Windows core Programming Study Notes 1

1. Get the previous error code of the current thread

A: Code getlasterror ()
And formatmessage ()

LPVOID     lpMsgBuffer;DWORD dwRet=FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,NULL,::GetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),reinterpret_cast<LPTSTR>(&lpMsgBuffer),0,NULL);OutputDebugString(reinterpret_cast<LPTSTR>(lpMsgBuffer));LocalFree(lpMsgBuffer);

B: Compiler view $ err, HR

2. When processing strings, try to use string processing functions with _ S.

3. When new allocates string memory:

new TCHAR( nCharacters * sizeof(TCHAR) )

Or customizable macros:

#define chNew(nCharacters) new TCHAR( nCharacters * sizeof(TCHAR) )

4. ANSI to Unicode

General method:

LPWSTR ANSIToUnicode( LPCTSTR lpszSrc){       if (lpszSrc==NULL)        return NULL;    int  unicodeLen = ::MultiByteToWideChar( CP_ACP,        0,        lpszSrc,        -1,        NULL,        0 );      LPWSTR pUnicode = new  wchar_t[unicodeLen+1];      if (pUnicode==NULL)        return NULL;    memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));      ::MultiByteToWideChar( CP_ACP,        0,        lpszSrc,        -1,        (LPWSTR)pUnicode,        unicodeLen );        return  pUnicode;  }

Remember to delete punicode after using ansitounicode;

MFC conversion macro:

#include <atlconv.h>USES_CONVERSION;DoSomething(A2W("SomeString"));      

Pay attention to both a2w and w2a, because the macro-allocated memory is allocated in the function stack. The default stack memory space of the VC compiler is 2 MB. Therefore, do not call these two macros cyclically in a function, and the conversion size cannot exceed 2 MB.

The following conversion functions are available for reference:

1.  ANSI to Unicodewstring ANSIToUnicode( const string& str ){ int  len = 0; len = str.length(); int  unicodeLen = ::MultiByteToWideChar( CP_ACP,            0,            str.c_str(),            -1,            NULL,            0 );   wchar_t *  pUnicode;   pUnicode = new  wchar_t[unicodeLen+1];   memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));   ::MultiByteToWideChar( CP_ACP,         0,         str.c_str(),         -1,         (LPWSTR)pUnicode,         unicodeLen );   wstring  rt;   rt = ( wchar_t* )pUnicode; delete  pUnicode;   return  rt;  }2.  Unicode to ANSIstring UnicodeToANSI( const wstring& str ){ char*     pElementText; int    iTextLen; // wide char to multi char iTextLen = WideCharToMultiByte( CP_ACP,         0,         str.c_str(),         -1,         NULL,         0,NULL,         NULL ); pElementText = new char[iTextLen + 1]; memset( ( void* )pElementText, 0, sizeof( char ) * ( iTextLen + 1 ) ); ::WideCharToMultiByte( CP_ACP,         0,         str.c_str(),         -1,         pElementText,         iTextLen,         NULL,         NULL ); string strText; strText = pElementText; delete[] pElementText; return strText;}3.  UTF-8 to Unicodewstring UTF8ToUnicode( const string& str ){ int  len = 0; len = str.length(); int  unicodeLen = ::MultiByteToWideChar( CP_UTF8,            0,            str.c_str(),            -1,            NULL,            0 );   wchar_t *  pUnicode;   pUnicode = new  wchar_t[unicodeLen+1];   memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));   ::MultiByteToWideChar( CP_UTF8,         0,         str.c_str(),         -1,         (LPWSTR)pUnicode,         unicodeLen );   wstring  rt;   rt = ( wchar_t* )pUnicode; delete  pUnicode;   return  rt;  }4.  Unicode to UTF-8    string UnicodeToUTF8( const wstring& str ){ char*     pElementText; int    iTextLen; // wide char to multi char iTextLen = WideCharToMultiByte( CP_UTF8,         0,         str.c_str(),         -1,         NULL,         0,         NULL,         NULL ); pElementText = new char[iTextLen + 1]; memset( ( void* )pElementText, 0, sizeof( char ) * ( iTextLen + 1 ) ); ::WideCharToMultiByte( CP_UTF8,         0,         str.c_str(),         -1,         pElementText,         iTextLen,         NULL,         NULL ); string strText; strText = pElementText; delete[] pElementText; return strText;}