'print 10 t's



For t = 1 To 10 'stop t at 10

    Print t

Next



'so t is 10...but...



Print

Print

Print t 'this show 11 now?

For t = 1 To 10.5 Step 1

Next

Print t ' What should t be?

(08-24-2023, 01:02 PM)mnrvovrfc Wrote: BASIC always behaved this way about FOR... NEXT. Since Dartmouth. Many programs depend on this "quirk".

This could cause problems with an _UNSIGNED variable used like this:

Code: (Select All)

DIM u AS _UNSIGNED INTEGER
FOR u = 10 TO 0 STEP -1
PRINT u
NEXT

Expect "u" to be -1? Read the code again. Or if it were possible in QuickBASIC to compile in debug mode it would return a runtime error. This is something that never occurred to me while using QuickBASIC or QBasic. (scratch head)

Quote:

• DO UNTIL or DO WHILE used with LOOP: The condition is evaluated before running the loop code.
  UNTIL checks if the condition is false each time before running code.
  WHILE checks if the condition is true each time before running code.
  
• DO used with LOOP UNTIL or LOOP WHILE: The code block will run at least once:
  UNTIL checks if the condition is false before running loop code again.
  WHILE checks if the condition is true before running loop code again.
  

Quote:

• NEXT ends the FOR loop code block and increments the counter to the next value even when it exceeds the stop limit.
  

Quote:

• statements will execute repeatedly while condition is a non-zero value.
  
• EXIT WHILE can be used for emergency exits from the loop in QB64 only.
  
• A DO...LOOP can use the same DO WHILE condition to get the same results.
  
• WHILE loops only run if the WHILE condition is True.
  

Quote:

• Only one conditional evaluation can be made at the start or the end of a DO...LOOP.
  
• DO UNTIL evaluates a condition before and inside of the loop. The loop may not run at all.
  
• LOOP UNTIL evaluates a condition inside of the loop. It has to loop once.
  
• Skips the loop or loops until an evaluation becomes True.
  

Quote:Avoid changing the FOR counterVariable's value inside of the loop. This obfuscates code and is a poor programming practice.
Once the loop has been started, changing the variables holding the startValue, stopValue or increment value will not affect loop execution.

'For - Next, letzten zugewiesenen Wert verhindern - 24. Aug. 2023



$Console:Only

Option _Explicit



Dim As Integer i, j



For i = 1 To 5

  Print i

Next



Print



'Wert ist jetzt 6, da die letzte Pruefung

'der Abbruchbedingung noch an i uebergeben wird.

Print i * 5



Print: Print

Print "Letzte Zuweisung verhindern"



Print

For j = 1 To 5 Step 1

  Print j

  If j = 5 Then

    'Keine Zuweisung mehr

    Exit For

  End If

Next



Print

Print j * 5



End

'For - Next, letzten zugewiesenen Wert verhindern - 24. Aug. 2023



$Console:Only

Option _Explicit



Dim As Integer i, j, k



For i = 1 To 5

  Print i

Next



Print



'Wert ist jetzt 6, da die letzte Pruefung

'der Abbruchbedingung noch an i uebergeben wird.

Print i * 5



Print: Print

Print "Letzte Zuweisung verhindern"



Print

For j = 1 To 5 Step 1

  Print j

  If j = 5 Then

    'Keine Zuweisung mehr

    Exit For

  End If

Next



Print

Print j * 5



Print: Print

Print "Im Gegensatz zu QuickBasic und QBasic funktioniert ein"

Print "Abbruch mit >Exit While< auch in QB64; aber nur dort."



While k < 10

  k = k + 1

  Print k

  If k = 5 Then

    Exit While

  End If

Wend



Print

Print k

Print

Print k * 5



End

(08-24-2023, 12:51 PM)DSMan195276 Wrote: It's because `FOR` works by first incrementing the loop variable and then checking if it is greater than the end value you gave. For your loop, the first time `t` is greater is when it is incremented to 11.

The reason it works this way is because depending on your `STEP` and what end number you use, you might not hit the last number at all and instead skip right over it. Imagine you did this:

Code: (Select All)

For t = 1 To 10.5 Step 1

Next

Print t ' What should t be?

Obviously `t` cannot be 10.5 at the end because 10.5 will never be hit by the loop. Instead it works identical to your loop,`t` gets incremented to 11 and since that's greater than 10.5 the loop stops there.