DevQueryDeviceNames - Example Code

This example uses DevQueryDeviceNames to return the names, descriptions, and data types of supported devices for a presentation driver. The first call to DevQueryDeviceNames determines the number of names, description, and data types available; after allocating the arrays, the second call actually returns the information in the arrays.

#define INCL_DEV                /* Device Function definitions  */
#define INCL_DOSMEMMGR          /* DOS Memory Manager Functions */
#include <os2.h>

BOOL  fSuccess;         /* success indicator                    */
HAB   hab;              /* Anchor-block handle                  */
LONG  pldn = 0L;        /* number of device names/descriptions  */
LONG  pldt = 0L;        /* number of data types                 */
PSTR32 aDeviceName;     /* array of device names                */
PSTR64 aDeviceDesc;     /* array of device descriptions         */
PSTR16 aDataType;       /* array of data types                  */

/* query number of supported names/descriptions/data types
   (pldn & pldt both 0) */
fSuccess = DevQueryDeviceNames(hab, "IBM4201.DRV", &pldn,
                               aDeviceName, aDeviceDesc, &pldt,
                               aDataType);

if (fSuccess)
   {
   /* allocate arrays */
   DosAllocMem((VOID *)aDeviceName, (ULONG)pldn*sizeof(STR32),
               PAG_COMMIT | PAG_WRITE);
   DosAllocMem((VOID *)aDeviceDesc, (ULONG)pldn*sizeof(STR64),
               PAG_COMMIT | PAG_WRITE);
   DosAllocMem((VOID *)aDataType, (ULONG)pldt*sizeof(STR16),
               PAG_COMMIT | PAG_WRITE);

   /* query supported device information */
   fSuccess = DevQueryDeviceNames(hab, "IBM4201.DRV", &pldn,
                                  aDeviceName, aDeviceDesc, &pldt,
                                  aDataType);
   }