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  • Why is this an invalid Turing machine?

    - by Danny King
    Whilst doing exam revision I am having trouble answering the following question from the book, "An Introduction to the Theory of Computation" by Sipser. Unfortunately there's no solution to this question in the book. Explain why the following is not a legitimate Turing machine. M = { The input is a polynomial p over variables x1, ..., xn Try all possible settings of x1, ..., xn to integer values Evaluate p on all of these settings If any of these settings evaluates to 0, accept; otherwise reject. } This is driving me crazy! I suspect it is because the set of integers is infinite? Does this somehow exceed the alphabet's allowable size? Thanks!

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  • trying to find a web service

    - by sbsp
    i am trying to find a web service that allows a user to send a company name (or better still will return a list of all company names, thus allowing the user to select one) and then get the share price, this will then feed in to another api - yahoo currency converter to work out the price of the share the issue i am having is that i cannot find a web service to get share info, google registration for theres does not seem to be working and as such i dont no what to do i am to be coding this in php if anyone could point me to a good web service i would appreciate it thanks edit : i did find this but am unsure if it is appropriate http://www.xignite.com/xGlobalQuotes.asmx?WSDL

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  • Custom Windows Forms Control not exporting functions, not showing in tools list, showing as Text

    - by flavour404
    Hi, I have written a very simple control. C# Visual Studio 2008. Its output should be, and is a dll. I have added a reference to the dll within the project that I intend to use it with. The msdn article about how to write a control states that it should appear in the 'Add reference / projects' list, which it doesn't but I simply navigated to it under the 'browse' tab, went to the /bin folder and added the reference that way. I dragged it over to my toolbox, but it shows up as a 'Text:xhair_tool' and when i try and add it to a form, it won't, so what have I done wrong? It was created as a 'Windows forms control' project. It should export the one method which is 'Target' which return an array, as shown below. using System; using System.Collections.Generic; using System.ComponentModel; using System.Drawing; using System.Data; using System.Text; using System.Windows.Forms; namespace xhair_tool { public partial class xhair : UserControl { public xhair() { InitializeComponent(); } private void xhair_Load(object sender, EventArgs e) { } protected override void OnPaint(PaintEventArgs e) { Graphics g = e.Graphics; Pen pen = new Pen(Color.Black, 1); SolidBrush redBrush = new SolidBrush(Color.Red); g.DrawLine(pen, 8, 0, 8, 7); g.DrawLine(pen, 8, 9, 8, 16); g.DrawLine(pen, 0, 8, 7, 8); g.DrawLine(pen, 9, 8, 16, 8); //ControlPaint.DrawReversibleLine(start, end, backColor) } /// <summary> /// Returns the point at the center of the crosshair /// </summary> /// <returns>int[x,y]</returns> public int[] Target { get { int[] _xy = new int[2]; _xy[0] = this.Left + 8; _xy[1] = this.Top + 8; return _xy; } } } } Thanks, R.

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  • read file in C++

    - by Amm Sokun
    I am trying to read a list of words from a file in C++. However, the last word is read twice. I cannot understand why it is so. Can someone help me out? int main () { ifstream fin, finn; vector<string> vin; vector<string> typo; string word; fin.open("F:\\coursework\\pz\\gattaca\\breathanalyzer\\file.in"); if (!fin.is_open()) cout<<"Not open\n"; while (fin) { fin >> word; cout<<word<<endl; vin.push_back(word); } fin.close(); }

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  • bash : recursive listing of all files problem

    - by Michael Mao
    Run a recursive listing of all the files in /var/log and redirect standard output to a file called lsout.txt in your home directory. Complete this question WITHOUT leaving your home directory. An: ls -R /var/log/ /home/bqiu/lsout.txt I reckon the above bash command is not correct. This is what I've got so far: $ ls -1R .: cal.sh cokemachine.sh dir sort test.sh ./dir: afile.txt file subdir ./dir/subdir: $ ls -R | sed s/^.*://g cal.sh cokemachine.sh dir sort test.sh afile.txt file subdir But this still leaves all directory/sub-directory names (dir and subdir), plus a couple of empty newlines How could I get the correct result without using Perl or awk? Preferably using only basic bash commands(this is just because Perl and awk is out of assessment scope)

