www.pudn.com > VC6GetCommPort.rar > enumser.cpp, change:1999-12-12,size:3251b

#include "stdafx.h" 
#include "enumser.h" 
///////////////////////////// Statics / Locals //////////////////////////////// 
#ifdef _DEBUG 
#undef THIS_FILE 
#define new DEBUG_NEW 
static char BASED_CODE THIS_FILE[] = __FILE__; 
///////////////////////////// Implementation ////////////////////////////////// 
void EnumerateSerialPorts(CUIntArray& ports) 
  //Make sure we clear out any elements which may already be in the array 
  //Determine what OS we are running on 
  osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO); 
  BOOL bGetVer = GetVersionEx(&osvi); 
  //On NT use the QueryDosDevice API 
  if (bGetVer && (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT)) 
    //Use QueryDosDevice to look for all devices of the form COMx. This is a better 
    //solution as it means that no ports have to be opened at all. 
    TCHAR szDevices[65535]; 
    DWORD dwChars = QueryDosDevice(NULL, szDevices, 65535); 
    if (dwChars) 
      int i=0; 
      for (;;) 
        //Get the current device name 
        TCHAR* pszCurrentDevice = &szDevices[i]; 
        //If it looks like "COMX" then 
        //add it to the array which will be returned 
        int nLen = _tcslen(pszCurrentDevice); 
        if (nLen > 3 && _tcsnicmp(pszCurrentDevice, _T("COM"), 3) == 0) 
          //Work out the port number 
          int nPort = _ttoi(&pszCurrentDevice[3]); 
        // Go to next NULL character 
        while(szDevices[i] != _T('\0')) 
        // Bump pointer to the next string 
        // The list is double-NULL terminated, so if the character is 
        // now NULL, we're at the end 
        if (szDevices[i] == _T('\0')) 
      TRACE(_T("Failed in call to QueryDosDevice, GetLastError:%d\n"), GetLastError()); 
    //On 95/98 open up each port to determine their existence 
    //Up to 255 COM ports are supported so we iterate through all of them seeing 
    //if we can open them or if we fail to open them, get an access denied or general error error. 
    //Both of these cases indicate that there is a COM port at that number.  
    for (UINT i=1; i<256; i++) 
      //Form the Raw device name 
      CString sPort; 
      sPort.Format(_T("\\\\.\\COM%d"), i); 
      //Try to open the port 
      BOOL bSuccess = FALSE; 
      HANDLE hPort = ::CreateFile(sPort, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0); 
      if (hPort == INVALID_HANDLE_VALUE) 
        DWORD dwError = GetLastError(); 
        //Check to see if the error was because some other app had the port open or a general failure 
        if (dwError == ERROR_ACCESS_DENIED || dwError == ERROR_GEN_FAILURE) 
          bSuccess = TRUE; 
        //The port was opened successfully 
        bSuccess = TRUE; 
        //Don't forget to close the port, since we are going to do nothing with it anyway 
      //Add the port number to the array which will be returned 
      if (bSuccess)