string, CStringA, char*与wstring, CStringW, wchar_t*相互转换

1. char*转换为wchar_t*

char buf[] = "我是韩长鸣haizeiwanghancm";
wchar_t wbuf[100];

1.1. C的方式：最可移植的方式

1.1.1. mbstowcs

setlocale(LC_CTYPE, "");
mbstowcs(wbuf, buf, sizeof(buf));

1.1.2. swprintf

setlocale(LC_CTYPE, "");
swprintf(wbuf, L"%S", buf);


1.2. Windows平台的方式

1.2.1. wsprintf

wsprintf(wbuf, L"%S", buf);

1.2.2. MultiByteToWideChar

//返回需要的多字节数目(包括结尾'')
    int len = MultiByteToWideChar(
        CP_ACP,      //多字节相关的代码页
        0,           //额外控制，影响变音符号，一般设为0
        buf,         //char缓冲区
        -1,          //char字符个数，-1函数自动判断长度
        NULL,        //wchar_t缓冲区
        0);          //wchar_t缓冲区最大字节数，传入0：不执行转换，返回需要的宽字节数目(包括结尾'')

    wchar_t *wbuf2 = new wchar_t[len * sizeof(wchar_t)];
    if (wbuf == nullptr) {
        return 0;
    }

    MultiByteToWideChar(CP_ACP, 0, buf, -1, wbuf2, len);

1.3. ATL，MFC可用的方式

1.3.1. A2W

  USES_CONVERSION;
  MessageBoxW(nullptr, A2W(buf), nullptr, 0);

1.3.2. CStringW

CStringW str = buf;

//这里存在一个operator const wchar_t*的操作符重载
MessageBox(nullptr, str, nullptr, 0);

2. wchar_t*转char*相似的过程，看最后的程序

3. 附赠： CStringW, CStringA, wstring，string, wchar_t*, char*的相互转换

//7. string转wchar_t*
    string str1 = "string方式, jsfoej韩长鸣fiok";
    wstring ch(str1.size(), 0);
    setlocale(LC_CTYPE, "");
    mbstowcs(&ch[0], str1.c_str(), str1.size());
    MessageBoxW(nullptr, ch.c_str(), nullptr, 0);

    //8. CStringA转wchar_t*
    CStringA CStr = "CStringA方式jsofj韩长鸣eof";
    CStringW WStr = CStr;
    MessageBox(nullptr, WStr, nullptr, 0);

    //9. CStringA转string,直接赋值
    CStringA Astr(L"韩长鸣sjfo");
    string s = Astr;
    cout << s << endl;

    //10. string转CStringA, CString = string.c_str();

    //11. CStringA转wstring: CStringW = CStringA; wstring = CStringW;

    //12. string转CStringW: CStringA = string.cstr(); CStringW = CStringA;

//7. wstring转char*
    wstring str1 = L"wstring方式, jsfoej韩长鸣fiok";
    string ch(str1.size(), 0);
    setlocale(LC_CTYPE, "");
    wcstombs(&ch[0], str1.c_str(), str1.size());
    MessageBoxA(nullptr, ch.c_str(), nullptr, 0);

    //8. CStringW转char*
    CStringW CStr = "CStringW方式jsofj韩长鸣eof";
    CStringA AStr = CStr;
    MessageBoxA(nullptr, AStr, nullptr, 0);

    //9. CStringW转wstring,直接赋值
    CStringW wstr(L"韩长鸣sjfo");
    wstring ws = wstr;
    wcout << ws << endl;

    //10. wstring转CStringW, CStringW = wstring.c_str();

    //11. CStringW转string: CStringA = CStringW; string = CStringA;

    //12. wstring转CStringA: CStringW = wstring.cstr(); CStringA = CStringW;

