About conversion of characters in C + +

In the engineering properties of VS we often set character set:

In order to support Unicode encoding, it is necessary to convert between multibyte and wide bytes. There are two functions involved:

int  widechartomultibyte(  _in_      UINT    CodePage,  _in_      DWORD   dwFlags,  _in_      lpcwstr lpwidecharstr,  _in_      int     cchwidechar,  _out_opt_ LPSTR   lpmultibytestr,  _in_      int     cbmultibyte,  _in_opt_  LPCSTR  Lpdefaultchar,  _out_opt_ lpbool  lpuseddefaultchar);

And

int  MultiByteToWideChar(  _in_      UINT   CodePage,  _in_      DWORD  dwFlags,  _in_      LPCSTR lpmultibytestr,  _in_      int    cbmultibyte,  _out_opt_ lpwstr Lpwidecharstr,  _in_      int    cchwidechar);

For more information see: Https://msdn.microsoft.com/en-us/library/dd374130%28VS.85%29.aspx and https://msdn.microsoft.com/en-us/ Library/windows/desktop/dd319072%28v=vs.85%29.aspx

These two functions need to specify code pages when they are used, and commonly used code pages are made up of CP_ACP and Cp_utf8 two. The conversion between ANSI and Unicode is achieved using the CP_ACP code page, and the conversion between UTF-8 and Unicode is achieved using the Cp_utf8 code page.

Example:

#include <iostream>#include<string>#include<windows.h>std::wstring Ansitounicode (ConstSTD::string&str); std::stringUnicodetoansi (Conststd::wstring&str); std::wstring Utf8tounicode (ConstSTD::string&str); std::stringUnicodeToUTF8 (Conststd::wstring&str);intMain () {std::stringstr ="Hello world!"; Std::wstring Wstr=Ansitounicode (str); Std::wstring WSTR1= L"Hello World"; STD::stringSTR1 =Unicodetoansi (WSTR1); System ("Pause"); return 0;} Std::wstring Ansitounicode (ConstSTD::string&str) {    intLen =0; Len=str.length (); intUnicodelen =:: MultiByteToWideChar (CP_ACP,//the first time just to get the length converted to wide characters        0, Str.c_str (),-1, NULL,0); wchar_t*Punicode; Punicode=NewWchar_t[unicodelen +1]; memset (Punicode,0, (Unicodelen +1)*sizeof(wchar_t)); :: MultiByteToWideChar (CP_ACP,0, Str.c_str (),-1, (LPWSTR) Punicode, Unicodelen);    std::wstring RT; RT= (wchar_t*) Punicode; DeletePunicode; returnRT;} STD::stringUnicodetoansi (Conststd::wstring&str) {    Char*Pelementtext; intItextlen; //wide char to multi charItextlen =WideCharToMultiByte (CP_ACP,0, Str.c_str (),-1, NULL,0, NULL, NULL); Pelementtext=New Char[Itextlen +1]; memset ((void*) Pelementtext,0,sizeof(Char) * (Itextlen +1)); :: WideCharToMultiByte (CP_ACP,0, Str.c_str (),-1, Pelementtext, Itextlen, NULL, and NULL); STD::stringStrText; StrText=Pelementtext; Delete[] pelementtext; returnStrText;} Std::wstring Utf8tounicode (ConstSTD::string&str) {    intLen =0; Len=str.length (); intUnicodelen =:: MultiByteToWideChar (Cp_utf8,0, Str.c_str (),-1, NULL,0); wchar_t*Punicode; Punicode=NewWchar_t[unicodelen +1]; memset (Punicode,0, (Unicodelen +1)*sizeof(wchar_t)); :: MultiByteToWideChar (Cp_utf8,0, Str.c_str (),-1, (LPWSTR) Punicode, Unicodelen);    std::wstring RT; RT= (wchar_t*) Punicode; DeletePunicode; returnRT;} STD::stringUnicodeToUTF8 (Conststd::wstring&str) {    Char*Pelementtext; intItextlen; //wide char to multi charItextlen =WideCharToMultiByte (Cp_utf8,0, Str.c_str (),-1, NULL,0, NULL, NULL); Pelementtext=New Char[Itextlen +1]; memset ((void*) Pelementtext,0,sizeof(Char) * (Itextlen +1)); :: WideCharToMultiByte (Cp_utf8,0, Str.c_str (),-1, Pelementtext, Itextlen, NULL, and NULL); STD::stringStrText; StrText=Pelementtext; Delete[] pelementtext; returnStrText;}

Results:

There is also a way to use the C function library:

#include <string>#include<iostream>#include<cstdlib>std::stringWs2s (Conststd::wstring&ws) {std::stringCurlocale = setlocale (Lc_all, NULL);//Curlocale = "C";SetLocale (Lc_all,"CHS");//Chinese Area    Constwchar_t* _source =Ws.c_str (); size_t _dsize= Ws.size () +1;//1 Larger than the number of wide characters to convert    Char*_dest =New Char[_dsize]; memset (_dest,0, _dsize);//Initializing bufferssize_t i; wcstombs_s (&I, _dest, _dsize, _source, Ws.size ()); Std::cout<<"I:"<< I <<Std::endl; STD::stringresult =_dest; Delete[]_dest;                               SetLocale (Lc_all, Curlocale.c_str ()); //set back to the original locale    returnresult;} Std::wstring S2ws (ConstSTD::string&s) {std::stringCurllocale =setlocale (Lc_all, NULL); SetLocale (Lc_all,"CHS"); Const Char* _source =S.c_str (); size_t _dsize= S.size () +1; wchar_t* _dest =NewWchar_t[_dsize];    size_t i; mbstowcs_s (&I, _dest, _dsize, _source, S.size ()); std::wstring result=_dest; Delete[] _dest;    SetLocale (Lc_all, Curllocale.c_str ()); returnresult;}intMain () {std::wstring wstr= L"Hello world!"; STD::stringstr =ws2s (WSTR); STD::stringSTR1 ="Hello world!"; Std::wstring WSTR1=S2ws (str); System ("Pause"); return 0;}

Results:

The third method:

#include <string>#include<iostream>std::wstring stringtowstring (ConstSTD::string&str) {std::wstring wstr (str.length (), L' ');    Std::copy (Str.begin (), Str.end (), Wstr.begin ()); returnwstr;}//Copy only low-byte to stringSTD::stringWstringtostring (ConstStd::wstring &wstr) {std::stringSTR (wstr.length (),' ');    Std::copy (Wstr.begin (), Wstr.end (), Str.begin ()); Std::cout<< Str <<Std::endl; returnstr;}intMain () {std::wstring wstr= L"Hello world!"; STD::stringstr =wstringtostring (WSTR); STD::stringSTR1 ="Hello world!"; Std::wstring WSTR1=stringtowstring (str); System ("Pause"); return 0;}

Results:

About conversion of characters in C + +