Parse tree and grammar information - grammar

Does anyone know where to find good online resources with examples of how to make grammars and parse trees? Preferably introductory materials.
Info that is n00b friendly, haven't found anything good with Google myself.
Edit: I'm thinking about theory, not a specific parser software.

Not online, but maybe you should take a look at Compilers: Principles, Techniques, and Tools (2nd Edition) by Aho et al. This is a standard text that has been evolving for 30 years (if you count the 1st Dragon Book, published in 1977

Well, here's where I learned it...
http://www.cs.uiuc.edu/class/sp08/cs273/
Click on the lectures tag, scroll through till you find the lectures on the material you are talking about.
Love my alma mater. God bless them, they never take down their lectures in any class and you can go and read any of them anytime you want.
edit: Looks like you want lecture11

Antlr?
http://www.antlr.org/
Has a quite good IDE for designing a grammar, and a lot of generators for different languages.

www.goldparser.com
The tools are free and good to work on. It has technical and theoretical tutorials, lots of info, tools and code generators for many langs.

in C,C++ use lex and bison
in java use ANTLR
this is a beautiful antlr video tutorial

Related

Route for learning Smalltalk aka Squeak

Calling Jedi Masters of the Smalltalk universe,
I have knowledge of C++/Python/Perl and have been coding for 5+ years now.
I have to fork Scratch - MIT's Visual programming language to add support for a robotic kit. Scratch is created using Squeak, which is an implementation of Smalltalk.
I am planning to read A Little Smalltalk - By Timothy budd followed by Sqeak By Examples - By Oscar Nierstrasz [http://squeakbyexample.org/]
Do you think this is a good idea ?. What would you suggest ?. Are there free video tutorials I can watch.
End objective is to be able to make sense of scratch codebase. I want to get hang of smalltalk once before I can make sense of the (as of now) weird looking Squeak development environment and its ways.
Luke Smallwalker
Actually, I work with the core developers of Scratch for Arduino! It may be a good start for you to take a look at its code.
I think A Little Smalltalk goes a bit too deep for what you'll need. Squeak by example is, IMO, much better suited as an entry point to the language.
Also, you may want to take a look at Prof Stef for Amber, which is not an intro to Squeak but to Amber Smalltalk. Anyway the syntax is pretty much the same and it will get you a first good idea of what Smalltalk feels like.
HIH, good luck!
[edit] Yesterday I stumbled upon this great article explaining how to read Smalltalk code for Java/C++ developers.
check out my youtube tutorial series Squeak from the very start
http://www.youtube.com/playlist?list=PL6601A198DF14788D&feature=viewall
I have read through "Squeak By Example" and I would say it is very good. I haven't seen "A Little Smalltalk" I think it might be a little outdated because it is from 1987.
after reading "Squeak By Example" I came across BotsInc it might be useful to go BotsInc even though it might seem a bit childish at first. Squeak By Example would be better to understand Smalltalk more fully.
this is a small squeak tutorial that might help too http://scratch.mit.edu/forums/viewtopic.php?id=39196
Stephan B Wessels has a Laser game project that was really useful for me when learning Smalltalk (in Squeak). You can follow and code along here: http://squeak.preeminent.org/tut2007/html/index.html
On to Smalltalk by Patrick Henry Winston is a succinct introductory book that you can get pretty cheaply used at http://www.amazon.com/On-Smalltalk-Patrick-Henry-Winston/dp/0201498278/ref=cm_cr-mr-title

Information about Evolutionary Art

I have begun to do some research about Evolutionary Art algorithm. I read a lot of documents about it. But it seems not easy to understand.
The website http://picbreeder.com is a great example for this. But I don't need this in the beginning because it is too complex.
Where can I find some simple code about this in Java? I think read code could help me much.
Thanks!!!
"Evolutionary Design by Computers" By David Bentley (amazon) has a couple of chapters on evolutionary art. However i dont think it includes any code / pseudocode. The canonical GA should do all you need, however the termination condition could be tricky as art is a subjective subject. (Not objective and therefore enumerable)
Hope this helps...
It looks like the EJC library might help you out, and it looks like a number of open source projects/tools come up if you Google for "java evolutionary computing."
I don't know how simple it is, and believe me it needs to be cleaned up a bit, but I have something that might get you started at https://github.com/murmux/Evo/tree/master/assignment2c It doesn't deal with art, rather game theory, but you can use it under the terms of the GPLv3 if you'd like. That uses Genetic Programming... I have another example using a more vanilla EA I might put up later.
Instead of evolving programs to play "Iterated Prisoner's Dilemma," you would evolve programs to generate an art work. The fun part is coming up with a way to "score" an image for its fitness. (Although Picbreeder seems to skip scoring by having you pick the mating pool directly...)
Check this app: EvoPic, its An evolutionary picture creator that uses Steady-State Genetic Algorithm, to produce evolutionary pictures by drawing uni-code characters in a picture box.
Example:

Tools to generating a grammar using examples?

