Search Results

Search found 4685 results on 188 pages for 'cpp beginner'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 47/188 | < Previous Page | 43 44 45 46 47 48 49 50 51 52 53 54  | Next Page >

  • Java - How to declare table[i][j] elements as instance variables?

    - by JDelage
    All, I am trying to code a Connect4 game. For this, I have created a P4Game class and a P4Board class which represents the i X j dimensions of the Connect4 board. In P4Game, I have the following: public class P4Game{ //INSTANCE VARIABLES private int nbLines; private int nbColumns; private P4Board [][] position; //CONSTRUCTOR public P4Game(int nbLines, int nbColumns){ this.nbColumns = nbColumns; this.nbLines = nbLines; P4Board [][] position = new P4Board [nbLines][nbColumns]; //Creates the table to receive the instances of the P4Board object.*/ for (int i=0; i<nbLines; i++){ for (int j=0; j<nbColumns; j++){ this.position[i][j] = new P4Board(i,j); //Meant to create each object at (line=i, column=j) } } } This causes a NullPointerException in the nested loops where I mention this.position[i][j]. I reference those objects in other methods of this class so I need them to be instance variables. I suppose the exception is due to the fact that I have not listed the table element position[i][j] as an instance variable at the beginning of the class. my question to people here is (1) is my assumption correct, and if so (2) what would be the syntax to declare instance variables of this form? Thank you all for your help with what I realize is a very basic question. Hopefully it will also benefit other newbies. Cheers, JDelage

    Read the article

  • Getting started with microcontroller programming

    - by Trix
    I'm a fairly good programmer, knowledgeable in C, C++, Python, Ruby and PHP. I'd like to get started with microcontroller programming. I do know nothing about this topic. Microcontrollers are minimal computers on little circuit boards, right? I'm pretty new to electronics too, do I need to be an expert in it to do stuff with microcontrollers? What can I do with them? Would e.g.: A Pacman or Tetris game on an LCD be possible and not too hard? Where should I start? Basically I want to program something really small I can then take with me. This is my only real goal. Are microcontrollers the right thing for this, or are there better solutions? I'd like to do this for fun and as a hobby, I don't want to become a professional in it.

    Read the article

  • Restore previously serialized JFrame-object, how?

    - by elementz
    Hi all. I have managed to serialize my very basic GUI-object containing a JTextArea and a few buttons to a file 'test.ser'. Now, I would like to completely restore the previously saved state from 'test.ser', but seem to have a misconception of how to properly deserialize an objects state. The class MyFrame creates the JFrame and serializes it. public class MyFrame extends JFrame implements ActionListener { // Fields JTextArea textArea; String title; static MyFrame gui = new MyFrame(); private static final long serialVersionUID = 1125762532137824262L; /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub gui.run(); } // parameterless default contructor public MyFrame() { } // constructor with title public MyFrame(String title) { } // creates Frame and its Layout public void run() { JFrame frame = new JFrame(title); JPanel panel_01 = new JPanel(); JPanel panel_02 = new JPanel(); JTextArea textArea = new JTextArea(20, 22); textArea.setLineWrap(true); JScrollPane scrollPane = new JScrollPane(textArea); scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED); panel_01.add(scrollPane); // Buttons JButton saveButton = new JButton("Save"); saveButton.addActionListener(this); JButton loadButton = new JButton("Load"); loadButton.addActionListener(this); panel_02.add(loadButton); panel_02.add(saveButton); // Layout frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(BorderLayout.CENTER, panel_01); frame.getContentPane().add(BorderLayout.SOUTH, panel_02); frame.setSize(300, 400); frame.setVisible(true); } /* * */ public void serialize() { try { ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("test.ser")); oos.writeObject(gui); oos.close(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } public void actionPerformed(ActionEvent ev) { System.out.println("Action received!"); gui.serialize(); } } Here I try to do the deserialization: public class Deserialize { static Deserialize ds; static MyFrame frame; public static void main(String[] args) { try { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.ser")); frame = (MyFrame) ois.readObject(); ois.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

    Read the article

  • K&R Exercise 1-21 - Mental incomprehension.

