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+---- Thread: Skipping within a For Loop (/showthread.php?tid=1001)
Skipping within a For Loop - Dimster - 10-23-2022
Logically the answer to my question here is NO but embarrassment from asking stupid coding questions is my Forte.
When you have a loop control range, can you skip a specific step within the range? So for example the For Loop is
For x = 50 to -50
if x = 0 then next
Next
or if there may be a couple within the controlled range is there a way to
For x = 50 to -50
if x = 10 or x = 0 or x = -10 then Next
Next
Thanks
RE: Skipping within a For Loop - Pete - 10-23-2022
There are not stupid questions, only stupid questioners.
Anyway, kidding aside...
Code: (Select All)
FOR i = 10 TO -10 STEP -1
IF i <> 0 THEN
PRINT i
END IF
NEXTThat's how I would code for your first example. There may be others who would do so, differently.
For the second example...
Code: (Select All)
REM Use your mouse wheel to scroll the console output.
$CONSOLE:ONLY
FOR i = 50 TO -50 STEP -1
IF ABS(i) = 10 OR i = 0 THEN
ELSE
PRINT i
END IF
NEXTJust thought I'd have some fun and hand you an empty THEN statement. I use this technique sometimes when I rather write the condition one way more than the opposite way. IF ABS(i) <> 10 and ABS(i) <> 0 in this case. The ELSE part wouldn't be needed if I wrote it that way.
The STEP part is a neat way to control the loop. NEGATIVE 1 allowed use to get the - to + output in these examples. You can also skip using STEP -2, STEP 5, STEP -10, etc. STEP can be used with positive numbers to. FOR i = 0 TO 10 STEP 2 would give us... 0, 2, 4, 6, 8, 10. If we used that exclude zero again, we'd get 2, 4, 6, 8, 10 in the output.
Pete
RE: Skipping within a For Loop - SMcNeill - 10-23-2022
_CONTINUE is what you're looking for.
_CONTINUE - QB64 Phoenix Edition Wiki
RE: Skipping within a For Loop - SMcNeill - 10-23-2022
For x = 50 to -50
if x = 0 then _continue
Next
For x = 50 to -50
if x = 10 or x = 0 or x = -10 then _continue
Next
RE: Skipping within a For Loop - a740g - 10-23-2022
You could use the _CONTINUE keyword to skip the remainder of the loop.
Code: (Select All)
For x = 50 To -50 Step -1
If x = 10 Or x = 0 Or x = -10 Then _Continue
Print x;
NextEdit: Steve, you beat me to it. XD
RE: Skipping within a For Loop - SMcNeill - 10-23-2022
(10-23-2022, 03:54 PM)a740g Wrote: You could use the _CONTINUE keyword to skip the remainder of the loop.
Code: (Select All)For x = 50 To -50 Step -1
If x = 10 Or x = 0 Or x = -10 Then _Continue
Print x;
Next
Edit: Steve, you beat me to it. XD
Dang! If someone had just told me about that nice looking command!
RE: Skipping within a For Loop - Pete - 10-23-2022
That's a new keyword for me, too.
I still like using conditional statements better, and I never resorted to GOTO or THEN as GOTO methods...
Code: (Select All)
FOR i = 1 TO 10
IF i = 5 THEN 100
100
NEXT
' OR...
FOR i = 1 to 10
if i = 5 THEN GOTO bypass
bypass:
NEXTOne new keyword I hope QB64 doesn't develop is POP. POP was available in languages like Atari BASIC, and maybe T.I., as a way to exit a GOSUB without a RETURN. It simply cleared the stack. I think POP screwed a lot of beginner programmers for using other languages and winding up with stack space errors.
Pete
RE: Skipping within a For Loop - Dimster - 10-23-2022
That _Continue is really great. Checked the wiki and Select Case seemed to be missing so I tried it
For x = 1 To 10
Select Case x
Case 1
Print x;
Case 2
_Continue
Case 3
Print x;
Case 4
Print x;
Case 5
_Continue
Case 6
Print x;
Case 7
Print x;
Case 8
_Continue
Case 9
Print x;
Case 10
Print x;
End Select
Next
And it works in Select Case as well. And now that it has been brought to my attention, I think I may have either asked this question before or was reading something similar at the old site. I think I do have an old routine where I used _Continue in a Select Case algorythm. Anyway appreciate your help once again.
RE: Skipping within a For Loop - Pete - 10-23-2022
Well, this is a CASE where _CONTINUE isn't even needed. Also, if you want to make the cases simplified, try...
Code: (Select All)
PRINT
PRINT
FOR x = 1 TO 10
SELECT CASE x
CASE 1, 3, 4, 6, 7, 9, 10
PRINT x;
END SELECT
NEXTNow all examples will do the same thing, but if you start to get into 100's or 1000's of lines of code, keep in mind smaller routines make for easier understanding and debugging.
Pete
RE: Skipping within a For Loop - OldMoses - 10-23-2022
It's not SELECT CASE that's being skipped, but rather the FOR...NEXT.
_CONTINUE will work anywhere in a loop as far as I know, but just be careful where you place it. Since it short circuits the loop it is in, it will skip all subsequent code that occurs after it until the NEXT/LOOP/WEND. You just have to make sure you're not doing something important in the loop after the _CONTINUE.
Code: (Select All)
PRINT
PRINT
FOR x = 1 TO 10
SELECT CASE x
CASE 2
_CONTINUE
CASE 8
_CONTINUE
END SELECT
PRINT x;
NEXT