This answer shows a pretty example of using a parser generator to look through text for some patterns of interest. In that example, it's product prices.
Does anyone know of tools to generate the grammars given training examples (document + info I want from it)? I found a couple papers, but no tools. I looked through ANTLR docs a bit, but it deals with grammars; a "recognizer" takes as input a grammar, not training examples.
This is a machine learning problem. You can at best get an approximation. But I don't think anybody has done this well, let alone released a tool. (I actively track what people do to build grammars for computer languages, and this idea has been proposed many times, but I have yet to see a useful implementation).
The problem is that for any fixed set of examples, there's a huge number of possible grammars. It is easy to construct a naive one: for the fixed set of examples, simply propose a grammar that has one rule to recognize each example. That works, but is hardly helpful. Now the question is, how many ways can you generalize this, and which one is the best? In fact you can't know, because your next new example may be a total surprise in terms of structure. (Theory definition: A language is the set of sentences that comprise it).
We haven't even talked about the simpler problem of learning the lexemes of the language. How would you propose to learn what legal strings for floating point numbers are?
One tool that does this is NLTK. I Highly recommend it, and the O'Reilly book that covers it is available free online. There are tools for parsing, learning grammars, etc... The only downside is that it is mainly a research rather than production tool, so the emphasis isn't on performance.
NLTK is able to construct grammar from labeled training samples, which is exactly what you are asking. Have a look at the great docs and the book. (My last experience with it also had it working on the JVM through Jython without any issues.)

Learning Cocoa. Should I delve into Apple's documentation?