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  • C code autocomplete in Eclipse

    - by Ittai
    Hi, I'm a Java developer and I've downloaded the Eclipse for C (course purposes) and to my amazement the control+space shortcut (for autocomplete) did not work. I've created a new project and a new class using the wizzards and started to type "print" and then tried to find an autocomplete feature. After a bit of googling I arrived at C/C++-Editor-Content Assist-Advanced and there I verified that Help proposals,Parsing-based proposals and Template proposals options were checked. I then went over to the Keys preferences page using the link at that page and entered a binding for all relevant content assist from before C\C++ Content Assist (type...) and chose in the When box the C\C++ Editor option. But alas no autocompletion was offered. Can someone please point me to the right direction? Thanks, Ittai

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  • Problem passing strings with PHP post

    - by andy
    Hi Guys, Basically I'm developing a (very) simple search engine. You can enter a search term and you are taken to the results page - which works fine. However on the results page, I have a button that will take you to the next 10 results: where $term is the $_POST['term'] value. echo "<input type='hidden' name='term' value='" . $term . "'>"; This causes the following problem with the term is for example "aidan's". When the next 10 button is clicked, the term becomes aidan\ and no further results are found. I am not doing anything to $term. I usually use Java, but am required to use PHP for this uni assignment! Any help would be greatly appreciated.

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  • Neural Network Always Produces Same/Similar Outputs for Any Input

    - by l33tnerd
    I have a problem where I am trying to create a neural network for Tic-Tac-Toe. However, for some reason, training the neural network causes it to produce nearly the same output for any given input. I did take a look at Artificial neural networks benchmark, but my network implementation is built for neurons with the same activation function for each neuron, i.e. no constant neurons. To make sure the problem wasn't just due to my choice of training set (1218 board states and moves generated by a genetic algorithm), I tried to train the network to reproduce XOR. The logistic activation function was used. Instead of using the derivative, I multiplied the error by output*(1-output) as some sources suggested that this was equivalent to using the derivative. I can put the Haskell source on HPaste, but it's a little embarrassing to look at. The network has 3 layers: the first layer has 2 inputs and 4 outputs, the second has 4 inputs and 1 output, and the third has 1 output. Increasing to 4 neurons in the second layer didn't help, and neither did increasing to 8 outputs in the first layer. I then calculated errors, network output, bias updates, and the weight updates by hand based on http://hebb.mit.edu/courses/9.641/2002/lectures/lecture04.pdf to make sure there wasn't an error in those parts of the code (there wasn't, but I will probably do it again just to make sure). Because I am using batch training, I did not multiply by x in equation (4) there. I am adding the weight change, though http://www.faqs.org/faqs/ai-faq/neural-nets/part2/section-2.html suggests to subtract it instead. The problem persisted, even in this simplified network. For example, these are the results after 500 epochs of batch training and of incremental training. Input |Target|Output (Batch) |Output(Incremental) [1.0,1.0]|[0.0] |[0.5003781562785173]|[0.5009731800870864] [1.0,0.0]|[1.0] |[0.5003740346965251]|[0.5006347214672715] [0.0,1.0]|[1.0] |[0.5003734471544522]|[0.500589332376345] [0.0,0.0]|[0.0] |[0.5003674110937019]|[0.500095157458231] Subtracting instead of adding produces the same problem, except everything is 0.99 something instead of 0.50 something. 5000 epochs produces the same result, except the batch-trained network returns exactly 0.5 for each case. (Heck, even 10,000 epochs didn't work for batch training.) Is there anything in general that could produce this behavior? Also, I looked at the intermediate errors for incremental training, and the although the inputs of the hidden/input layers varied, the error for the output neuron was always +/-0.12. For batch training, the errors were increasing, but extremely slowly and the errors were all extremely small (x10^-7). Different initial random weights and biases made no difference, either. Note that this is a school project, so hints/guides would be more helpful. Although reinventing the wheel and making my own network (in a language I don't know well!) was a horrible idea, I felt it would be more appropriate for a school project (so I know what's going on...in theory, at least. There doesn't seem to be a computer science teacher at my school). EDIT: Two layers, an input layer of 2 inputs to 8 outputs, and an output layer of 8 inputs to 1 output, produces much the same results: 0.5+/-0.2 (or so) for each training case. I'm also playing around with pyBrain, seeing if any network structure there will work. Edit 2: I am using a learning rate of 0.1. Sorry for forgetting about that. Edit 3: Pybrain's "trainUntilConvergence" doesn't get me a fully trained network, either, but 20000 epochs does, with 16 neurons in the hidden layer. 10000 epochs and 4 neurons, not so much, but close. So, in Haskell, with the input layer having 2 inputs & 2 outputs, hidden layer with 2 inputs and 8 outputs, and output layer with 8 inputs and 1 output...I get the same problem with 10000 epochs. And with 20000 epochs. Edit 4: I ran the network by hand again based on the MIT PDF above, and the values match, so the code should be correct unless I am misunderstanding those equations. Some of my source code is at http://hpaste.org/42453/neural_network__not_working; I'm working on cleaning my code somewhat and putting it in a Github (rather than a private Bitbucket) repository. All of the relevant source code is now at https://github.com/l33tnerd/hsann.

