survival guide / primer

[Edwin Knoppert]

I see it's for beginners.
I wouldn't start about pointers but i would like to see the BYREF example.

Also applies to the PureBasic helpfile imo, it's hard to remember how byref worked again.

This issue was discussed here once:
viewtopic.php?t=9027

However the solution to pass the pointer makes it actually harder, compare this:

Code: Select all

; same for long 
Procedure SetLong(*p.LONG) 
  *p\l = 15 
EndProcedure 

SetLong(@i) 
Debug i 

With:

Code: Select all

Sub SetLong( p As Long )
    p = 15
End Sub

Dim p As Long
SetLong p

[blueznl]

made some minor additons to the toc (symbols like ! @ # $ % etc.)

i'll have a look at the byref / byval thing, edwin, but what's exactly the problem?

[Edwin Knoppert]

1) The byref thing is hard to find out yourself, so a tutorial worth imo.

2) The example once given by a user looks a bit complicated (much pointer stuff)
Maybe this one can be simplified anyway?

[blueznl]

mmmm... pure has no byref parameter, everything into a procedure always goes byval, so the only way to do it is byval thus via a pointer...

i know that's not what you would like to hear

Code: Select all

procedure xyz(*a.LONG)
   *a\l = 2
endprocedure

q.l = 1
xyz(@q.l)

i think it's the only way to do it, to be honest: instead of passing the variable value you pass the location of the variable in memory

i make a note of it, and see where the proper place in the primer is to add this

(anybody correct me if i am wrong: there is no byref parameter is there?)

[Edwin Knoppert]

It's not a big issue to do it like above.
But byref seems to be a forgotten option to pb users.
I don't see much asking (or they must be really clever and found out themselves already )

If you add it and make a BYREF remark, we can all find it again later on.

[blueznl]

i think, in general, using vars by ref is not the best thing to do (in general) but i admit that's entirely a personal opinion i prefer by ref icw. structs instead of passing each variable by ref, or use globals

it's a VERY personal decision

i'm adding some byref stuff now

[Searhin]

@blueznl

Just read your latest chapter.

Note: in your part on enumeration (ch 4. you write the first element would get the number 1, but actually it is 0.

Keep up your great work!

[blueznl]

few changes:

- fixed enumeration starting at 0
- added byref/ byval
- bit larger index
- few small changes here and there

[blueznl]

- bunch of small fixes
- expanded explanation of numbers / id's / handles / #pb_any

[blueznl]

updated

[blueznl]

added stuff on strings and command lines

http://www.xs4all.nl/~bluez/datatalk/pure20.htm

[blueznl]

little more on sprites

[Shannara]

This is still awesome There is something concerning structures that are not listed in the PB manual that is a limitation to structures. You cannot use a structured member in another structure's member array to grab a value.

Ex:

Code: Select all

Structure strA
  memArray.l[10] ;0 - 9
EndStructure

Structure strREF
  memLocation.l
EndStructure

myREF.strREF
myStruct.strA

X.l
For X = 0 to 9
  myStruct\memArray[X] = (X + 1)
Next

myREF\memLocation = 5
#MEMLOC = 5
X = 5

Debug str(myStruct.memArray[#MEMLOC])  ; This show 6
Debug str(myStruct.memArray[5])  ; This show 6
Debug str(myStruct.memArray[X])  ; This show 6
Debug str(myStruct.memArray[myRef\memLocation])  ; This show 0!!!!

As you can see, you cannot use a structured member to grab a value from another structure's array member ... Really weird. This is with the newest PB w/ all updates.

[freak]

You code is not correct PB syntax and does not compile.
After correcting it, i get the proper output.

[Shannara]

Sorry about that, I corrected it locally as well. damn, it must only have that issue with sprites grr, I'll have to post a more full filling example.