Q40190: Same Access Speed for Static, Dynamic Arrays If Debug Is On

Article: Q40190
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom | mspl13_basic
Last Modified: 14-DEC-1989

The code shown below demonstrates that the access time for an array is
not dependent upon whether the /AH option is used. Furthermore, a
static array requires the same amount of access time as a dynamic
array when executed from within QB.EXE or when compiled with the debug
(BC /d) option. Static-array access is faster than dynamic-array
access when compiled without the debug (BC /d) compiler switch.

This information applies to QuickBASIC Versions 4.00, 4.00b, and 4.50,
Microsoft BASIC Compiler Versions 6.00 and 6.00b for MS-DOS and MS
OS/2, and Microsoft BASIC PDS Version 7.00 for MS-DOS and OS/2.

The following times were required for the sample program below when
executed under QuickBASIC Version 4.50 using the indicated options on
an AT compatible running at 10 megahertz with a 6-megahertz 80287
chip:

   Array Type       QB.EXE      BC.EXE /d      BC.EXE No Debug
   ----------       ------      ---------      ---------------
                    With an 80287 coprocessor:

   Huge             23.22       38.05           30.02
   Static           23.17       38.10           17.96
   Dynamic          23.24       38.07           30.32

                    Without an 80287 coprocessor:

   Huge             88.65       105.39          97.5
   Static           88.64       105.40          82.6
   Dynamic          88.64       105.45          97.49

Earlier versions do not allow huge (larger than 64K) arrays.

The following is sample code:

' $DYNAMIC
DIM ar0(20000)

' $STATIC
DIM ar1(2000)
' $DYNAMIC
DIM ar2(2000)

s# = TIMER
FOR j = 1 TO 100000
   ar0(1) = ar0(1) + ar0(0)
NEXT
PRINT TIMER - s#; " seconds elapsed  FOR HUGE"

s# = TIMER
FOR j = 1 TO 100000
   ar1(1) = ar1(1) + ar1(0)
NEXT
PRINT TIMER - s#; " seconds elapsed FOR STATIC"

s# = TIMER
FOR j = 1 TO 100000
   ar2(1) = ar2(1) + ar2(0)
NEXT
PRINT TIMER - s#; " seconds elapsed FOR DYNAMIC"

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