[Windows 4.3 B4] Really strange bug with arrays

[RocketRider]

Really strange bug with arrays

Code: Select all

Global Count

Procedure.l Number(Max.l)
lResult.l = Count
Count + 1
ProcedureReturn lResult % Max
EndProcedure


Dim counts(10)

For i=0 To 1000
counts(Number(10)) + 1
;The following works
;x = Number(10)
;counts(x) + 1
Next

For n=0 To 9
Debug counts(n)
Next

[Deeem2031]

This is the same bug: http://www.purebasic.fr/english/viewtop ... highlight=

[Kaeru Gaman]

KMA!

... really strange, and I never before heard of it ...

I wonder why I never happened to fall into that pit...

[ABBKlaus]

no bug, the procedure Number() is called twice.

ASM Code :

Code: Select all

  PUSH   dword 10
  CALL  _Procedure0 ; <- first call to Number()
  MOV    ebx,eax
  MOV    ebp,dword [a_counts]
  SAL    ebx,2
  MOV    ebx,dword [ebp+ebx]
  INC    ebx
  PUSH   ebx
  PUSH   dword 10
  CALL  _Procedure0 ; <- second call to Number()
  MOV    ebx,eax
  MOV    ebp,dword [a_counts]
  SAL    ebx,2
  POP    dword [ebp+ebx]

The short writing of the code

Code: Select all

counts(Number(10)) + 1

is expanded to this

Code: Select all

counts(Number(10))=counts(Number(10)) + 1

[Deeem2031]

Yea, thats the same we found out in the old thread, but its still a bug because it's not intentional if you write the short version.

[Joakim Christiansen]

but its still a bug because it's not intentional if you write the short version.

Yeah, because how would anyone (normal users) know about this behavior? This is clearly not what a user wants.