Re: [Pharo-users] what must be instead of the ??

[Roelof Wobben]

Thanks all. This code seems to do the job santaFloorOnBasement     "calculates which step take Santa to the basement"      | index|      index := 1.       [floor ~= -1 ] whileTrue:          [ floor := ((input at: index) = '(' )                 ifTrue: [ floor + 1 ]                 ifFalse: [ floor - 1 ].          index := index + 1 ].               ^ index -1 Roelof Op 9-11-2018 om 09:51 schreef Ben Coman: On Fri, 9 Nov 2018 at 15:25, Roelof Wobben <r.wob...@home.nl> wrote: Hello, I try to solve a adventofcode challenge where I must find out when santa is first at the basement. the floor is there -1. So I thought I use a while loop like this : santaFloorOnBasement      "calculates which step take Santa to the basement"       | index|       index := 1.       ??? when: (floor >=0 ) do:          [ floor := (input at: index = '(' )                  ifTrue: [ floor + 1 ]                  ifFalse: [ floor - 1 ].           index := index + 1 ]. but I cannot find out what must be instead of the ?? I've never used #when:do: so I can't comment on that. I'd be using #whileTrue: which looks like this...  [ condition block ] whileTrue: [ action block ]      <<<     ??? when: (floor >=0 ) do: >>>    [floor>=0] whileTrue:  For further examples review the "senders" of #whileTrue: i.e. highlight then press <CTRL-N> on MS Windows    index is the index of the string which has to start with a 1. floor  and input are both instance variables. floor contains the current floor and input the input of the challenge. Can someone help me figure this out so the next time I can do this on my own. btw you have a problem here...      floor := (input at: index = '(' )  Its not doing what you think and you'll get "Error: only integers should be used as indices" Consider you that two messages are being sent:    * the keyword message...  #at:    * the binary message....  #= Homework :)... what is the third type of message and the evaluation priority of all three. Homework 2...  Review the "implementors" of message #= <CTRL-M> on MS Windows cheers -ben P.S. As it current stands,  you'll get a "SubscriptOutOfBounds" error if the input ends before Santa gets to the basement.  An exercise, fix that using the existing loop. Then consider using an iterator...     input do: [ :bracket |           (bracket = $( ) ifTrue:  [ floor := floor + 1 ]  .          (bracket = $( ) ifTrue:  [ floor := floor + 1 ]    ]. and maybe something else for you to experiment with...     movement := Dictionary new.     movement  at: $( put: 1.     movement  at: $) put: -1.     input do: [ :char |  floor := floor + (movement at: char ifAbsent: [0]) ].  cheers -ben