VC++互相转码GBK，unicode，utf8

windows平台下微软的库自带了一些api可用于几种编码格式间的互相转码，其实可以用一个iconv开源跨平台的转码库，那个方法更方便且统一。

使用前要引入头文件和命名空间

#include    
#include    
#include    
#include       
using namespace std; 

 

string GBKToUTF8(std::string& strGBK) 
{  
	string strOutUTF8 = "";  
	WCHAR * str1;  
	int n = MultiByteToWideChar(CP_ACP, 0, strGBK.c_str(), -1, NULL, 0);  
	str1 = new WCHAR[n];  
	MultiByteToWideChar(CP_ACP, 0, strGBK.c_str(), -1, str1, n);  
	n = WideCharToMultiByte(CP_UTF8, 0, str1, -1, NULL, 0, NULL, NULL);  
	char * str2 = new char[n];  
	WideCharToMultiByte(CP_UTF8, 0, str1, -1, str2, n, NULL, NULL);  
	strOutUTF8 = str2;  
	delete[]str1;  
	str1 = NULL;  
	delete[]str2;  
	str2 = NULL;  
	return strOutUTF8;
}  

 

 string UTF8ToGBK(const std::string& strUTF8)  
 {  
	 int len = MultiByteToWideChar(CP_UTF8, 0, strUTF8.c_str(), -1, NULL, 0);  
	 unsigned short * wszGBK = new unsigned short[len + 1];  
	 memset(wszGBK, 0, len * 2 + 2);  
	 MultiByteToWideChar(CP_UTF8, 0, (LPCTSTR)strUTF8.c_str(), -1, wszGBK, len);  

	 len = WideCharToMultiByte(CP_ACP, 0, wszGBK, -1, NULL, 0, NULL, NULL);  
	 char *szGBK = new char[len + 1];  
	 memset(szGBK, 0, len + 1);  
	 WideCharToMultiByte(CP_ACP,0, wszGBK, -1, szGBK, len, NULL, NULL);  
	 //strUTF8 = szGBK;   
	 std::string strTemp(szGBK);  
	 delete[]szGBK;  
	 delete[]wszGBK;  
	 return strTemp;  
 }  

 

void UnicodeToUTF8(wchar_t* strW, char szUtf8[])
 {
#ifdef _MSC_VER
	 char* pElementText;
	 int nTextLen;

	 nTextLen =  WideCharToMultiByte(
		 CP_UTF8,            // code page
		 0,            // performance and mapping flags
		 strW,    // wide-character string
		 -1,          // number of chars in string.
		 NULL,     // buffer for new string
		 0,          // size of buffer
		 NULL,     // default for unmappable chars
		 NULL  // set when default char used
		 );
	 pElementText = new char[nTextLen+1];
	 memset((void *)pElementText,0,sizeof(char)* (nTextLen+1));
	 WideCharToMultiByte(
		 CP_UTF8,            // code page
		 0,            // performance and mapping flags
		 strW,    // wide-character string
		 -1,          // number of chars in string.
		 pElementText,     // buffer for new string
		 nTextLen,          // size of buffer
		 NULL,     // default for unmappable chars
		 NULL  // set when default char used
		 );

	 sprintf_s(szUtf8, nTextLen, "%s", pElementText);

	 delete[] pElementText;
	 return ;
#endif
 }

使用举例：

string test("源编码格式需要转成目标编码格式");  
fstream output("test.txt"); //输出到文件  
output << GBKToUTF8(test);  

一般来说utf8用的比较多，推荐都转成utf8