in the range 0x80 - 0x9F in Win1252 will not work  This includes

User · Answer

I am using below to convert wstring to string   std  string strTo  char  szTo   new char someParam length     1   szTo someParam size        0   WideCharToMultiByte CP ACP  0  someParam c str    -1  szTo   int someParam length    NULL  NULL   strTo   szTo  delete szTo

User · Answer

You might as well just use the ctype facet s narrow method directly     include  lt clocale gt   include  lt locale gt   include  lt string gt   include  lt vector gt   inline std  string narrow std  wstring const  text        std  locale const loc          wchar t const  from   text c str        std  size t const len   text size        std  vector lt char gt  buffer len   1       std  use facet lt std  ctype lt wchar t gt   gt  loc  narrow from  from   len        buffer 0        return std  string  buffer 0    buffer len

User · Answer

Default encoding on    Windows UTF-16  Linux UTF-8  MacOS UTF-8    My solution Steps  includes null chars  0  avoid truncated   Without using functions on windows h header    Add Macros to detect Platform  Windows Linux and others     Create function to convert std  wstring to std  string and inverse std  string to std  wstring     Create function for print     Print std  string  std  wstring   Check RawString Literals  Raw String Suffix  Linux Code  Print directly std  string using std  cout  Default Encoding on Linux is UTF-8  no need extra functions  On Windows if you need to print unicode  We can use WriteConsole for print unicode chars from std  wstring  Finally on Windows  You need a powerfull and complete view support for unicode chars in console  I recommend Windows Terminal QA   Tested on Microsoft Visual Studio 2019 with VC    std c  17   Windows Project  Tested on repl it using Clang compiler  std c  17     Q  Why you not use  lt codecvt gt  header functions and classes   A  Deprecate  Removed or deprecated features impossible build on VC    but no problems on g    I prefer 0 warnings and headaches    Q  std   wstring is cross platform  A  No  std  wstring uses wchar t elements  On Windows wchar t size is 2 bytes  each character is stored in UTF-16 units  if character is bigger than  U FFFF  the character is represented in two UTF-16 units 2 wchar t elements  called surrogate pairs  On Linux wchar t size is 4 bytes each character is stored in one wchar t element  no needed surrogate pairs  Check Standard data types on UNIX  Linux  and Windowsl    Q  std   string is cross platform  A  Yes  std  string uses char elements  char type is guaranted that is same byte size in most compilers  char type size is 1 byte  Check Standard data types on UNIX  Linux  and Windowsl   Full example code   include  lt iostream gt   include  lt set gt   include  lt string gt   include  lt locale gt      WINDOWS  if   WIN32   include  lt Windows h gt   include  lt conio h gt   define WINDOWS PLATFORM 1  define DLLCALL STDCALL  define DLLIMPORT  declspec dllimport   define DLLEXPORT  declspec dllexport   define DLLPRIVATE  define NOMINMAX    EMSCRIPTEN  elif defined   EMSCRIPTEN     include  lt emscripten emscripten h gt   include  lt emscripten bind h gt   include  lt unistd h gt   include  lt termios h gt   define EMSCRIPTEN PLATFORM 1  define DLLCALL  define DLLIMPORT  define DLLEXPORT   attribute    visibility  quot default quot      define DLLPRIVATE   attribute    visibility  quot hidden quot         LINUX - Ubuntu  Fedora    Centos  Debian  RedHat  elif    LINUX        gnu linux        linux        linux    linux   define LINUX PLATFORM 1  include  lt unistd h gt   include  lt termios h gt   define DLLCALL CDECL  define DLLIMPORT  define DLLEXPORT   attribute    visibility  quot default quot      define DLLPRIVATE   attribute    visibility  quot hidden quot      define CoTaskMemAlloc p  malloc p   define CoTaskMemFree p  free p     ANDROID  elif    ANDROID      ANDROID   define ANDROID PLATFORM 1  define DLLCALL  define DLLIMPORT  define DLLEXPORT   attribute    visibility  quot default quot      define DLLPRIVATE   attribute    visibility  quot hidden quot        MACOS  elif defined   APPLE     include  lt unistd h gt   include  lt termios h gt   define DLLCALL  define DLLIMPORT  define DLLEXPORT   