Speed up 'for next' code?

[BackupUser]

Restored from previous forum. Originally posted by cor.

Can the following code be faster if using other methods?

Code: Select all

 
For s1=0 To 4
 For s2=0 To 4
   For s3=0 To 4
    For s4=0 To 4
     For s5=0 To 4
      For s6=0 To 4;

; do something
;  
     Next s6
    Next s5
   Next s4
  Next s3
 Next s2    
Next s1

Using Windows 98 SE
Registered PB version : 3.2 (Windows)
--------------------------
C. de Visser
Author of Super Guitar Chord Finder
http://www.ready4music.com

[BackupUser]

Restored from previous forum. Originally posted by cor.

Can someone confirm if you leave out the 'i' of the next command the for next loop is faster?

for i= 1 to 1000

next i
;
;
for i= 1 to 1000
;faster
next



Using Windows 98 SE
Registered PB version : 3.2 (Windows)
--------------------------
C. de Visser
Author of Super Guitar Chord Finder
http://www.ready4music.com

[BackupUser]

Restored from previous forum. Originally posted by PB.

> Can someone confirm if you leave out the 'i' of the next command the for next
> loop is faster?

Based on the following test, I'd say no -- it makes no difference. Try the test
as it stands, then remove the "loop" variable name after "Next" and the average
is still roughly the same.

Code: Select all

Debug "Doing 10 tests..."
For test=1 To 10
  begin=GetTickCount_()
  For loop=1 To 20000000 : Next loop
  r=GetTickCount_()-begin : av=av+r
  Debug "Result = "+Str(r)
Next
Debug "Average = "+Str(av/10)

PB - Registered PureBasic Coder

Edited by - PB on 21 July 2002 23:32:18

[BackupUser]

Restored from previous forum. Originally posted by cor.

Try this in lets say 10 nested loops and see the difference?

> Can someone confirm if you leave out the 'i' of the next command the for next
> loop is faster?

Based on the following test, I'd say no -- it makes no difference. Try the test
as it stands, then remove the "loop" variable name after "Next" and the average
is still roughly the same.

Code: Select all

Debug "Doing 10 tests..."
For test=1 To 10
  begin=GetTickCount_()
  For loop=1 To 20000000 : Next loop
  r=GetTickCount_()-begin : av=av+r
  Debug "Result = "+Str(r)
Next
Debug "Average = "+Str(av/10)

PB - Registered PureBasic Coder

Edited by - PB on 21 July 2002 23:32:18

Using Windows 98 SE
Registered PB version : 3.2 (Windows)
--------------------------
C. de Visser
Author of Super Guitar Chord Finder
http://www.ready4music.com

[BackupUser]

Restored from previous forum. Originally posted by fred.

Depending of the inner code, it could be optimized a lot I guess, a least by doing raw inlining (code will be bigger but faster...):

For example:

For k=0 to 4
a(k) = k
Next

Can be replaced logically by:

a(0) = 0
a(1) = 1
a(2) = 2
a(3) = 3
a(4) = 4

which will be of course faster

Fred - AlphaSND