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w_char*和char *转换宽窄字符

w_char*和char*在windows编程过程中进行转换是经常需要的,通常由互联网我们取到都是utf-8编码,到windows应用程序里面却需要用unicode编码。
一开始用stdlib.h 下wcstombs_s和mbstowcs_s的代码实现,发现总是转换失败和出错。
char 转 WCHAR 、wchar_t、LPWSTR ,窄字符转宽字符,C++代码

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//+------------------------------------------------------------------+
//| char to WCHAR 、wchar_t、LPWSTR etc                              |
//+------------------------------------------------------------------+
static char* WStr2CStr(const wchar_t* WStr)
  {
             // 长度设置
              size_t len = wcslen(WStr) + 1;
              size_t converted = 0;
              // 准备转换的对象
              char *CStr;
              CStr=(char*)malloc(len*sizeof(char));
              // 转换
              wcstombs_s(&converted, CStr, len, WStr, _TRUNCATE);
              // 返回
              return CStr;
  }

WCHAR 、wchar_t、LPWSTR转char ,宽字符转窄字符,C++代码

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//+------------------------------------------------------------------+
//| WCHAR 、wchar_t、LPWSTR to char                                  |
//+------------------------------------------------------------------+
static wchar_t* CStr2WStr(const char* CStr)
  {
              // 长度设置
              size_t len = strlen(CStr) + 1;
              size_t converted = 0;
              // 准备转换的对象
              wchar_t *WStr;
              WStr=(wchar_t*)malloc(len*sizeof(wchar_t));
              // 转换
              mbstowcs_s(&converted, WStr, len, CStr, _TRUNCATE);
              // 返回
              return WStr;
  }

后来调查了window系统API,使用MultiByteToWideChar和WideCharToMultiByte可以很好的解决问题。

以下来自微软官方示例代码,使用MultiByteToWideChar和WideCharToMultiByte需要调用两次,一次获取需要设定的缓冲长度,一次转换。效率有点低,但是符合微软的风格。
char 转 WCHAR 、wchar_t、LPWSTR ,窄字符转宽字符,C++代码

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//+------------------------------------------------------------------+
//| char to WCHAR 、wchar_t、LPWSTR etc                              |
//+------------------------------------------------------------------+
static wchar_t * CStr2WStr(const char *cStr)
{
   // MultiByteToWideChar( CP_ACP, 0, chr,
   //     strlen(chr)+1, wchar, size/sizeof(wchar[0]) );
 
        // First: get count of multi-byte string.
    const DWORD cCh = MultiByteToWideChar(CP_ACP,           // Character Page.
                                          0,                // Flag, always be 0.
                                          cStr,             // Multi-byte string.
                                          -1,               // '-1' is to determind length automatically.
                                          NULL,             // 'NULL' means ignore result. This is based
                                                            // on next argument is '0'.
                                          0);               // '0' is to get the count of character needed
                                                            // instead of to translate.
 
    // Second: allocate enough memory to save result in wide character.
    wchar_t* wStr = new wchar_t[cCh];
    ZeroMemory(wStr, cCh * sizeof(wStr[0]));
 
    // Third: Translate it!
    MultiByteToWideChar(CP_ACP,                             // Character Page.
                        0,                                  // Flag, always be 0.
                        cStr,                               // Multi-byte string.
                        -1,                                 // Count of character of string above.
                        wStr,                               // Target wide character buffer.
                        cCh);                               // Count of character of wide character string buffer.
 
        return wStr;
}

WCHAR 、wchar_t、LPWSTR转char ,宽字符转窄字符,C++代码

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//+------------------------------------------------------------------+
//| WCHAR 、wchar_t、LPWSTR to char                                  |
//+------------------------------------------------------------------+
static char* WStr2CStr(const wchar_t *wchar)
{
    //WideCharToMultiByte( CP_ACP, 0, wchar, -1,
    //    chr, length, NULL, NULL );
 
        const DWORD cCh = WideCharToMultiByte(CP_ACP,
                                          0,
                                          wchar,
                                          -1,
                                          NULL,
                                          0,
                                          NULL,             // When the wide character to be traslated
                                                            // is not in code page, proc will use this
                                                            // variable to fill with. We usually set it
                                                            // to NULL.
                                          NULL);            // This variable will save the number of
                                                            // character which can't be tranlated. We
                                                            // usually set it to NULL.
 
    // Second: allocate enough memory to save result.
    char* cStr = new char[cCh];
    ZeroMemory(cStr, cCh * sizeof(cStr[0]));
 
    // Third: Translate it!
    WideCharToMultiByte(CP_ACP,
                        0,
                        wchar,
                        -1,
                        cStr,
                        cCh,
                        NULL,
                        NULL);
 
        return cStr;
}

参考
http://blog.163.com/tianshi_17th/blog/static/4856418920085209414977/
http://www.cnblogs.com/zhwl/archive/2012/11/23/2784282.html
http://www.cnblogs.com/wind-net/archive/2012/10/31/2718329.html

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