//char*转wchar_t*

  1 #include <Windows.h>    //for wsprintf, MultiByteToWideChar，WideCharToMultiByte
  2 #include <cstdio>       //for swprintf 
  3 #include <atlconv.h>    //for A2W(),W2A()
  4 #include <atlstr.h>     //for CString
  5 #include <locale>
  6 #include <string>
  7 #include <iostream>
  8 
  9 using std::cout;
 10 using std::wcout;
 11 using std::endl;
 12 using std::string;
 13 using std::wstring;
 14 using std::locale;
 15 
 16 #pragma warning(disable : 4996)
 17 
 18 int main(void)
 19 {
 20     char buf[] = "我是韩长鸣haizeiwanghancm";
 21     wchar_t wbuf[100];
 22 
 23     //1. CRT的swprintf()函数
 24     MessageBoxW(NULL, L"swprintf", nullptr, 0);
 25     //C方式的必须设置本地化locale
 26     //locale old_loc = locale::global(locale(""));
 27     setlocale(LC_CTYPE, "");
 28     swprintf(wbuf, L"%S", buf);
 29     MessageBoxW(NULL, wbuf, NULL, 0);
 30     //locale::global(old_loc);
 31 
 32     //2. windows的wsprintf()函数
 33     //汉字：wsprintf没问题
 34     //%S: 宽字符
 35     MessageBoxW(NULL, L"wsprintf", nullptr, 0);
 36     wsprintf(wbuf, L"%S", buf);
 37     MessageBoxW(NULL, wbuf, NULL, 0);
 38     // 也直接使用带A的函数，
 39     //在内部它会使用多字节转换函数将字符串传换为wchar_t*
 40     MessageBoxA(NULL, buf, NULL, 0);
 41 
 42     
 43 
 44     //3. Windows的MultiByteToWideChar(): 都没问题
 45 
 46     MessageBoxW(NULL, L"MultiByteToWideChar函数", nullptr, 0);
 47 
 48     //返回需要的多字节数目(包括结尾'')
 49     int len = MultiByteToWideChar(
 50         CP_ACP,      //多字节相关的代码页
 51         0,           //额外控制，影响变音符号，一般设为0
 52         buf,         //char缓冲区
 53         -1,          //char字符个数，-1函数自动判断长度
 54         NULL,        //wchar_t缓冲区
 55         0);          //wchar_t缓冲区最大字节数，传入0：不执行转换，返回需要的宽字节数目(包括结尾'')
 56 
 57     wchar_t *wbuf2 = new wchar_t[len * sizeof(wchar_t)];
 58     if (wbuf == nullptr) {
 59         return 0;
 60     }
 61 
 62     MultiByteToWideChar(CP_ACP, 0, buf, -1, wbuf2, len);
 63     MessageBoxW(NULL, wbuf2, NULL, 0);
 64     delete[] wbuf2;
 65 
 66     //4. CTR的mbstowcs()函数
 67     MessageBoxW(NULL, L"mbstowcs函数", nullptr, 0);
 68     setlocale(LC_CTYPE, "");
 69     //locale old_loc = locale::global(locale(""));
 70     mbstowcs(wbuf, buf, sizeof(buf));
 71     //locale::global(old_loc);
 72     MessageBoxW(nullptr, wbuf, nullptr, 0);
 73 
 74     //5. ATL的A2W在MFC中也可以
 75     MessageBoxW(nullptr, L"A2W()", nullptr, 0);
 76     USES_CONVERSION;
 77     MessageBoxW(nullptr, A2W(buf), nullptr, 0);
 78 
 79     //6. ATL的CStringW
 80     MessageBoxW(nullptr, L"CString方式", nullptr, 0);
 81     CStringW str = buf;
 82     MessageBox(nullptr, str, nullptr, 0);
 83 
 84     //7. string转wchar_t*
 85     string str1 = "string方式, jsfoej韩长鸣fiok";
 86     wstring ch(str1.size(), 0);
 87     setlocale(LC_CTYPE, "");
 88     mbstowcs(&ch[0], str1.c_str(), str1.size());
 89     MessageBoxW(nullptr, ch.c_str(), nullptr, 0);
 90 
 91     //8. CStringA转wchar_t*
 92     CStringA CStr = "CStringA方式jsofj韩长鸣eof";
 93     CStringW WStr = CStr;
 94     MessageBox(nullptr, WStr, nullptr, 0);
 95 
 96     //9. CStringA转string,直接赋值
 97     CStringA Astr(L"韩长鸣sjfo");
 98     string s = Astr;
 99     cout << s << endl;
100 
101     //10. string转CStringA, CString = string.c_str();
102 
103     //11. CStringA转wstring: CStringW = CStringA; wstring = CStringW;
104 
105     //12. string转CStringW: CStringA = string.cstr(); CStringW = CStringA;
106 
107     return 0;
108 }