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  • SQL where clause to work with Group by clause after performing a count()

    - by Matt
    Tried my usual references at w3schools and google. No luck I'm trying to produce the following results. QTY is a derived column | Position | QTY -------------------- 1 Clerk 2 2 Mgr 2 Here's what I'm not having luck with: SELECT Position, Count(position) AS 'QTY' FROM tblemployee Where ('QTY' != 1) GROUP BY Position I know that my Position is set up as varchar(255) Count produces a integer data and my where clasue is accurate so that leads me to believe that that Count() is jamming me up. Please throw up an example so I can reference later. Thanks for the help!

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  • Theory of computation - Using the pumping lemma for context free languages

    - by Tony
    I'm reviewing my notes for my course on theory of computation and I'm having trouble understanding how to complete a certain proof. Here is the question: A = {0^n 1^m 0^n | n>=1, m>=1} Prove that A is not regular. It's pretty obvious that the pumping lemma has to be used for this. So, we have |vy| = 1 |vxy| <= p (p being the pumping length, = 1) uv^ixy^iz exists in A for all i = 0 Trying to think of the correct string to choose seems a bit iffy for this. I was thinking 0^p 1^q 0^p, but I don't know if I can obscurely make a q, and since there is no bound on u, this could make things unruly.. So, how would one go about this?

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  • assembly language programming (prime number)

    - by chris
    Prompt the user for a positive three digit number, then read it. Let's call it N. Divide into N all integer values from 2 to (N/2)+1 and test to see if the division was even, in which case N is instantly shown to be non-prime. Output a message printing N and saying that it is not prime. If none of those integer values divide evenly (remainder never is zero), then N is shown to be prime. Output a message printing N and saying that it is prime. Ask the user if he or she wants to test another number; if the user types "n" or "N", quit. If "y" or "Y", jump back and repeat. Comments in your code are essential. Hi. I am kinda in rush to do this.. please help me doing it. I'll be much appreciated. thank you

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  • Counting the number of characters in a file

    - by Kat
    I'm writing a program that for one part asks for the program to print how many characters (including whitespaces) are in a file. The code I have right now though returns 0 every time though and I'm not sure why it isn't counting the characters. public int getcharCount(Scanner textFile) { int count = 0; while(textFile.hasNext()) { String line = textFile.nextLine(); for(int i=0; i < line.length(); i++) count++; } return count; }

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  • Finding the heaviest length-constrained path in a weighted Binary Tree