    - by asdfg
    The "impossible" K&R exercise. "Write a program entab that replaces strings of blanks by the minimum number of tabs and blanks to achieve the same spacing. Use the same tab stops, say every n columns. Should n be a variable or a symbolic parameter?" The problem I'm having is, I'm unsure about how to even do this correctly. I know it's not very explanatory, but that's pretty much the problem here. Most of the examples I've seen have counted a number of blanks, and replaced those series with a tab, but this isn't what its asking, I reckon I understand what its asking, but currently feel unable to do this. Could anyone help :)

    Read the article

  • Using an ampersand in scanf()

    - by Rob
    When I compile scanf("%s", &var);, gcc sends back a warning: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char (*)[20]’ however when I compile scanf("%s", var);, no warning is applied. Both pieces of code work and the book I am reading specifically says to use the ampersand, but even it doesn't in some of the examples. My question is, should I continue to use the ampersand, even when the book doesn't specify?

    Read the article

  • Java: initialization problem, cannot print "assigned" values from arrayList

    - by HH
    $ javac ArrayListTest.java $ java ArrayListTest $ cat ArrayListTest.java import java.io.*; import java.util.*; public class ArrayListTest{ public static void main(String[] args) { try { String hello ="oeoaseu oeu hsoae sthoaust hoaeut hoasntu"; ArrayList<String> appendMe = null; for(String s : hello.split(" ")) appendMe.add(s+" "); for(String s : appendMe) System.out.println(s); //WHY DOES IT NOT PRINT? }catch(Exception e){ } } }

    Read the article

  • Getting a cryptic error on my simple Java program, comparing char[i] to a string.

    - by Sergio Tapia
    public static void ejemplosString(String palabra){ char[] letras = palabra.toCharArray(); int contadorVocales = 0; for (int i = 0; i < letras.length; i++) { if (char[i] == 'a') { contadorVocales++; } if (char[i] == "e") { contadorVocales++; } if (char[i] == "i") { contadorVocales++; } if (char[i] == "o") { contadorVocales++; } if (char[i] == "u") { contadorVocales++; } } } Getting the error on every If statement. Any guidance?

    Read the article

  • importing class and its function from another file

    - by user343934
    Hi everyone, I am having little problem with importing classes in python. My work flow goes like this index.py class Template: def header(): def body(): def form(): def footer(): display.py I want to call function header(), body() and footer () in my display.py page. Will anyone make me clear about this issue in python. Thanks for your concern.

    Read the article

  • taking integer input in java

    - by ruchir patwa
    I am actually new to java programming and am finding it difficult to take integer input and storing it in variables...i would like it if someone could tell me how to do it or provide with an example like adding two numbers given by the user..

    Read the article

  • Error in Python's os.walk?

    - by Mike Caron
    The os.walk documentation (http://docs.python.org/library/os.html? highlight=os.walk#os.walk), says I can skip traversing unwanted directories by removing them from the dir list. The explicit example from the docs: import os from os.path import join, getsize for root, dirs, files in os.walk('python/Lib/email'): print root, "consumes", print sum(getsize(join(root, name)) for name in files), print "bytes in", len(files), "non-directory files" if 'CVS' in dirs: dirs.remove('CVS') # don't visit CVS directories I see different behavior (using ActivePython 2.6.2). Namely for the code: >>> for root,dirs,files in os.walk(baseline): ... if root.endswith(baseline): ... for d in dirs: ... print "DIR: %s" % d ... if not d.startswith("keep_"): ... print "Removing %s\\%s" % (root,d) ... dirs.remove(d) ... ... print "ROOT: %s" % root ... I get the output: DIR: two Removing: two DIR: thr33 Removing: thr33 DIR: keep_me DIR: keep_me_too DIR: keep_all_of_us ROOT: \\mach\dirs ROOT: \\mach\dirs\ONE ROOT: \\mach\dirs\ONE\FurtherRubbish ROOT: \\mach\dirs\ONE\FurtherRubbish\blah ROOT: \\mach\dirs\ONE\FurtherRubbish\blah\Extracted ROOT: \\mach\dirs\ONE\FurtherRubbish\blah2\Extracted\Stuff_1 ... WTF? Why wasn't \\mach\dirs\ONE removed? It clearly doesn't start with "keep_".

