CString转换成const char*



在Visual Studio 2015下，CString直接转换成const char* 有点困难，下面是自己用的一种可行方案：

//得到目录路径

CString mPath=dlg.GetPathName();

//将目录路径转换成绝对路径以便cvLoadImage调用

int m=mPath.GetLength();
for(int index=0;index {
   if(mPath.GetAt(index)=='\\')
{
 mPath.Insert(index,'\\');
 index++;
}

}

//将CString转换成LPCTSTR

LPCTSTR p=mPath.GetBuffer();

/*

将LPCTSTR转换为const char *，因为Unicode的问题，LPCTSTR1、在非UNICODE环境下为 const char * 2、在UNICODE环境下为 const unsigned short *

在情况2时需要借助API函数WideCharToMultiByte

int WideCharToMultiByte(
  UINT CodePage,            // code page
  DWORD dwFlags,            // performance and mapping flags
  LPCWSTR lpWideCharStr,    // wide-character string
  int cchWideChar,          // number of chars in string
  LPSTR lpMultiByteStr,     // buffer for new string
  int cbMultiByte,          // size of buffer
  LPCSTR lpDefaultChar,     // default for unmappable chars
  LPBOOL lpUsedDefaultChar  // set when default char used
);

int WideCharToMultiByte(
  UINT CodePage,            // code page
  DWORD dwFlags,            // performance and mapping flags
  LPCWSTR lpWideCharStr,    // wide-character string
  int cchWideChar,          // number of chars in string
  LPSTR lpMultiByteStr,     // buffer for new string
  int cbMultiByte,          // size of buffer
  LPCSTR lpDefaultChar,     // default for unmappable chars
  LPBOOL lpUsedDefaultChar  // set when default char used
);

*/

DWORD dwMinSize;
dwMinSize=WideCharToMultiByte(CP_ACP,NULL,p,-1,NULL,0,NULL,FALSE);
char * pp=new char[dwMinSize];
WideCharToMultiByte(CP_OEMCP,NULL,p,-1,pp,dwMinSize,NULL,FALSE);

//读取图像
IplImage* ip1=cvLoadImage(pp,-1);