attribute    visibility  quot default quot      define DLLPRIVATE   attribute    visibility  quot hidden quot      include  quot TargetConditionals h quot   if TARGET OS IPHONE  amp  amp  TARGET IPHONE SIMULATOR  define IOS SIMULATOR PLATFORM 1  elif TARGET OS IPHONE  define IOS PLATFORM 1  elif TARGET OS MAC  define MACOS PLATFORM 1  else   endif   endif    typedef std  string String  typedef std  wstring WString    define EMPTY STRING u8 quot  quot s  define EMPTY WSTRING L quot  quot s  using namespace std  literals  string literals   class Strings   public      static String WideStringToString const WString amp  wstr                if  wstr empty                          return String                      size t pos          size t begin   0          String ret    if WINDOWS PLATFORM         int size          pos   wstr find static cast lt wchar t gt  0   begin           while  pos    WString  npos  amp  amp  begin  lt  wstr length                          WString segment   WString  amp wstr begin   pos - begin               size   WideCharToMultiByte CP UTF8  WC ERR INVALID CHARS   amp segment 0   segment size    NULL  0  NULL  NULL               String converted   String size  0               WideCharToMultiByte CP UTF8  WC ERR INVALID CHARS   amp segment 0   segment size     amp converted 0   converted size    NULL  NULL               ret append converted               ret append   0                 begin   pos   1              pos   wstr find static cast lt wchar t gt  0   begin                     if  begin  lt   wstr length                          WString segment   WString  amp wstr begin   wstr length   - begin               size   WideCharToMultiByte CP UTF8  WC ERR INVALID CHARS   amp segment 0   segment size    NULL  0  NULL  NULL               String converted   String size  0               WideCharToMultiByte CP UTF8  WC ERR INVALID CHARS   amp segment 0   segment size     amp converted 0   converted size    NULL  NULL               ret append converted              elif LINUX PLATFORM    MACOS PLATFORM    EMSCRIPTEN PLATFORM         size t size          pos   wstr find static cast lt wchar t gt  0   begin           while  pos    WString  npos  amp  amp  begin  lt  wstr length                          WString segment   WString  amp wstr begin   pos - begin               size   wcstombs nullptr  segment c str    0               String converted   String size  0               wcstombs  amp converted 0   segment c str    converted size                 ret append converted               ret append   0                 begin   pos   1              pos   wstr find static cast lt wchar t gt  0   begin                     if  begin  lt   wstr length                          WString segment   WString  amp wstr begin   wstr length   - begin               size   wcstombs nullptr  segment c str    0               String converted   String size  0               wcstombs  amp converted 0   segment c str    converted size                 ret append converted              else         static assert false   quot Unknown Platform quot     endif         return ret             static WString StringToWideString const String amp  str                if  str empty                          return WString                       size t pos          size t begin   0          WString ret   ifdef WINDOWS PLATFORM         int size   0          pos   str find static cast lt char gt  0   begin           while  pos    std  string  npos                std  string segment   std  string  amp str begin   pos - begin               std  wstring converted   std  wstring segment size     1  0               size   MultiByteToWideChar CP UTF8  MB ERR INVALID CHARS   amp segment 0   segment size     amp converted 0   converted length                 converted resize size               ret append converted               ret append   0                 begin   pos   1              pos   str find static cast lt char gt  0   begin                     if  begin  lt  str length                  std  string segment   std  string  amp str begin   str length   - begin               std  wstring converted   std  wstring segment size     1  0               size   MultiByteToWideChar CP UTF8  MB ERR INVALID CHARS  segment c str    segment