Why is Debug 30/4 equal to 7 instead of 7.5 ?

[Joris]

Why is Debug 30/4 equal to 7 instead of 7.5 ?

Code: Select all

a.f=30
b.a=4
Debug 30/4
Debug a/b

It makes using a float always necassary even when I just wonna be able to detect if a division is integer or not ?
(Does that make sence ? I'm getting confused now.)

[Marc56us]

Why is Debug 30/4 equal to 7 instead of 7.5 ?

Code: Select all

a.f=30
b.a=4
Debug 30/4
Debug a/b

It makes using a float always necassary even when I just wonna be able to detect if a division is integer or not ?
(Does that make sence ? I'm getting confused now.)

Force it (add .0)

Code: Select all

a.f=30
b.a=4
Debug 30/4     ; (show 7)
Debug 30/4.0   ; (show 7.5)
Debug a/b      ; (equal 7.5)

Code: Select all

If Int(30 / 4.0) = 30 / 4.0
    Debug "Integer"
Else
    Debug "Not integer"
EndIf

[PMV]

In calculations, PB will use the variable type that matches the used variables.
That means if you have a division of just intenger, the result will be an integer.

If you need to convert on the fly from integer to float, as the calculation based
on only integer variables needs to be done in floatingpoints, you can add
"0.0 +" at the beginning of the calculation.

MFG PMV

Code: Select all

a.a=30
b.a=4
Debug a/b
Debug 0.0 + a/b

Edit:
If you just want to know if there is remainder after the calculation, use Mod()
Because Mod() is a function and expects floatingpoints, the integer variables
will be converted to floatingpoints when passed to Mod() and so no problems.

Code: Select all

a.a = 30
b.a = 4
If Mod(a, b)
  Debug "not integer"
EndIf

[TI-994A]

Why is Debug 30/4 equal to 7 instead of 7.5?

To avoid this, simply cast the output:

Code: Select all

Debug StrF(28/4)   ; = 7
Debug StrF(30/4)   ; = 7.5

...I just wonna be able to detect if a division is integer or not?

An alternative approach:

Code: Select all

If Mod(28, 4)
  Debug "Not Integer"
Else
  Debug "Integer"
EndIf
; = Integer

If Mod(30, 4)
  Debug "Not Integer"
Else
  Debug "Integer"
EndIf
; = Not Integer

[Joris]

In calculations, PB will use the variable type that matches the used variables.
That means if you have a division of just intenger, the result will be an integer.

A strange conclusion, to me.

Still confusing the need of using those tricks to get a correct value debugged, but yeah...

Thanks.

[infratec]

In 'C' you have the same behaviour.

[DontTalkToMe]

Still confusing the need of using those tricks to get a correct value debugged, but yeah...

It's not really a trick, this is how languages usually works.

30 and 4 are integers.

30.0 and 4.0 are floats.

Integer division results in integers, not floats.

Float division results in floats.

If one of the operands is a float, the other one is also converted to float so you get a float division.

Unless there is a bug in the compiler: http://www.purebasic.fr/english/viewtop ... =4&t=59422