I have built some basic apps for iPhone and Mac with a general understanding of Cocoa, but haven't had a detailed understanding. Now I want to go deeper.
I have just finished the Objective-C documentation at MacDevCenter. It was great to get in-depth look but took far too much time, specially because a lot of it is conceptual, and it's hard to build detailed examples to make use of the concepts.
Now I am on to Cocoa, but feel like it would be too much work to go through 250 page documents for Cocoa itself, then KVC, Cocoa Bindings, and Core Data.
Would I be better off at this stage picking up a good book on Cocoa (Hillegass' is too sparse I think) or should I just bite the bullet and go through the docs?
Apple's documentation is generally excellent. The API reference in the very least is some of the best I've read (right up there with Java's API reference), and is a very valuable asset.
I'd suggest reading the overview pages for topics you're interested in to get a general "feel" for how they work and a starting point, and then just start writing code. You can refer to the documentation to fill in blanks that you encounter while writing code.
Writing a small project to exercise your use of APIs you'd like to learn is a great way to get started.
I've found Hillegass's book to be far from sparse. In fact, I've found it to be one of the most dense books on programming I've read. I've re-read most of the chapters at least 4 times, and each time understood more. By re-reading, I've understood the reason he included a certain paragraph and how it fits with the bigger picture. He spells everything out very clearly and doesn't waste words. I'm amazed at the amount that's contained in that book.
You mentioned that you want to learn by doing, instead of by reading. The Hillegass book has a section at the end of each chapter where you put what you've learned to the test, by building an application.
Of the three things you talked about, KVC, Cocoa Bindings and Core Data, the first two are covered very well. I did find the Core Data chapters to be a lot more sparse. That's the only part of the book that I haven't been able to understand without other documentation. The Pragmatic Programmers book covers it much better.
Anyway, the answer to your question is: it depends. If you've managed to work your way through the Mac Dev Center documentation, it may be that you're the kind of person who learns easily from that style of resource. If you like learning from books, the best one is Hillegass.
I'd recommend an excellent book released some time ago: ‘Cocoa Design Patterns’ by Erik M. Buck and Donald A. Yacktman.
Of course you can dive into Apple's documentation, but to me, I found Hillegass' book is a good start for learning Cocoa. The value of the book, I think, is the introduction of the conventions and idioms of Cocoa.
Is it really clear for a new Cocoa developer to find out information on issues like when and when not to send message autorelease to an object? You can argue that a single Googling will do, but how do you know there are these kind of issues in the first place?
Go get a good book, look through it and take notes. It could save your time. For me, on Cocoa, the book is Hillegass'.
Hillegass' book will drive you to the free documentation every time he fails to make sense in order to be "funny" (i.e. every other paragraph) anyway, so unless you just want to give him $40, you will be much better off sticking to what Apple gives you au gratis. At the very least you won't pick up any of his horrible UI design habits.
You don't really need to go through ALL the bindings and Core Data docs page by page--half of it is stuff you'll likely never use. Knowing where to look for more information is far more valuable a skill than memorizing APIs.
The reference is great and invaluable, but might not be the easiest way to start coding (as people have mentioned).
I started looking at the stanford lectures on iphone development, then coded as I went along. I've actually used them as reference once or twice as well... They are available on itunes for free.
It depends on what other programming experience you have and how you learn best. If you're fairly new to programming in general, I'd recommend Hillegass to start. If you're fairly competent at OOP but don't know Objective-C, you can go for Apple's "Introduction to The Objective-C Programming Language" to learn ObjC's language features. If you've programmed using paradigms other than OOP, you could look for general OOP book recommendations here on SO (e.g. "Best Referece to learn OOP independent of languages?"). I also second Jonatan's recommendation to check out what programming videos iTunes University offers. They are recordings of lectures from top-tier universities and generally of good scholastic quality (I only qualify this with "generally" because I haven't seen them all; the ones I have seen invariably were of quality). No matter where you go to learn ObjC and Cocoa, you'll still yourself using Apple's docs as reference.
As you learn, you might also find CocoaDev a useful ancillary source.
Aaron Hillegass's book is the text for his one-week cocoa development seminar, and it has been revised over several years of teaching Cocoa to beginners. Aaron's course is where Apple sends their own employees, now that they don't do the Cocoa course in-house anymore.
Apple's documentation is an excellent reference, but I agree that it's a huge resource to try to learn Cocoa from in the first place. Besides, you probably don't need to know the whole API up front -- just learn each part as you need it.
When I started learning, I just picked a project, sat down and started trying to code. When I ran into something I didn't know, I just googled it, which led to a tutorial and/or the relevant page of Apple's documentation.
In my experience, the best way to learn something like this is, well, experience.
Apple's documentation generally contains excellent API references, but (in my opinion) lacks equivalent topical guides. This makes it a bit hard to follow for beginners (Jacob Kaplan-Moss in the link I just gave makes the point that Python's documentation is like this, but I think Apple's is much more).
My recommendation would be to pick up Hillegass's book, alongside a project. The first few chapters explain fundamentals, so make sure to read those (and do the exercises!), or you won't be able to get far. Then try and implement your project idea; when you reach a wall, look through the Table of Contents and the glossary of the book and see if there's something that covers it. If you find something, use this as an excuse to read it fully and understand it. When you're finished, you'll have both a greater understanding and a project to show for it. Furthermore, you'll know what to search for in Apple's API references next time you try to implement something. This helped motivate me to finish the book, maybe it'll be helpful for you.[1]
[1]: (disclaimer: I have an odd learning style)

How to learn C and Objective-C [closed]

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I am learning programming. I plan on learning C and Objective-C this summer. I bought the C for Dummies book but it is a complete waste of time. It's way too many pages! Are there any good books I should read? Or should I just learn C from websites? What would be the fastest way because I really want to learn it fast and start learning Objective-C too.
Thank you
Also, how long does it take to learn C? Until I move to Objective-C 2.0
There's no need to rush. Learn at your own pace and find your optimal way of learning.
If reading is your thing, then try to read some books and take it slowly.
If you find a concept you grasp, practice. If you find a concept that you don't quite get, experiment. Once you think you understand the concept, try re-reading the material to see if you understand it the second time.
I found out that I wasn't really good at learning though books -- I generally had to get the first kick-start with a structured lessons in a classroom. A semester course at a community college on Java was able to nudge in the direction of being able to begin effectively learning on my own. See if there are any programming courses offered in your school.
(Although at your age it may be a little bit difficult to find -- I didn't get any formal classes until community college -- my high school did not offer any programming courses.)
One of the things to be careful of is learning it the wrong way.
Rushing through material, or reading poorly written, inaccurate learning material can lead to a situation where you'll need to "un-learn" the concepts and re-learn it the right way.
In that respect, the K&R book (The C Programming Language by Kernighan and Ritchie) would be the "right way" of learning, but it's not a very approachable book. That isn't to say that it is the definitive book on C -- but even after programming in C for a couple years, I still try to take read it a bite-size at a time.
But then again, I can't really think of other "great" sources for learning C. My recommendation would be to take a look at K&R and work on a few pages at a time. Don't think about reading it like a regular book -- read one section, try it out. Do it little-by-little. Once again, don't rush. Work at your own speed.
And be sure to write code. Without seeing it working, it's going to be difficult to learn programming. And don't have huge expectations at first, as most of learning C at the beginning will involve programs that deal with only text.
Once you get a handle of things, try to write clean code that is readable by others -- that should be a motivation to write clean and clear code, and it will force you to think harder about what you're doing.
It's going to be a long adventure, so take it a step at a time. Good luck!
For learning C, I highly recommend Learn C on the Mac, by Dave Mark. Not only is it aimed at beginners, but it also teaches you a lot about the important fundamentals of programming and computer science (e.g. data structures, recursion, etc.). It's very accessible, well-written, and easy to read. Plus, I found the examples engaging and interesting to work with. After that, if you really want to solidify your foundations in C, I'd recommend trying to moving on to The C Programming Language. It's a challenging book, so take it slowly. If you find yourself having too much trouble with it, I'd say you can just skip to Objective-C, and then come back to The C Programming Language later, once you've gained more familiarity with programming in general.
A lot of people will probably recommend The C Programming Language (a.k.a. "K&R") as your first book to read on C. No doubt it is a very well-written C book (and it's short too—only around 200 pages), but I'd say it'd be a little intimidating as a 12-year-old's first exposure to C: it's pretty dense and hardcore. You can tell that it's definitely aimed at an older audience with a strong background in computers/engineering. But nevertheless, if you already know the basics of programming, reading K&R will give you invaluable insight and understanding of C. You should definitely read it at some point in your programming endeavors.
Anyways, for Objective-C, if there's only one book I could recommend, it would most definitely be Cocoa Programming for Mac OS X, by Aaron Hillegass. It's really not that long (~400 pages or so, although I'd reckon that a lot of that is due to the number of illustrations in the book), and you can get some pretty cool projects up and running in an afternoon. It's very clear and easy to read, the examples are practical and interesting to follow, but most importantly, it's got this right blend of not being too intimidating while still managing to provide you with solid information. Plus, it'll teach you more than just Objective-C: I found that I had learned some very useful design patterns, for example, by learning how some of the components of Cocoa worked.
When I look at the title of this question, I am guessing you are 12.
I started programming when I was 13 (I am now 14).
I found that learning depends on what kind of a learner you are!
I hate reading, I have the attention span of a moth and I learn best from videos. Therefor, I am a "visual learner". Try to find out what kind of "learner" you are, then do it that way. Remember, the easiest way is the fastest.
PS, here is a little tip. It may be frustrating (aseptically at our age). If you get frustrated, just put it down for like 10 minutes. Then come back and do research on what your learning. Programming WILL get very frustrating at times.
EDIT:
By the way, I like to learn through video :p
Stanford University posts online the lectures, class notes, and assignments for CS193P (an iPhone development class). If you don't know C or Objective-C at all, it might be tough, but I highly recommend this if you intend to do iPhone development.
I think I've read every Cocoa and Objective-C book out there, and most enjoyed Aaron Hillegass' Cocoa Programming for Mac OS X.
I would take a look at The C Programming Language (K&R C). It's much less than 1000 pages and I think you'll find it well worth your while. As htw said, books do serve a purpose in that they provide a thorough and structured approach. K&R C in particular will give you real insight directly from the creators of C.
That's not to say you shouldn't Google things, read open source code, write little practice programs, etc. It all helps. Just remember to be patient. There's a lot out there.
Checkout out http://www.cprogramming.com/ or and online K&R type book
Don't be impatient; take your time. Follow tutorials, dissect short snippets of code, you'll get the hang of the language. Most importantly, write code yourself and learn from your bugs/errors.And follow Stack Overflow ;)
I've been where you are. It wasn't fun. This is what saved me:
(Apparently new users aren't allowed to post hyperlinks, so google for "steve summit C", use either the first or the third link, and then click "introductory C programming class notes")
It's a C class by a guy named Steve Summit. Super easy to follow, much easier than K&R, imo.
Also, it's free, and there aren't any ads. I loved it. It's how I learned C. I hope it'll do the same for you.
There is nothing so educational as a piece of code you can run and tweak. Code examples in books can be really bland and not very applicable. The exception to this rule was the Perl Cookbook which is jammed packed with really useful little snippets for your perl programs.
The topics (or 'idioms') in it were so useful and so applicable across languages that some smart folks have taken to replicating them in different languages. Each has a varied level of completeness, but it's interesting to see how different languages do the same things.
Take a look here http://pleac.sourceforge.net/ for nuggets of programming wisdom that you can shake a stick at. At the very least its interesting to see how simple things written in one language require reams of code in another.
Were I starting to learn programming again I would probably pick something easy and forgiving, a dynamic language, like Python, Ruby etc. Once you get your head around the basics in one of these (flow control, data structures etc) it will make learning C/Objective-C so much easier. Also you'll find that you'll want to write once-off tools and scripts to help you in your Objective-C development that would be tedious and time consuming to write in C but are a matter of lines in a modern dynamic language. Never hurts to have another tool in your belt.
Good luck
Honestly, I learned Java as my first programming language (I discovered it in high school and decided programming was fun and it was what i wanted to do)
I just now picked up Obj-C in a few weeks, reading a little bit from some books, but not a whole book, and using the internet a lot if i can't figure out the syntax (format/grammar of how the program should be structured and written) for something etc.
How fast you can pick up a language depends on how much you understand the fundamentals of programming. You will only get better at it with time and practice.
If you can understand the fundamentals of programming in general then you should be able to apply it to any language, the hard part is learning and remembering the syntax of different languages. Like in Java, you don't have to do memory allocations, but in C, C++ and Obj-C you do. I've never written a C or C++ program, but now that I've learned and written some programs in Obj-C (i've been making iPhone stuff, it is fun) I'm sure I could pick up C and C++ like it's nothing.
You don't have to learn C first in order to learn Obj-C is what i'm trying to say. But it never hurts to know multiple languages.
It is all about your level of understanding how a program works, how to structure one. I love objective-C because it is Object Oriented like Java so it was easier for me to understand and learn quickly, just had to get used to some of the differences in syntax
(I'm also getting close to graduating from college now so I'm surrounded by programming stuff, from procedural languages like ada to object oriented like java, and knowing the nitty gritty behind the scenes stuff that makes a program work, so understanding and learning a new language has gotten a lot easier for me, you start seeing how they relate and don't relate and it is cool)
It is great that you are starting so young. I'm sure you'll pick up on this stuff real fast, and if it is something you really enjoy, it will be even easier.
Good Luck! and have fun! programming can be so frustrating... like, spending 3 hours debugging when you find out it was because you if statement used a grater than instead of grater than or equal too or something like that. but, once you are done with the program, it is so rewarding, and then you just want to make it better and better haha.
I dunno if this helped at all, I hope it did, somehow...
=)
the way i learned quickest was to watch short video tutorials.
If you really want to start with C, I would start by just reading the first three or so chapters of C for Dummies, just to get a feel for how the language works. After that, I recommend going through web tutorials. Good web tutorials will have short code that explain specific functions, and the like.
As a 13-year old, though, I recommend starting with PHP. It's a simpler language to learn than C, but it's based off of C, so it won't be hard to make the transition, whenever you do so.
Different people have different preferred ways of learning. You can see that in the variety of responses above.
So how do you like to learn? Do you like to sit by yourself with a book and a computer? Do you like to sit in a classroom and absorb learning? Do you prefer set exercises, or mini-projects?
When I learn new programming languages, I find it helps me if I have a small application or problem to work on. I prefer to have a problem to work on. If you have a little project of your own that you always wanted to do, use that. If not, as someone above suggested, join a robotics group. Set up a web page and write some programs to do stuff for that.
Look on the web for programming challenges. Google has a fun one every year.
If you want an idea, write a sukoku checking program. Then later, write a sudoku solver!
I like to use a variety of books, rather than just sticking to one or two of the ones suggested above. Find a book whose style you like. Try a few from the library until you find one or two that really click for you.
Personally, I like O'Reilly Publishing books for their chatty and readable style. I learnt C from Deitel, which is more of a classroom style textbook, but it has lots of examples and discussion points.
As you work through examples on your computer, you might wonder how things change if you tweak the code. I learn a lot by first running the example code suggested in a text, but then changing it to see what happens. If I get what I expect, it's a sign that my understanding is pretty good. If I get something unexpected, I try to figure out how I misunderstood what I did.
One last suggestion. Why not start with Python rather than C? I hear that a lot of schools are teaching Python to their kids. The reasons I suggest this are:
Python is pretty easy. You don't have to lay out memory, declare variables and such. No tedious bookkeeping.
Python gives you a nice growth path. You can start off just writing script style programs, using the built in types like lists and dictionaries. Then you progress to using new modules as you need them, and advance into object-oriented coding using classes. There's some functional programming stuff in there too, which you can start learning once you have the basic mechanics of the language under control.
I just love visiting new parts of python all the time.
You can get a lot done in python. It comes with a whole lot of built in modules to do almost anything you like - email, web, xml, graphics, gui, etc.
:)
When I was learning to program in C, I found that Practical C Programming was a good resource. It's a very approachable book with lots of examples.
The fastest way in my view is through learn through websites.
Set a goal of what you want to do and start a simple project
Instead of reading too many books theoretically,google what you want to know to get it instantly as you go through your project.This way you get PRACTICAL knowledge.
Watch online videos as well.Check out my question on VIDEOS here
Ask whatever you don't understand on stackoverflow. We're here to help :)
Follow these steps and I can assure you that you will be a great programmer soon!
Cheers!
With others, I highly recommend Kernighan and Ritchie—perhaps the best language book ever written. I'd also recommend that you slow down and enjoy yourself: don't be wide and shallow; start out narrow and deep. If you like programming, you will want to master the craft rather than be in a hurry. This essay by Peter Norvig explains how not to be in such a rush.
P.S. I started programming at age 12 with APL/360. I had a blast and have been doing it ever since—35 years and counting. Good luck and don't forget to have fun!
By far the best way (and usually the fastest) to learn programming is to find a good mentor. That's easier said than done. But I think you'd be surprised how many people would be willing to help you out. My advice would be just don't be afraid to ask.
If I were you I would find a local FIRST robotics team and see if you can hang out for some of the coding. Odds are you'll be working on a similar problem and will have some support from people who have a decent amount of experience. That's what I would have done, anyway.
I started learning to program in Basic in about 1981 when I was 10. Not many years later it was 6502 assembly to try to get more speed out of a 1 MHz Apple IIe clone.
Pascal was a revelation in 1988 - programming without line numbers.
Modula-2, C, Eiffel, Miranda, Haskel, and Prolog at university as well as scripting in any number of languages.
C++ professionally for about 6 years.
C#, then Java, Ruby, and now back to C# for the last 18 months.
Python somewhere along the way.
My advice, pick the language that is best suited to the problem you need to solve today.
The first problem you have is to learn the basics ie how to break down a problem and express it in a clear and concise manner. I suggest you choose something other than C. I recommend Python as the online documentation is excellent and the libraries are great and you will spend more time writing interesting code and less time trying to figure out why your code stopped due to a segmentation fault.
When you've got the basic concepts under your belt, try some assembly and learn what's going on under the hood. If nothing else, you'll learn how fast CPUs really are. C is a good step after that. I also suggest you try Java or C# before Objective-C.
As to how long before moving to Objective-C, it really depends on how talented you are. If you're really good, then once you've learnt your 3rd or 4th language you'll can be more productive than most coders within 6 weeks of starting a new language (although changing language families (ie imperative, functional, object oriented) takes longer). If you're no good then don't expect to get past the first. Hopefully you make it into the first category.
In addition to whatever books and websites you end up using, you might consider looking around your area for local support groups. Many areas have a Linux user group or a group for Java or Ruby programming. Professional programmers use these groups to help each other with their programming problems, but the groups are generally friendly to young people and beginners. Don't feel embarrassed or awkward because of your age and inexperience. Most people will admire your initiative and curiosity and be happy to help you when you run into problems.
Assuming you have some basic programming knowledge, Cocoa Dev Central have a series of articles that explain basic C then Objective-C, in a somewhat-less-than-1000-pages way..
Learn C for Cocoa, then Learn Objective-C
Shouldn't take even an hour to go through. The articles don't cover anything remotely advanced, but if you're learning ObjC to write OS X applications, the ObjC bit is basically trivial, it's Cocoa that is difficult to learn!
If you want to learn Objectif-C to create iPhone application, don't waste your time on C and learn Objectif-C now, then a book on iPhone programming. It will be more than 1000 pages but if you want to program in your life, you have to be used to read these types of book.
I created an online interactive C tutorial, you can start using it without installing an IDE.
http://www.learn-c.org