size     amp converted 0   converted length                 converted resize size               ret append converted               elif LINUX PLATFORM    MACOS PLATFORM    EMSCRIPTEN PLATFORM         size t size          pos   str find static cast lt char gt  0   begin           while  pos    String  npos                        String segment   String  amp str begin   pos - begin               WString converted   WString segment size    0               size   mbstowcs  amp converted 0    amp segment 0   converted size                 converted resize size               ret append converted               ret append   0                 begin   pos   1              pos   str find static cast lt char gt  0   begin                     if  begin  lt  str length                          String segment   String  amp str begin   str length   - begin               WString converted   WString segment size    0               size   mbstowcs  amp converted 0    amp segment 0   converted size                 converted resize size               ret append converted              else         static assert false   quot Unknown Platform quot     endif         return ret            enum class ConsoleTextStyle       DEFAULT   0      BOLD   1      FAINT   2      ITALIC   3      UNDERLINE   4      SLOW BLINK   5      RAPID BLINK   6      REVERSE   7      enum class ConsoleForeground       DEFAULT   39      BLACK   30      DARK RED   31      DARK GREEN   32      DARK YELLOW   33      DARK BLUE   34      DARK MAGENTA   35      DARK CYAN   36      GRAY   37      DARK GRAY   90      RED   91      GREEN   92      YELLOW   93      BLUE   94      MAGENTA   95      CYAN   96      WHITE   97     enum class ConsoleBackground       DEFAULT   49      BLACK   40      DARK RED   41      DARK GREEN   42      DARK YELLOW   43      DARK BLUE   44      DARK MAGENTA   45      DARK CYAN   46      GRAY   47      DARK GRAY   100      RED   101      GREEN   102      YELLOW   103      BLUE   104      MAGENTA   105      CYAN   106      WHITE   107     class Console   private      static void EnableVirtualTermimalProcessing          if defined WINDOWS PLATFORM         HANDLE hOut   GetStdHandle STD OUTPUT HANDLE           DWORD dwMode   0          GetConsoleMode hOut   amp dwMode           if    dwMode  amp  ENABLE VIRTUAL TERMINAL PROCESSING                         dwMode    ENABLE VIRTUAL TERMINAL PROCESSING              SetConsoleMode hOut  dwMode              endif            static void ResetTerminalFormat                 std  cout  lt  lt  u8 quot  033 0m quot              static void SetVirtualTerminalFormat ConsoleForeground foreground  ConsoleBackground background  std  set lt ConsoleTextStyle gt  styles                String format   u8 quot  033  quot           format append std  to string static cast lt int gt  foreground             format append u8 quot   quot            format append std  to string static cast lt int gt  background             if  styles size    gt  0                        for  auto it   styles begin    it    styles end      it                                format append u8 quot   quot                    format append std  to string static cast lt int gt   it                                     format append u8 quot m quot            std  cout  lt  lt  format        public      static void Clear           ifdef WINDOWS PLATFORM         std  system u8 quot cls quot     elif LINUX PLATFORM    defined MACOS PLATFORM         std  system u8 quot clear quot     elif EMSCRIPTEN PLATFORM         emscripten  val  global    quot console quot   call lt void gt  u8 quot clear quot     else         static assert false   quot Unknown Platform quot     endif            static void Write const String amp  s  ConsoleForeground foreground   ConsoleForeground  DEFAULT  ConsoleBackground background   ConsoleBackground  DEFAULT  std  set lt ConsoleTextStyle gt  styles              ifndef EMSCRIPTEN PLATFORM         EnableVirtualTermimalProcessing            SetVirtualTerminalFormat foreground  background  styles    endif         String str   s   ifdef WINDOWS PLATFORM         WString unicode   Strings  StringToWideString str           WriteConsole GetStdHandle STD OUTPUT HANDLE   unicode c str    static cast lt DWORD gt  