    Read the article

  • Java: print field in an image of other class?

    - by HH
    DirectoryReader.java public class DirectoryReader { public static void main(String[] args) { File myFile = new File(path); FileObject fileThing = new FileObject(myFile); //How to print the value of the hello-field from fileThing? } } FileObject.java public class FileObject { FileObject (File fileThing) { String hello = "Hello Cosmos!"; } }

    Read the article

  • How do you calculate accumulative time in C#?

    - by lima
    I want to calculate the time span between 2 times which I saved in a database. So literally I want to know the length of time between the 2 values. 14:10:20 - 10:05:15 = 02:05:05 So the result would be 02:05:05. How would I be able to achieve this using C#? 14:10:20 is the format I saved it in in my database.

    Read the article

  • Difference in Django object creation call

    - by PhilGo20
    I'd like to know if there's a difference between the following two calls to create an object in Django Animal.objects.create(name="cat", sound="meow") and Animal(name="cat", sound="meow") I see both in test cases and I want to make sure I am not missing something. thanks

    Read the article

  • How to use SQLite3 with Java

    - by Bruce
    I am trying to build a simple java program which creates a db file, then a table and inserts dummy values in the table. I found this page http://www.zentus.com/sqlitejdbc/index.html and tried out the example given on the page but I am getting the following error - Exception in thread "main" java.lang.NoClassDefFoundError: Test Caused by: java.lang.ClassNotFoundException: Test at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) Could not find the main class: Test. Program will exit.

    Read the article

  • Running iPython from the OSX terminal.

    - by Az
    So I'm going through the matplotlib documentation and prepared to use the iPython interactive Python shell with ipython -pylab. However I get this: Az's MBP:~ Az$ ipython -pylab -bash: ipython: command not found Did I fail to install iPython? I used easy_install as advised. Any ideas?

    Read the article

  • accing a fortran 'module' in a 'function defined in some other file

    - by cppb
    hello, I am using fortran 90 I have defined a fortran module in fileA.f as: module getArr double precision a(100) end module getArr The same fileA.f contains a subroutine that uses this module subroutine my_sub use getArr implicit none getArr%a(1) = 10.5 end subroutine In fileB.f, I have a fortrtan function. I am trying to access the value of getArr%a(1) as: double precision function my_func(R) use getArr double precision x x = getArr%a(1) return end But I am getting errors at the compile time. It says it is unable to access the module getArr. How should I declare it?? Thanks

    Read the article

  • How to generate graphs and statistics from SQLAlchemy tables [Python]?

    - by Az
    Hi all, After running a bunch of simulations I'm going to be outputting the results into a table created using SQLAlchemy. I plan to use this data to generatw statistics - mean and variance being key. These, in turn, will be used to generate some graphs - histograms/line graphs, pie-charts and box-and-whisker plots specifically. I'm aware of the Python graphing libraries like matplotlib. The thing is, I'm not sure how to have this integrate with the information contained within the database tables. Any suggestions on how to make these two play with each other? The main problem is that I'm not sure how to supply the information as "data sets" to the graphing library. Thanks in advance.

    Read the article

  • Active Record like functionality on array instance variable

    - by rube_noob
    I would like to write a module that provides active record like functionality on an array instance variable. Examples of its use would be x = Container.new x.include(ContainerModule) x.elements << Element.new x.elements.find id module ContainerModule def initialize(*args) @elements = [] class << @elements def <<(element) #do something with the Container... super(element) end def find(id) #find an element using the Container's id self #=> #<Array..> but I need #<Container..> end end super(*args) end end The problem is that I need the Container object within these methods. Any reference to self will return the Array, not the Container object. Is there any way to do this? Thanks!

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 43 44 45 46 47 48 49 50 51 52 53 54  | Next Page >