Codex API: Shell


The RegisterCodexApplication function sets an application as the default handler for Codex archives opened in Windows Explorer.


BOOL RegisterCodexApplication(
    LPCTSTR lpName,             // application name
    LPCTSTR lpEXE,              // executable path
    LPCTSTR lpDDE               // DDE conversation topic



[in] Pointer to a null-terminated string that specifies the name of the application.


[in] Pointer to a null-terminated string that specifies the full path of the application executable.


[in] Pointer to a null-terminated string that specifies the DDE conversation topic if the application supports DDE.

DDE allows an application to open multiple documents selected from the shell within a single running instance. See the Windows Platform SDK for more information.

Specify NULL in this parameter to indicate your application does not support DDE.

Return Values

If the function succeeds, the return value is TRUE.

If the function fails, the return value is FALSE. Check your access rights to the registry.


If a single Codex archive is selected and opened in Windows Explorer, an application registered with RegisterCodexApplication will launch, having the archive filename as its first command line parameter.

If multiple Codex archives are selected and opened in Windows Explorer:

  • If DDE was used, Windows Explorer will start a DDE conversation with the topic indicated in the lpDDE parameter and send the application information on each of the selected archives.

  • If DDE was not used, Windows Explorer will start separate copies of the application for each selected archive, having the respective archive filenames as separate command line parameters for each instance of the application.

RegisterCodexApplication associates an application only with archives already assigned to Codex. For more information on assigning archives to Codex, see the CheckCodexAssociations, EditCodexAssociations, and ForceCodexAssociations functions.


Windows NT/2000/XP: Requires Windows NT 4.0 SP4 or later.
Windows 95/98/Me:
Requires Windows 98 (or Windows 95 with DCOM 1.2).
Declared in mCodexAPI.h.
Use mCodexAPI.dll.

See Also

Codex API Overview, Codex API Functions, CheckCodexAssociations, EditCodexAssociations, ForceCodexAssociations