    - by Hristo
    UPDATE I worked out an algorithm that I think runs in O(n*k) running time. Below is the pseudo-code: routine heaviestKPath( T, k ) // create 2D matrix with n rows and k columns with each element = -8 // we make it size k+1 because the 0th column must be all 0s for a later // function to work properly and simplicity in our algorithm matrix = new array[ T.getVertexCount() ][ k + 1 ] (-8); // set all elements in the first column of this matrix = 0 matrix[ n ][ 0 ] = 0; // fill our matrix by traversing the tree traverseToFillMatrix( T.root, k ); // consider a path that would arc over a node globalMaxWeight = -8; findArcs( T.root, k ); return globalMaxWeight end routine // node = the current node; k = the path length; node.lc = node’s left child; // node.rc = node’s right child; node.idx = node’s index (row) in the matrix; // node.lc.wt/node.rc.wt = weight of the edge to left/right child; routine traverseToFillMatrix( node, k ) if (node == null) return; traverseToFillMatrix(node.lc, k ); // recurse left traverseToFillMatrix(node.rc, k ); // recurse right // in the case that a left/right child doesn’t exist, or both, // let’s assume the code is smart enough to handle these cases matrix[ node.idx ][ 1 ] = max( node.lc.wt, node.rc.wt ); for i = 2 to k { // max returns the heavier of the 2 paths matrix[node.idx][i] = max( matrix[node.lc.idx][i-1] + node.lc.wt, matrix[node.rc.idx][i-1] + node.rc.wt); } end routine // node = the current node, k = the path length routine findArcs( node, k ) if (node == null) return; nodeMax = matrix[node.idx][k]; longPath = path[node.idx][k]; i = 1; j = k-1; while ( i+j == k AND i < k ) { left = node.lc.wt + matrix[node.lc.idx][i-1]; right = node.rc.wt + matrix[node.rc.idx][j-1]; if ( left + right > nodeMax ) { nodeMax = left + right; } i++; j--; } // if this node’s max weight is larger than the global max weight, update if ( globalMaxWeight < nodeMax ) { globalMaxWeight = nodeMax; } findArcs( node.lc, k ); // recurse left findArcs( node.rc, k ); // recurse right end routine Let me know what you think. Feedback is welcome. I think have come up with two naive algorithms that find the heaviest length-constrained path in a weighted Binary Tree. Firstly, the description of the algorithm is as follows: given an n-vertex Binary Tree with weighted edges and some value k, find the heaviest path of length k. For both algorithms, I'll need a reference to all vertices so I'll just do a simple traversal of the Tree to have a reference to all vertices, with each vertex having a reference to its left, right, and parent nodes in the tree. Algorithm 1 For this algorithm, I'm basically planning on running DFS from each node in the Tree, with consideration to the fixed path length. In addition, since the path I'm looking for has the potential of going from left subtree to root to right subtree, I will have to consider 3 choices at each node. But this will result in a O(n*3^k) algorithm and I don't like that. Algorithm 2 I'm essentially thinking about using a modified version of Dijkstra's Algorithm in order to consider a fixed path length. Since I'm looking for heaviest and Dijkstra's Algorithm finds the lightest, I'm planning on negating all edge weights before starting the traversal. Actually... this doesn't make sense since I'd have to run Dijkstra's on each node and that doesn't seem very efficient much better than the above algorithm. So I guess my main questions are several. Firstly, do the algorithms I've described above solve the problem at hand? I'm not totally certain the Dijkstra's version will work as Dijkstra's is meant for positive edge values. Now, I am sure there exist more clever/efficient algorithms for this... what is a better algorithm? I've read about "Using spine decompositions to efficiently solve the length-constrained heaviest path problem for trees" but that is really complicated and I don't understand it at all. Are there other algorithms that tackle this problem, maybe not as efficiently as spine decomposition but easier to understand? Thanks.

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  • SwingWorker in Java (beginner question)

    - by Malachi
    I am relatively new to multi-threading and want to execute a background task using a Swingworker thread - the method that is called does not actually return anything but I would like to be notified when it has completed. The code I have so far doesn't appear to be working: private void crawl(ActionEvent evt) { try { SwingWorker<Void, Void> crawler = new SwingWorker<Void, Void>() { @Override protected Void doInBackground() throws Exception { Discoverer discover = new Discoverer(); discover.crawl(); return null; } @Override protected void done() { JOptionPane.showMessageDialog(jfThis, "Finished Crawling", "Success", JOptionPane.INFORMATION_MESSAGE); } }; crawler.execute(); } catch (Exception ex) { JOptionPane.showMessageDialog(this, ex.getMessage(), "Exception", JOptionPane.ERROR_MESSAGE); } } Any feedback/advice would be greatly appreciated as multi-threading is a big area of programming that I am weak in.