unicode length     nullptr  nullptr    elif defined LINUX PLATFORM    defined MACOS PLATFORM    EMSCRIPTEN PLATFORM         std  cout  lt  lt  str   else         static assert false   quot Unknown Platform quot     endif   ifndef EMSCRIPTEN PLATFORM         ResetTerminalFormat     endif            static void WriteLine const String amp  s  ConsoleForeground foreground   ConsoleForeground  DEFAULT  ConsoleBackground background   ConsoleBackground  DEFAULT  std  set lt ConsoleTextStyle gt  styles                     Write s  foreground  background  styles           std  cout  lt  lt  std  endl             static void Write const WString amp  s  ConsoleForeground foreground   ConsoleForeground  DEFAULT  ConsoleBackground background   ConsoleBackground  DEFAULT  std  set lt ConsoleTextStyle gt  styles              ifndef EMSCRIPTEN PLATFORM         EnableVirtualTermimalProcessing            SetVirtualTerminalFormat foreground  background  styles    endif         WString str   s    ifdef WINDOWS PLATFORM         WriteConsole GetStdHandle STD OUTPUT HANDLE   str c str    static cast lt DWORD gt  str length     nullptr  nullptr    elif LINUX PLATFORM    MACOS PLATFORM    EMSCRIPTEN PLATFORM         std  cout  lt  lt  Strings  WideStringToString str    else         static assert false   quot Unknown Platform quot     endif   ifndef EMSCRIPTEN PLATFORM         ResetTerminalFormat     endif            static void WriteLine const WString amp  s  ConsoleForeground foreground   ConsoleForeground  DEFAULT  ConsoleBackground background   ConsoleBackground  DEFAULT  std  set lt ConsoleTextStyle gt  styles                     Write s  foreground  background  styles           std  cout  lt  lt  std  endl             static void WriteLine                 std  cout  lt  lt  std  endl             static void Pause                 char c          do                       c   getchar                std  cout  lt  lt   quot Press Key  quot   lt  lt  std  endl            while  c    64           std  cout  lt  lt   quot KeyPressed quot   lt  lt  std  endl             static int PauseAny bool printWhenPressed   false  ConsoleForeground foreground   ConsoleForeground  DEFAULT  ConsoleBackground background   ConsoleBackground  DEFAULT  std  set lt ConsoleTextStyle gt  styles                     int ch   ifdef WINDOWS PLATFORM         ch    getch     elif LINUX PLATFORM    MACOS PLATFORM    EMSCRIPTEN PLATFORM         struct termios oldt  newt          tcgetattr STDIN FILENO   amp oldt           newt   oldt          newt c lflag  amp     ICANON   ECHO           tcsetattr STDIN FILENO  TCSANOW   amp newt           ch   getchar            tcsetattr STDIN FILENO  TCSANOW   amp oldt    else         static assert false   quot Unknown Platform quot     endif         if  printWhenPressed                        Console  Write String 1  ch   foreground  background  styles                     return ch              int main         std  locale  global std  locale u8 quot en US UTF8 quot         auto str   u8 quot  0Hello 0123456789         123456789   quot s        WString wstr   L quot  0Hello 0123456789         123456789   quot s      WString wstrResult   Strings  StringToWideString str       String strResult   Strings  WideStringToString wstr       bool equals1   wstr    wstrResult      bool equals2   str    strResult       Console  WriteLine u8 quot    Converted Strings printed with Console  WriteLine quot s  ConsoleForeground  GREEN       Console  WriteLine wstrResult  ConsoleForeground  BLUE    Printed OK on Windows Linux      Console  WriteLine strResult  ConsoleForeground  BLUE    Printed OK on Windows Linux           Console  WriteLine u8 quot    Converted Strings printed with std  cout std  wcout quot s  ConsoleForeground  GREEN       std  cout  lt  lt  strResult  lt  lt  std  endl   Printed OK on Linux  BAD on Windows      std  wcout  lt  lt  wstrResult  lt  lt  std  endl    Printed BAD on Windows Linux      Console  WriteLine        Console  WriteLine u8 quot Press any key to exit quot s  ConsoleForeground  DARK GRAY       Console  PauseAny        You cant test this code on https   repl it  JomaCorpFX StringToWideStringToString main cpp    Screenshots   Using Windows Terminal  Using cmd powershell  Repl it capture

