1. //UTF8轉ANSI
2. void UTF8toANSI(CString &strUTF8)  
3. {  
4.     //獲取轉換為多位元組後需要的緩衝區大小，建立多位元組緩衝區
5.     UINT nLen = MultiByteToWideChar(CP_UTF8,NULL,strUTF8,-1,NULL,NULL);  
6.     WCHAR *wszBuffer = newWCHAR[nLen+1];  
7.     nLen = MultiByteToWideChar(CP_UTF8,NULL,strUTF8,-1,wszBuffer,nLen);  
8.     wszBuffer[nLen] = 0;  
9.     nLen = WideCharToMultiByte(936,NULL,wszBuffer,-1,NULL,NULL,NULL,NULL);  
10.     CHAR *szBuffer = newCHAR[nLen+1];  
11.     nLen = WideCharToMultiByte(936,NULL,wszBuffer,-1,szBuffer,nLen,NULL,NULL);  
12.     szBuffer[nLen] = 0;  
13.     strUTF8 = szBuffer;  
14.     //清理記憶體
15.     delete []szBuffer;  
16.     delete []wszBuffer;  
17. }  

//UTF8轉ANSI
void UTF8toANSI(CString &strUTF8)
{
    //獲取轉換為多位元組後需要的緩衝區大小，建立多位元組緩衝區
    UINT nLen = MultiByteToWideChar(CP_UTF8,NULL,strUTF8,-1,NULL,NULL);
    WCHAR *wszBuffer = new WCHAR[nLen+1];
    nLen = MultiByteToWideChar(CP_UTF8,NULL,strUTF8,-1,wszBuffer,nLen);
    wszBuffer[nLen] = 0;

    nLen = WideCharToMultiByte(936,NULL,wszBuffer,-1,NULL,NULL,NULL,NULL);
    CHAR *szBuffer = new CHAR[nLen+1];
    nLen = WideCharToMultiByte(936,NULL,wszBuffer,-1,szBuffer,nLen,NULL,NULL);
    szBuffer[nLen] = 0;

    strUTF8 = szBuffer;
    //清理記憶體
    delete []szBuffer;
    delete []wszBuffer;
}
 

1. //ANSI轉UTF8
2. void ANSItoUTF8(CString &strAnsi)  
3. {  
4.     //獲取轉換為寬位元組後需要的緩衝區大小，建立寬位元組緩衝區，936為簡體中文GB2312內碼表
5.     UINT nLen = MultiByteToWideChar(936,NULL,strAnsi,-1,NULL,NULL);  
6.     WCHAR *wszBuffer = newWCHAR[nLen+1];  
7.     nLen = MultiByteToWideChar(936,NULL,strAnsi,-1,wszBuffer,nLen);  
8.     wszBuffer[nLen] = 0;  
9.     //獲取轉為UTF8多位元組後需要的緩衝區大小，建立多位元組緩衝區
10.     nLen = WideCharToMultiByte(CP_UTF8,NULL,wszBuffer,-1,NULL,NULL,NULL,NULL);  
11.     CHAR *szBuffer = newCHAR[nLen+1];  
12.     nLen = WideCharToMultiByte(CP_UTF8,NULL,wszBuffer,-1,szBuffer,nLen,NULL,NULL);  
13.     szBuffer[nLen] = 0;  
14.     strAnsi = szBuffer;  
15.     //記憶體清理
16.     delete []wszBuffer;  
17.     delete []szBuffer;  
18. }  

//ANSI轉UTF8
void ANSItoUTF8(CString &strAnsi)
{
    //獲取轉換為寬位元組後需要的緩衝區大小，建立寬位元組緩衝區，936為簡體中文GB2312內碼表
    UINT nLen = MultiByteToWideChar(936,NULL,strAnsi,-1,NULL,NULL);
    WCHAR *wszBuffer = new WCHAR[nLen+1];
    nLen = MultiByteToWideChar(936,NULL,strAnsi,-1,wszBuffer,nLen);
    wszBuffer[nLen] = 0;
    //獲取轉為UTF8多位元組後需要的緩衝區大小，建立多位元組緩衝區
    nLen = WideCharToMultiByte(CP_UTF8,NULL,wszBuffer,-1,NULL,NULL,NULL,NULL);
    CHAR *szBuffer = new CHAR[nLen+1];
    nLen = WideCharToMultiByte(CP_UTF8,NULL,wszBuffer,-1,szBuffer,nLen,NULL,NULL);
    szBuffer[nLen] = 0;

    strAnsi = szBuffer;
    //記憶體清理
    delete []wszBuffer;
    delete []szBuffer;
}

自己改的c版本，測試可用：

static void UTF8toANSI(char *strUTF8,char*out_ansi)
{
//獲取轉換為多位元組後需要的緩衝區大小，建立多位元組緩衝區
UINT nLen = MultiByteToWideChar(CP_UTF8, 0, strUTF8, -1, NULL, 0);
WCHAR wszBuffer = (WCHAR)malloc((nLen+1)*sizeof(WCHAR));
nLen = MultiByteToWideChar(CP_UTF8, 0, strUTF8, -1, wszBuffer, nLen);
wszBuffer[nLen] = 0;

nLen = WideCharToMultiByte(936, 0, wszBuffer, -1, NULL, 0, NULL, NULL);
nLen = WideCharToMultiByte(936, 0, wszBuffer, -1, out_ansi, nLen, NULL, NULL);
out_ansi[nLen] = 0;

}