slow register variables

[Stuart McLachlan]

I'm very much shooting from the hip here, but what if you use

k = 7&

I think we have a record. A possible solution posted more that 11 years after a question

[Brice Manuel]

I think we have a record. A possible solution posted more that 11 years after a question

11 years might be a necroposting record.

[Bud Durland]

It's because the font with the posting date is very small, and although I have a pair of glasses, my curiosity hasn't overcome my vanity.

[Theo Gottwald]

Lets see, after 11 Years I believe this topic ist still of interest.

Let's try this one is without REGISTER Variables ...

FUNCTION PBMAIN () AS LONG

LOCAL tc AS LONG
#REGISTER NONE
'=====================================================================

        tc = GetTickCount()

       LOCAL k AS LONG, i AS LONG
       LOCAL  j AS LONG

        FOR i = 1 TO 30000
        FOR j = 1 TO 30000
        k+=7
        NEXT j
        NEXT i

     ? STR$(GetTickCount - tc)

END FUNCTION

'=====================================================================

RESULT: 2000 Ticks

Now we use REGISTER Variables.
Should it be faster?

FUNCTION PBMAIN () AS LONG

LOCAL tc AS LONG

'=====================================================================

        tc = GetTickCount()

       REGISTER i AS LONG, j AS LONG
       LOCAL  k AS LONG 

        FOR i = 1 TO 30000
        FOR j = 1 TO 30000
        k+=7
        NEXT j
        NEXT i

     ? STR$(GetTickCount - tc)

END FUNCTION

'=====================================================================        
END FUNCTION

RESULT: 2047 Ticks

It's even slower!

Maybe because of some Details of the FOR-LOOP.

If you do not want to pay the "47 Ticks", just use a DO ... LOOP and IF.

Now lets unleash the REAL POWER of PB REGISTER Variables!

By placing "k" into the REGISTER and removing "i".

     FUNCTION PBMAIN () AS LONG

LOCAL tc AS LONG

'=====================================================================

        tc = GetTickCount()

       REGISTER k AS LONG, j AS LONG
       LOCAL  i AS LONG  

        FOR i = 1 TO 30000
        FOR j = 1 TO 30000
        k+=7
        NEXT j
        NEXT i

     ? STR$(GetTickCount - tc)

END FUNCTION

'=====================================================================

RESULT: 516 Ticks USING PB REGISTER Variables!
Thats 4 times as fast as without using the REGISTER Variables!

Using the Loop-Variables as a REGISTER Variable is only good, if the Loop Variable is also often used inside the Loop.

Best is, if you put the most often accessed Variable into the REGISTER.