Databases
StackOverflow2013
Postsdbo
POIs it possible to *safely* return a TCHAR* from a function?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POIs it possible to *safely* return a TCHAR* from a function?
    primarykey
    data
    text
    <p>I've created a function that will convert all the event notification codes to strings. Pretty simple stuff really.</p> <p>I've got a bunch of consts like</p> <pre><code>const _bstr_t DIRECTSHOW_MSG_EC_ACTIVATE("A video window is being activated or deactivated."); const _bstr_t DIRECTSHOW_MSG_EC_BUFFERING_DATA("The graph is buffering data, or has stopped buffering data."); const _bstr_t DIRECTSHOW_MSG_EC_BUILT("Send by the Video Control when a graph has been built. Not forwarded to applications."); .... etc.... </code></pre> <p>and my function</p> <pre><code>TCHAR* GetDirectShowMessageDisplayText( int messageNumber ) { switch( messageNumber ) { case EC_ACTIVATE: return DIRECTSHOW_MSG_EC_ACTIVATE; case EC_BUFFERING_DATA: return DIRECTSHOW_MSG_EC_BUFFERING_DATA; case EC_BUILT: return DIRECTSHOW_MSG_EC_BUILT; ... etc ... </code></pre> <p>No big deal. Took me 5 minutes to throw together.</p> <p>... but I simply don't trust that I've got all the possible values, so I want to have a default to return something like "Unexpected notification code (7410)" if no matches are found.</p> <p>Unfortunately, I can't think of anyway to return a valid pointer, without forcing the caller to delete the string's memory ... which is not only nasty, but also conflicts with the simplicity of the other return values.</p> <p>So I can't think of any way to do this without changing the return value to a parameter where the user passes in a buffer and a string length. Which would make my function look like </p> <pre><code>BOOL GetDirectShowMessageDisplayText( int messageNumber, TCHAR* outBuffer, int bufferLength ) { ... etc ... </code></pre> <p>I really don't want to do that. There must be a better way.</p> <p>Is there?</p> <p>I'm coming back to C++ after a 10 year hiatus, so if it's something obvious, don't discount that I've overlooked it for a reason.</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USJohn MacIntyre
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POIs it possible to *safely* return a TCHAR* from a function?
      1. USPlatinum Azure
      1. VTFavorite
    2. VO
      singulars
      1. POIs it possible to *safely* return a TCHAR* from a function?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POIs it possible to *safely* return a TCHAR* from a function?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIt's not really clear to me if the messages you want to return are static constants, or if they're generated on the fly. If the former, it seems like there is no problem, and you could just return pointers to them directly, as they never need to be deallocated.
      singulars
      1. POIs it possible to *safely* return a TCHAR* from a function?
      1. USjalf
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload