Storing and Retrieving Strings

Hi guys,

I am having a confusing time trying to figure out strings and such. I have searched the forums about this, but it still does not clarify what i want to know.

I'm trying to program something that allows me to store, retrieve and delete information. Like an electronic phone contact book. For example, if i were to type a name followed by the contact number, the information will be stored. So if i press a search button and type in the name the corresponding number will appear. And also if i press delete and type in the name the whole name and number entry will be deleted.

So far what i have done is set up variable strings to ask for name and number. So that when i enter the name, another box will pop up asking for the number. I managed to have another object ask for a name and then it will correspond with the number as an answer. However i can only add in one name and number entry, if i try adding in another one the previous entry disappears.

Any help will be appreciated.

Thanks =D

Unless you must use Alice for this program, I'd suggest another approach. This is going to require quite a bit of string processing and a flexible array/list implementation - neither of which is an area Alice is strong in. In particular, there is no function to extract part of an existing string as a new string - which means your data will be separated into many small pieces that you then must keep track of.

Storing text information is also difficult and requires using the scripting option - which is problematic at best in Alice - but if you use that approach, why not use a scripting language (say Python) directly?

What you want to do also has been done in many "office" programs - Excel, Access, etc. - with excellent results and there are a lot of freeware programs out there also.

If - say for the 3D library or just interest in learning Alice/Java - you do want to stay with Alice, you are going to have to set up some sort of list/array structure to hold the data and then update the data via a separate user interface.

One thing to remember here is that any variable specifically associated with a method will be reset to the default once the method is run. If you want to keep it - you will either have to pass it back to the calling program (i.e., make the method a function) or write the value to a world level variable. The latter, in particular, is not good general programming practice but is the only option in Alice.

Yeah i have to use Alice to do it. Its just apart of a small project im doing. Been trying to figure it out the whole day today but i keep getting into dead ends and errors.

I have read dickbaldwins tutorials and he mentions doing a telephone book with strings, i thought it be much easier >.<.

I think i will have to use lists/arrays, my knowledge of Alice isn't very good but i'm still learning !

Though if i were to use a list in alice for this project, how would i go about doing that? Do i make the variable list a string and would i be keeping say 4 items on the list as "default string"?

I held off posting on this because I was hoping someone else would have some good ideas. Quite frankly, everytime I've started something like this in Alice, I've very quickly switched to another approach - the inability to extract a part of a string makes things quite difficult.

As you suspect, you will have to use a list or an array for the names in the book. You add a name to the list each time you want to update the list and then search for a match with the name you want to look up. I find lists are a little more reliable and since, in Alice, you can only have one dimensional arrays, they don't offer a lot of advantages.

The real problem is that you cannot make the entry in the list contain both the name and the phone number - since to get a match, you'd have to type the name and number in to do the search. If you already do know the number, why bother?

You will have to make another list/array with the phone numbers ordered in the same sequence as the names. Then, when you've found the name, look at the "number list" item with the same index for the phone number and have something in the world say it as a string (if you didn't already store it that way).

The real difficulty is keeping the indicies of the two lists synchronized as new names are added or existing ones are deleted. Not really easy - and one error will ruin the whole "phone book" if you use lists.

Good luck.

Thanks DrJim, yeah i was having trouble syncing the two lists together, i think there is something wrong in my coding. I can make it work with just one name and number but it seems to get mixed up when another is added or another after that.

This particular problem has always irritated me, since it shouldn't be very hard - but with Alice, it is. I have a pretty good start - see attached.

The quirks - other than string manipulation - that give problems are that a function can apparently only return a number and that the display of a number as a string is always floating point. Solved most of those - and maybe if you display a number as 321.9999 it won't be too irritating.

Note that you have to be very careful with variable types. Also, though I don't like arrays in Alice very much, that does seem to be the better choice here to keep the name and number arrays synchronized. With lists, I still haven't figured that out.

Looking forward to any feedback as to if you find this helpful.