User · Answer

There are two issues with the code    The conversion in const std  string s  ws begin    ws end      is not required to correctly map the wide characters to their narrow counterpart  Most likely  each wide character will just be typecast to char  The resolution to this problem is already given in the answer by kem and involves the narrow function of the locale s ctype facet  You are writing output to both std  cout and std  wcout in the same program  Both cout and wcout are associated with the same stream  stdout  and the results of using the same stream both as a byte-oriented stream  as cout does  and a wide-oriented stream  as wcout does  are not defined  The best option is to avoid mixing narrow and wide output to the same  underlying  stream  For stdout cout wcout  you can try switching the orientation of stdout when switching between wide and narrow output  or vice versa     include  lt iostream gt   include  lt stdio h gt   include  lt wchar h gt   int main         std  cout  lt  lt   narrow   lt  lt  std  endl      fwide stdout  1      switch to wide     std  wcout  lt  lt  L wide   lt  lt  std  endl      fwide stdout  -1      switch to narrow     std  cout  lt  lt   narrow   lt  lt  std  endl      fwide stdout  1      switch to wide     std  wcout  lt  lt  L wide   lt  lt  std  endl

User · Answer

At the time of writing this answer  the number one google search for  convert string wstring  would land you on this page  My answer shows how to convert string to wstring  although this is NOT the actual question  and I should probably delete this answer but that is considered bad form   You may want to jump to this StackOverflow answer  which is now higher ranked than this page     Here s a way to combining string  wstring and mixed string constants to wstring  Use the wstringstream class    include  lt sstream gt   std  string narrow    narrow   std  wstring wide    wide    std  wstringstream cls  cls  lt  lt    abc    lt  lt  narrow c str    lt  lt  L  def    lt  lt  wide c str    std  wstring total  cls str

User · Answer

I spent many sad days trying to come up with a way to do this for C  17  which deprecated code cvt facets  and this is the best I was able to come up with by combining code from a few different sources  setlocale  LC ALL   quot en US UTF-8 quot       Invoked in main    std  string wideToMultiByte  std  wstring const  amp  wideString          std  string ret       std  string buff  MB CUR MAX    0           for   wchar t const  amp  wc   wideString                   int mbCharLen   std  wctomb   amp buff  0    wc              if   mbCharLen  lt  1     break              for   int i   0  i  lt  mbCharLen    i                             ret    buff  i                             return ret       std  wstring multiByteToWide  std  string const  amp  multiByteString           std  wstring ws  multiByteString size    L            ws resize            std  mbstowcs   amp ws  0                  multiByteString c str                  multiByteString size              return ws      I tested this code on Windows 10  and at least for my purposes  it seems to work fine  Please don t lynch me if this doesn t consider some crazy edge cases that you might need to handle  I m sure someone with more experience can improve on this   -  Also  credit where it s due  Adapted for wideToMultiByte   Copied for multiByteToWide

User · Answer

Besides just converting the types  you should also be conscious about the string s actual format   When compiling for Multi-byte Character set Visual Studio and the Win API assumes UTF8  Actually windows encoding which is Windows-28591    When compiling for Unicode Character set Visual studio and the Win API assumes UTF16   So  you must convert the string from UTF16 to UTF8 format as well  and not just convert to std  string  This will become necessary when working with multi-character formats like some non-latin languages   The idea is to decide that std  wstring always represents UTF16  And std  string always represents UTF8    This isn t enforced by the compiler  it s more of a good policy to have   Note the string prefixes I use to define UTF16  L  and UTF8  u8    To convert between the 2 types  you should use  std  codecvt utf8 utf16 lt  wchar t    include  lt string gt    include  lt codecvt gt   int main          std  string original8   u8            std  wstring original16   L              C  11 format converter     std  wstring convert lt std  codecvt utf8 utf16 lt wchar t gt  gt  convert         convert to UTF8 and std  string     std  string utf8NativeString   convert to bytes original16        std  wstring utf16NativeString   convert from bytes original8        assert utf8NativeString    original8       assert utf16NativeString    original16        return 0

