The ShellExecute function opens or prints a specified file. The file can be an executable file or a document file. See ShellExecuteEx also. 

HINSTANCE ShellExecute(

    HWND  hwnd,			// handle to parent window
    LPCTSTR  lpOperation,	// pointer to string that specifies operation to perform
    LPCTSTR  lpFile,		// pointer to filename string
    LPTSTR  lpParameters,	// pointer to string that specifies executable-file parameters 
    LPCTSTR  lpDirectory,	// pointer to string that specifies default directory
    INT  nShowCmd 		// whether file is shown when opened
   );	
Parameters

hwnd		Specifies a parent window. This window receives any message boxes that an application produces. For example, an application may report an error by producing a message box.  

lpOperation	Pointer to a null-terminated string that specifies the operation to perform. The following operation strings are valid:

String		Meaning
		"open"	The function opens the file specified by lpFile. The file can be an executable file or a document file.
		"print"	The function prints the file specified by lpFile. The file should be a document file. If the file is an executable file, the function opens the file, as if "open" had been specified.
		The lpOperation parameter can be NULL. In that case, the function opens the file specified by lpFile. 

lpFile		Pointer to a null-terminated string that specifies the file to open or print. The function can open an executable file or a document file. The function can print a document file. 

lpParameters	If lpFile specifies an executable file, lpParameters is a pointer to a null-terminated string that specifies parameters to be passed to the application.
		If lpFile specifies a document file, lpParameters should be NULL. 

lpDirectory	Pointer to a null-terminated string that specifies the default directory. 
nShowCmd	If lpFile specifies an executable file, nShowCmd specifies how the application is to be shown when it is opened.  This parameter can be one of the following values: 

Value	Meaning
SW_HIDE	Hides the window and activates another window.
SW_MAXIMIZE	Maximizes the specified window.
SW_MINIMIZE	Minimizes the specified window and activates the next top-level window in the Z order.
SW_RESTORE	Activates and displays the window. If the window is minimized or maximized, Windows restores it to its original size and position. An application should specify this flag when restoring a minimized window.
SW_SHOW	Activates the window and displays it in its current size and position. 
SW_SHOWDEFAULT	Sets the show state based on the SW_ flag specified in the STARTUPINFO structure passed to the CreateProcess function by the program that started the application. An application should call ShowWindow with this flag to set the initial show state of its main window.
SW_SHOWMAXIMIZED	Activates the window and displays it as a maximized window.
SW_SHOWMINIMIZED	Activates the window and displays it as a minimized window.
SW_SHOWMINNOACTIVE	Displays the window as a minimized window. The active window remains active.
SW_SHOWNA	Displays the window in its current state. The active window remains active.
SW_SHOWNOACTIVATE	Displays a window in its most recent size and position. The active window remains active.
SW_SHOWNORMAL	Activates and displays a window. If the window is minimized or maximized, Windows restores it to its original size and position. An application should specify this flag when displaying the window for the first time.
If lpFile specifies a document file, nShowCmd should be zero. 

Return Value

If the function succeeds, the return value is the instance handle of the application that was run, or the handle of a dynamic data exchange (DDE) server application.
If the function fails, the return value is an error value that is less than or equal to 32. The following table lists these error values:

Value	Meaning
0	The operating system is out of memory or resources.
ERROR_FILE_NOT_FOUND	The specified file was not found.
ERROR_PATH_NOT_FOUND	The specified path was not found.
ERROR_BAD_FORMAT	The .EXE file is invalid (non-Win32 .EXE or error in .EXE image).
SE_ERR_ACCESSDENIED	Windows 95 only: The operating system denied access to the specified file. 
SE_ERR_ASSOCINCOMPLETE	The filename association is incomplete or invalid.
SE_ERR_DDEBUSY	The DDE transaction could not be completed because other DDE transactions were being processed.
SE_ERR_DDEFAIL	The DDE transaction failed.
SE_ERR_DDETIMEOUT	The DDE transaction could not be completed because the request timed out.
SE_ERR_DLLNOTFOUND	Windows 95 only: The specified dynamic-link library was not found. 
SE_ERR_FNF	Windows 95 only: The specified file was not found. 
SE_ERR_NOASSOC	There is no application associated with the given filename extension.
SE_ERR_OOM	Windows 95 only: There was not enough memory to complete the operation.
SE_ERR_PNF	Windows 95 only: The specified path was not found.
SE_ERR_SHARE	A sharing violation occurred.
Remarks

The file specified by the lpFile parameter can be a document file or an executable file. If the file is a document file, the ShellExecute function opens or prints it, depending on the value of the lpOperation parameter. If the file is an executable file, the ShellExecute function opens it, even if lpOperation specifies printing. 
Windows 95: You can use ShellExecute to open or explore a Windows 95 folder. To open a folder, use either of the following calls:

ShellExecute(handle, NULL, "path_to_folder", NULL, NULL, SW_SHOWNORMAL);

or

ShellExecute(handle, "open", "path_to_folder", NULL, NULL, SW_SHOWNORMAL);

To explore a folder, use the following call:

ShellExecute(handle, "explore", "path_to_folder", NULL, NULL, SW_SHOWNORMAL);

If lpOperation is NULL, the function opens the file specified by lpFile. If lpOperation is "open" or "explore", the function will force a open window or explorer.