Constructing Descriptor Arrays

Procedure

Follow the steps listed below to construct descriptor arrays:

1. Construct a set of descriptors.

   The following code fragments illustrate how to construct a CDesCArrayFlat and a CPtrCArray . Both array types can accept any type of descriptor as source when adding a new array element.

            
             
            
            _LIT( KText1,"abcdefg" );
   _LIT( KText2,"hijk" );
   _LIT( KText3,"lmnopqr" );
   _LIT( KText4,"stuvwxyz" );
   ...
   TBufC<8> buffer1( KText1 );  // a non-modifiable buffer descriptor
   TBuf<8>  buffer2( Ktext2 );  // a modifiable buffer descriptor
   ...
   TPtrC  ptr1( Ktext3 );       // a non-modifiable pointer descriptor
   TPtr   ptr2;                 // a modifiable pointer descriptor 
   ptr2 = buffer1.Des();        // pointing to the data in buffer1
   ...
   HBufC* heapbuff = HBufC::NewL( 8 );  // a heap descriptor
   *heapbuff = KText4;
           

   Note: Constructing and using a CDesCArraySeg is same as using CDesCArrayFlat .

2. Add the five descriptors to CDesCArrayFlat as shown in the following code.

            
             
            
            CDesCArrayFlat* descarray;
   ...
   descarray = new( ELeave ) CDesCArrayFlat( 5 );
   ...
   descarray->AppendL( buffer1 );
   descarray->AppendL( buffer2 );
   descarray->AppendL( ptr1 );
   descarray->AppendL( ptr2 );
   descarray->AppendL( *heapbuff );
   ...
   TInt len = descarray->MdcaPoint( 2 ).Length();  // information about
                                                   // the third element
   ...
           

3. Add the five descriptors to CPtrCArray as shown in the following code.

            
             
            
            CPtrCArray* ptrcarray;
   ...
   ptrcarray = new( ELeave ) CPtrCArray( 5 );
   ...
   ptrcarray->AppendL( buffer1 );
   ptrcarray->AppendL( buffer2 );
   ptrcarray->AppendL( ptr1 );
   ptrcarray->AppendL( ptr2 );
   ptrcarray->AppendL( *heapbuff );
   ...
   TInt len = ptrcarray->MdcaPoint( 2 ).Length();  // information about
                                                   // the third element
   ...