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Topic: Menu on LCD: strings, multi-dimensional arrays? (Read 1 time) previous topic - next topic


Sep 01, 2010, 05:43 am Last Edit: Sep 01, 2010, 05:44 am by willis Reason: 1
Hey guys.  I've searched around a bit before posting, but I wasn't sure what to look for, so forgive me if this has been answered.

What I'm looking to accomplish is the following:

Have a series of user-navigable menus drawn using the liquidCrystal library.

I've come up with some pseudo-code for what I want to do, but it's long enough that I'll just try and summarize what I have in mind.

I'd like to have:

  • an int corresponding to which "menu" the user is in.
  • an int corresponding to the selected "item" in that menu
  • a bool corresponding to whether they are "editing" that item's "value"
  • an array of names of "menu"s to be written to the screen for the user (id corresponds to the menu int.)
  • an array of names of "items" in each menu (again the id's would match my "selected item" int)
  • an array of values for each "item" in each "menu"  

I'd ideally build in such a way that when I'm drawing the menu I can just use these variables plugged into the same function no matter what the menu structure looks like.  This way, if I need to add items to the menu later it's no big deal -- I just adjust the lengths of the arrays and that's it.

So here are the questions I have:

  • what's the best way to structure this?  I'm thinking of a 2- or 3-dimensional array, but this starts to get complex when I try and think about how to link the values of items to their names.  Another thought was to create a new class that handles all of this data stuff, but I don't know C well enough to know if that's a good approach.
  • what's the best way to handle the large number of strings I'll be needing to keep track of?  If it makes it any easier, I know they'll all be less than a certain length, and can pad them out to be all the same length with whitespace.
  • The values of the menu items will be in a variety of formats, including some which are a list of text-based options that correspond to numeric values.  (one example being the string "1/8000" which would represent the int 125)
  • Is there a better way to be doing this?  I don't have any *real* formal training in CS, so I'm sure there are better ways to do this.


(In my opinion) I think that "Linked Lists" are a good way of doing menus.

There is a section for this in the book "C: The Complete Reference" (great book)

I found something for you to look at http://cslibrary.stanford.edu/103/LinkedListBasics.pdf.  Basically, you use a "next"/"previous" approach, and I have found it to be a successful way to use XML data.  The trick is that you add another pointer called "parent"; you go through the list and print every element with that parent.

There is also a library out there somewhere if you keep digging around.

If you have lots of strings, it is best to look into PROGMEM


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