//wchar_t*转char*

#include <cstdio>       //for swprintf，sprintf 
#include <cstdlib>      //for mbstowidechar, widechartombs函数
#include <Windows.h>    //for wsprintf, MultiByteToWideChar，WideCharToMultiByte
#include <atlconv.h>    //for A2W(),W2A()
#include <atlstr.h>     //for CString
#include <iostream>     //for std::locale
#include <string>
#include <locale.h>

using std::cout;
using std::wcout;
using std::endl;
using std::string;
using std::wstring;

#pragma warning(disable : 4996)

int main(void)
{
    wchar_t wbuf[] = L"我是韩长鸣haizeiwanghancm";
    char buf[100];
    //1. CRT的sprintf()函数

    MessageBoxW(NULL, L"sprintf函数", nullptr, 0);
    //使用系统locale
    setlocale(LC_CTYPE, "");
    //locale oldlocale = locale::global(locale(""));
    sprintf(buf, "%S", wbuf);
    MessageBoxA(NULL, buf, NULL, 0);
    //locale::global(oldlocale);

    //2. windows的wsprintfA()
    //%S: 宽字符
    MessageBoxW(NULL, L"wsprintfA函数", nullptr, 0);
    wsprintfA(buf, "%S", wbuf);
    MessageBoxA(NULL, buf, NULL, 0);
    // 也直接使用带W的函数，
    MessageBoxW(NULL, wbuf, NULL, 0);

    //3. Windows的WideCharToMultiByte(): 都没问题

    MessageBoxW(NULL, L"WideCharToMultiByte()函数", nullptr, 0);

    //返回需要的字节数目(包括结尾'')
    int len = WideCharToMultiByte(
        CP_ACP,      //多字节相关的代码页
        0,           //额外控制，影响变音符号，一般设为0
        wbuf,         //wchar缓冲区
        -1,          //wchar字符个数，-1函数自动判断长度
        NULL,        //char缓冲区
        0,           //char缓冲区最大字节数，传入0：不执行转换，返回需要的宽字节数目(包括结尾'')
        nullptr,     //遇到不能转换的字符时的替换字符，nullptr:代表使用系统默认字符，通常？
        nullptr      //表明是否转换成功：TRUE:有不能转换的字符，FALSE：成功
        );         

    char *buf2 = new char[len];
    if (wbuf == nullptr) {
    return 0;
    }

    WideCharToMultiByte(CP_ACP, 0, wbuf, -1, buf2, len, nullptr, nullptr);
    MessageBoxA(NULL, buf2, NULL, 0);
    delete[] buf2;

    //4. CTR的mbstowcs()函数
    MessageBoxW(NULL, L"wcstombs函数", nullptr, 0);
    setlocale(LC_CTYPE, "");
    //locale old_loc = locale::global(locale(""));
    wcstombs(buf, wbuf, sizeof(wbuf));
    MessageBoxA(nullptr, buf, nullptr, 0);
    //locale::global(old_loc);

    //5. ATL的A2W在MFC中也可以
    MessageBoxW(nullptr, L"W2A()", nullptr, 0);
    USES_CONVERSION;
    MessageBoxA(nullptr, W2A(wbuf), nullptr, 0);

    //6. ATL的CStringA, CStringA再operator const char*
    MessageBoxW(nullptr, L"CString方式", nullptr, 0);
    CStringA str = wbuf;
    MessageBoxA(nullptr, str, nullptr, 0);

    //7. wstring转char*
    wstring str1 = L"wstring方式, jsfoej韩长鸣fiok";
    string ch(str1.size(), 0);
    setlocale(LC_CTYPE, "");
    wcstombs(&ch[0], str1.c_str(), str1.size());
    MessageBoxA(nullptr, ch.c_str(), nullptr, 0);

    //8. CStringW转char*
    CStringW CStr = "CStringW方式jsofj韩长鸣eof";
    CStringA AStr = CStr;
    MessageBoxA(nullptr, AStr, nullptr, 0);

    //9. CStringW转wstring,直接赋值
    CStringW wstr(L"韩长鸣sjfo");
    wstring ws = wstr;
    wcout << ws << endl;

    //10. wstring转CStringW, CStringW = wstring.c_str();

    //11. CStringW转string: CStringA = CStringW; string = CStringA;

    //12. wstring转CStringA: CStringW = wstring.cstr(); CStringA = CStringW;

    return 0;
}
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原文地址：https://www.cnblogs.com/hancm/p/4123652.html