User · Answer

I believe the official way is still to go thorugh codecvt facets  you need some sort of locale-aware translation   as in  resultCode   use facet lt codecvt lt char  wchar t  ConversionState gt   gt  locale     in stateVar  scratchbuffer  scratchbufferEnd  from  to  toLimit  curPtr     or something like that  I don t have working code lying around  But I m not sure how many people these days use that machinery and how many simply ask for pointers to memory and let ICU or some other library handle the gory details

User · Answer

In case anyone else is interested  I needed a class that could be used interchangeably wherever either a string or wstring was expected  The following class convertible string  based on dk123 s solution  can be initialized with either a string  char const   wstring or wchar t const  and can be assigned to by or implicitly converted to either a string or wstring  so can be passed into a functions that take either    class convertible string   public         default ctor     convertible string                  conversion ctors        convertible string std  string const amp  value    value  value             convertible string char const  val array    value  val array             convertible string std  wstring const amp  wvalue    value  ws2s wvalue              convertible string wchar t const  wval array    value  ws2s std  wstring wval array                   assignment operators        convertible string amp  operator  std  string const amp  value                value    value          return  this            convertible string amp  operator  std  wstring const amp  wvalue                value    ws2s wvalue           return  this                implicit conversion operators        operator std  string   const   return value         operator std  wstring   const   return s2ws value      private      std  string value

User · Answer

Instead of including locale and all that fancy stuff  if you know for FACT your string is convertible just do this    include  lt iostream gt   include  lt string gt   using namespace std   int main       wstring w L bla      string result    for char x   w      result    x     cout  lt  lt  result  lt  lt    n       Live example here

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As Cubbi pointed out in one of the comments  std  wstring convert  C  11  provides a neat simple solution  you need to  include  lt locale gt  and  lt codecvt gt     std  wstring string to convert     setup converter using convert type   std  codecvt utf8 lt wchar t gt   std  wstring convert lt convert type  wchar t gt  converter     use converter   to bytes  wstr- gt str   from bytes  str- gt wstr  std  string converted str   converter to bytes  string to convert      I was using a combination of wcstombs and tedious allocation deallocation of memory before I came across this   http   en cppreference com w cpp locale wstring convert  update 2013 11 28   One liners can be stated as so  Thank you Guss for your comment    std  wstring str   std  wstring convert lt std  codecvt utf8 lt wchar t gt  gt    from bytes  some string      Wrapper functions can be stated as so   Thank you ArmanSchwarz for your comment   std  wstring s2ws const std  string amp  str        using convert typeX   std  codecvt utf8 lt wchar t gt       std  wstring convert lt convert typeX  wchar t gt  converterX       return converterX from bytes str      std  string ws2s const std  wstring amp  wstr        using convert typeX   std  codecvt utf8 lt wchar t gt       std  wstring convert lt convert typeX  wchar t gt  converterX       return converterX to bytes wstr       Note  there s some controversy on whether string wstring should be passed in to functions as references or as literals  due to C  11 and compiler updates   I ll leave the decision to the person implementing  but it s worth knowing   Note  I m using std  codecvt utf8 in the above code  but if you re not using UTF-8 you ll need to change that to the appropriate encoding you re using   http   en cppreference com w cpp header codecvt

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This solution is inspired in dk123 s solution  but uses a locale dependent codecvt facet  The result is in locale encoded string instead of UTF-8  if it is not set as locale    std  string w2s const std  wstring  amp var       static std  locale loc         auto  amp facet   std  use facet lt std  codecvt lt wchar t  char  std  mbstate t gt  gt  loc      return std  wstring convert lt std  remove reference lt decltype facet  gt   type  wchar t gt   amp facet  to bytes var      std  wstring s2w const std  string  amp var       static std  locale loc         auto  amp facet   std  use facet lt std  codecvt lt wchar t  char  std  mbstate t gt  gt  loc      return std  wstring convert lt std  remove reference lt decltype facet  gt   type  wchar t gt   amp facet  from bytes var       I was searching for it  but I can t find it  Finally I found that I can get the right facet from std  locale using the std  use facet   function with the right typename  Hope this helps

[c++] How to convert wstring into string?

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