{"id":23,"date":"2013-07-18T08:36:34","date_gmt":"2013-07-18T08:36:34","guid":{"rendered":"https:\/\/praveenkatiyar.wordpress.com\/?p=23"},"modified":"2013-07-18T08:36:34","modified_gmt":"2013-07-18T08:36:34","slug":"packing-a-array-of-strings-inside-a-variant-vc-6-0-series-2-of-n","status":"publish","type":"post","link":"https:\/\/praveenkatiyar.in\/blog\/index.php\/2013\/07\/18\/packing-a-array-of-strings-inside-a-variant-vc-6-0-series-2-of-n\/","title":{"rendered":"Packing a array inside a VARIANT (VC++ 6.0) (Series 2 of N)"},"content":{"rendered":"

This is the second post about variant, in this post I I am going to explain, how an array of strings can be packed inside a VARIANT variable.<\/p>\n

Packing  a array of string inside a Variant<\/h3>\n

int  PackVariantWithStringArray(short nCnt, VARIANT * pVar )
{
    USES_CONVERSION ;<\/strong><\/font><\/p>\n

    \/\/Initialize the VARIANT (Type is SAFEARRAY of BSTRs)
    VariantInit(pVar);
    pVar->vt = VT_ARRAY | VT_BSTR;<\/strong><\/font><\/p>\n

    \/\/ Define a safe array of nCnt Item and Starting index as 0
    SAFEARRAYBOUND safeBounds = { nCnt, 0};
   
    \/\/Create the Safe Array passing it the bounds
    SAFEARRAY* pSafeArray = SafeArrayCreate(VT_BSTR, 1, &safeBounds);<\/strong><\/font><\/p>\n

    \/\/Get a pointer, actually increments the array’s lock count)
    BSTR* bstrArray = NULL;
    SafeArrayAccessData(pSafeArray, (void**)&bstrArray);
    for ( int i = 0 ; i < nCnt ; i++ )
    {
        CString strTmp ;
        strTmp.Format ( _T("This is Item %2d"), i );
        bstrArray [i] = strTmp.AllocSysString () ;
    } <\/strong><\/font><\/p>\n

    \/\/done wth populating, Decrement the array’s lock count
    SafeArrayUnaccessData(pSafeArray);<\/strong><\/font><\/p>\n

    \/\/Assign our VARIANT out param with the array   
    pVar->parray = pSafeArray ;
    return nCnt ;
}<\/strong><\/font><\/p>\n

<\/strong><\/font><\/p>\n

as it can be seen from the above code, it involves following steps.<\/p>\n

    \n
  1. Allocating the desired temporary buffer space to hold the array of bytes, and filling that array with values one need to return. <\/li>\n
  2. creating a safe array of the desired (VT_BSTR)<\/font><\/strong> type. <\/li>\n
  3. copying the temporary buffer to the safe array of the variant. <\/li>\n
  4. free the memory allocated for temporary buffer. (avoid memory leaks). <\/li>\n<\/ol>\n

    Fetching a array of strings from a variant.<\/h4>\n

    TCHAR ** UnPackVariantWithStringArray(short nCnt, VARIANT var )
    {
        TCHAR **pBuffer = (TCHAR **) calloc ( nCnt, sizeof (INT)) ;  <\/strong><\/font><\/p>\n

        USES_CONVERSION ;
        SAFEARRAY* pSafeArray  = var.parray ;
        \/\/pointer to array data, actually increments the lock count
        BSTR* bstrArray = NULL ;
        SafeArrayAccessData ( pSafeArray, (void**)&bstrArray);
        for ( int i = 0 ; i < nCnt ; i++ )
        {
            LPTSTR szTmp = OLE2T ( bstrArray [i] ) ;
            int nLen = _tcslen ( szTmp );
            pBuffer [i]= (TCHAR *) calloc ( nLen, sizeof ( TCHAR));
            _tcscpy ( pBuffer [i], szTmp);
        }
       
        \/\/Done wth populating, Decrement the array’s lock count
        SafeArrayUnaccessData(pSafeArray);
        return pBuffer ;
    }<\/strong><\/font><\/p>\n

    these conversion is useful in middleware scenario<\/strong>. in the next article I will explain how to pack array of structure<\/strong> inside a variant.<\/p>\n","protected":false},"excerpt":{"rendered":"

    This is the second post about variant, in this post I I am going to explain, how an array of strings can be packed inside a VARIANT variable. Packing  a array of string inside a Variant int  PackVariantWithStringArray(short nCnt, VARIANT * pVar ) {     USES_CONVERSION ;     \/\/Initialize the VARIANT (Type is SAFEARRAY of… Continue reading Packing a array inside a VARIANT (VC++ 6.0) (Series 2 of N)<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,11,15],"tags":[],"class_list":["post-23","post","type-post","status-publish","format-standard","hentry","category-codeproject","category-mfc","category-win32","entry"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts\/23","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=23"}],"version-history":[{"count":0,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/posts\/23\/revisions"}],"wp:attachment":[{"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/praveenkatiyar.in\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}