DevelopersVoice.com

Q: How can I start a process ?
A: There are several ways to start a process:

• 'system()' family (C run-time library - ANSI ('system()') or Win NT ('_wsystem()'))
• '_exec()' family (C run-time library - Win 95, Win NT)
• '_spawn()' family (C run-time library - Win 95, Win NT)
• 'WinExec()' (Win32 API)
• 'ShellExecute()' (Shell API)
• 'ShellExecuteEx()' (Shell API)
• 'CreateProcess()' (Win32 API)
• 'CreateProcessAsUser()' (Win32 API)
• 'CreateProcessWithLogonW()' (Win32 API)

Most common are 'ShellExecute()', ShellExecuteEx()' and 'CreateProcess()'. Note that 'WinExec()' is provided only for compatibility with 16-bit Windows and should not be used any longer. The following examples will show how to display the text file 'c:\example.txt' in 'notepad.exe' using these three functions...

1. 'ShellExecute()'
   
   HINSTANCE hInst = ShellExecute(0,
   "open", // Operation to perform
   "c:\\windows\\notepad.exe", // Application name
   "c:\\example.txt", // Additional parameters
   0, // Default directory
   SW_SHOW);
   if(reinterpret_cast<int>(hInst) <= 32)
   {
   // Could not start application
   switch(reinterpret_cast<int>(hInst))
   {
   case 0:
   // The operating system is out of memory or resources.
   break;
   case ERROR_FILE_NOT_FOUND:
   // The specified file was not found.
   break;
   case ERROR_PATH_NOT_FOUND:
   // The specified path was not found.
   break;
   case ERROR_BAD_FORMAT:
   // The .exe file is invalid (non-Microsoft Win32 .exe or error in .exe image).
   break;
   case SE_ERR_ACCESSDENIED:
   // The operating system denied access to the specified file.
   break;
   case SE_ERR_ASSOCINCOMPLETE:
   // The file name association is incomplete or invalid.
   break;
   case SE_ERR_DDEBUSY:
   // The Dynamic Data Exchange (DDE) transaction could not be completed because
   // other DDE transactions were being processed.
   break;
   case SE_ERR_DDEFAIL:
   // The DDE transaction failed.
   break;
   case SE_ERR_DDETIMEOUT:
   // The DDE transaction could not be completed because the request timed out.
   break;
   case SE_ERR_DLLNOTFOUND:
   // The specified dynamic-link library (DLL) was not found.
   
   case SE_ERR_FNF:
   // The specified file was not found.
   break;
   case SE_ERR_NOASSOC:
   // There is no application associated with the given file name extension.
   // This error will also be returned if you attempt to print a file that is
   // not printable.
   break;
   case SE_ERR_OOM:
   // There was not enough memory to complete the operation.
   break;
   case SE_ERR_PNF:
   // The specified path was not found.
   break;
   case SE_ERR_SHARE:
   // A sharing violation occurred.
   break;
   }
   }
2. 'ShellExecuteEx()'
   
   SHELLEXECUTEINFO ExecuteInfo;
   memset(&ExecuteInfo, 0, sizeof(ExecuteInfo));
   ExecuteInfo.cbSize = sizeof(ExecuteInfo);
   ExecuteInfo.fMask = 0;
   ExecuteInfo.hwnd = 0;
   ExecuteInfo.lpVerb = "open"; // Operation to perform
   ExecuteInfo.lpFile = "c:\\windows\\notepad.exe"; // Application name
   ExecuteInfo.lpParameters = "c:\\example.txt"; // Additional parameters
   ExecuteInfo.lpDirectory = 0; // Default directory
   ExecuteInfo.nShow = SW_SHOW;
   ExecuteInfo.hInstApp = 0;
   if(ShellExecuteEx(&ExecuteInfo) == FALSE)
   // Could not start application -> call 'GetLastError()'
3. 'CreateProcess()'
   
   STARTUPINFO siStartupInfo;
   PROCESS_INFORMATION piProcessInfo;
   memset(&siStartupInfo, 0, sizeof(siStartupInfo));
   memset(&piProcessInfo, 0, sizeof(piProcessInfo));
   siStartupInfo.cb = sizeof(siStartupInfo);
   if(CreateProcess("c:\\windows\\notepad.exe", // Application name
   " example.txt", // Application arguments
   0,
   0,
   FALSE,
   CREATE_DEFAULT_ERROR_MODE,
   0,
   0, // Working directory
   &siStartupInfo,
   &piProcessInfo) == FALSE)
   // Could not start application -> call 'GetLastError()'
   In general 'ShellExecuteEx()' and even 'CreateProcess()' provides more controlling features of the application to start and its termination.

Note: Most of the material in this article is taken from codeguru.com