Silly question...

[mark smit]

Hello,


Why does the following code seem to slow down exponentialy? If I
substitute the variable "mytype" with a long, the program seems to
run at a steady speed...

Does this have anything to do with the "preserve" feature of redim?

#compile exe
#include "win32api.inc"


type mytype
    n as string * 4096
end type


function pbmain as long
    dim result as long
    dim hdlg as long
    dim lut() as mytype
    dim i as long
    
    
    dialog new 0,"test",1,1,256,64,%WS_POPUP or %WS_CAPTION or %WS_SYSMENU to hdlg
    control add label,hdlg,100,"",4,4,200,12
    control add label,hdlg,200,"",4,18,200,12
    dialog show modeless hdlg
    
    
    dialog doevents to result
    
    
    
    for i = 0 to 100000
        redim preserve lut(i)
        
        
        if int(i mod 10) = 0 then
            dialog doevents to result
            if (result = 0) then exit for
        
            control set text hdlg,100,format$(i,"array reallocated(#)")
        end if
    next i
    
    
    
    do until result = 0
        dialog doevents to result
    loop
end function

------------------
Cheers

[Gregery D Engle]

Mark,

The reason your code is slow is 1)

within your for .. loop you are reallocating the array and saving
the information. What I normally do is this case, is resize the
array before the for..loop or after or both. never within. Very
slow performance.

#COMPILE EXE
#INCLUDE "win32api.inc"

[b]%Max = 100000[/b]

TYPE mytype
    n AS STRING * 4096
END TYPE

FUNCTION PBMAIN AS LONG
    DIM result AS LONG
    DIM hdlg AS LONG
    DIM lut() AS mytype
    DIM i AS LONG


    DIALOG NEW 0,"test",1,1,256,64,%WS_POPUP OR %WS_CAPTION OR %WS_SYSMENU TO hdlg
    CONTROL ADD LABEL,hdlg,100,"",4,4,200,12
    CONTROL ADD LABEL,hdlg,200,"",4,18,200,12
    DIALOG SHOW MODELESS hdlg

    DIALOG DOEVENTS TO result
    [b]REDIM lut(0 TO %Max)[/b]

      FOR i = 0 TO 100000
        IF INT(i MOD 10) = 0 THEN
            DIALOG DOEVENTS TO result
            IF (result = 0) THEN EXIT FOR

            CONTROL SET TEXT hdlg,100,FORMAT$(i,"array reallocated(#)")
        END IF
    NEXT i

    DO UNTIL result = 0
        DIALOG DOEVENTS TO result
    LOOP
END FUNCTION

- The reason a long runs faster then a string is 1) a long is only
32 bits, and your string is 32768 bits long. Also there
has been discussions about that longs are native to the operating
system within a 32 bit programming environment. Lance would be
the guy to ask about that.

- For this test I didn't do it but for a real test I would popuplate
the UDT via pointer to increase speed. Although, you will
still have to redim or dim the UDT without pointer.

Hope that helps,

------------------
-Greg