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  • substitute in a nested list (prolog)

    - by linda
    /* substitute(X,Y,Xs,Ys) is true if the list Ys is the result of substituting Y for all occurrences of X in the list Xs. This is what I have so far: subs(_,_,[],[]). subs(X,Y,[X|L1],[Y|L2]):- subs(X,Y,L1,L2). subs(X,Y,[H|L1],[H|L2]):- X\=H, not(H=[_|_]), subs(X,Y,L1,L2). subs(X,Y,[H|_],[L2]):- X\=H, H=[_|_], subs(X,Y,H,L2). My code works except it omits the elements following the nested list. For example: ?- subs(a,b,[a,[a,c],a],Z). Z = [b, [b, c]] . What should I add to this program?

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  • Tricky Big-O complexity

    - by timeNomad
    public void foo (int n, int m) { int i = m; while (i > 100) i = i/3; for (int k=i ; k>=0; k--) { for (int j=1; j<n; j*=2) System.out.print(k + "\t" + j); System.out.println(); } } I figured the complexity would be O(logn). That is as a product of the inner loop, the outer loop -- will never be executed more than 100 times, so it can be omitted. What I'm not sure about is the while clause, should it be incorporated into the Big-O complexity? For very large i values it could make an impact, or arithmetic operations, doesn't matter on what scale, count as basic operations and can be omitted?

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  • Unexpected space between DIV elements, no - not padding and not margins

    - by jon
    my code for the php page displaying the divs <?php session_start(); require_once("classlib/mainspace.php"); if (isset($_SESSION['username'])==FALSE) { header("location:login.php"); } $user = new User($_SESSION['username']); ?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="style/style.css" /> <title>SimpleTask - Home</title> </head> <body> <div id="main"> <div id="menu"> <div id="items"> <ul> <li><a href="home.php">home</a></li> <li>&bull;</li> <li><a href="projects.php">my projects</a></li> <li>&bull;</li> <li><a href="comments.php">my comments</a></li> </ul> </div> <div id="user"> <p>Welcome, <?php echo $user->GetRealName(); ?><br/><a href="editprofile.php">edit profile</a> &bull; <a href="logout.php">logout</a></p> </div> </div> <div id="content"> <h1>HOME</h1> </div> <div id="footer"> <p>footer text goes here here here here</p> </div> </div> </body> </html> and you can find my CSS here http://tasker.efficaxdevelopment.com/style/style.css and to view the live page go here http://tasker.efficaxdevelopment.com/login.php username:admin password:password

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  • Theory of computation - Using the pumping lemma for CFLs

    - by Tony
    I'm reviewing my notes for my course on theory of computation and I'm having trouble understanding how to complete a certain proof. Here is the question: A = {0^n 1^m 0^n | n>=1, m>=1} Prove that A is not regular. It's pretty obvious that the pumping lemma has to be used for this. So, we have |vy| = 1 |vxy| <= p (p being the pumping length, = 1) uv^ixy^iz exists in A for all i = 0 Trying to think of the correct string to choose seems a bit iffy for this. I was thinking 0^p 1^q 0^p, but I don't know if I can obscurely make a q, and since there is no bound on u, this could make things unruly.. So, how would one go about this?

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  • Candidate Elimination Question---Please help!

    - by leon
    Hi , I am doing a question on Candidate Elimination Algorithm. I am a little confused with the general boundary G. Here is an example, I got G and S to the fourth case, but I am not sure with the last case. Sunny,Warm,Normal,Strong,Warm,Same,EnjoySport=yes Sunny,Warm,High,Strong,Warm,Same,EnjoySport=yes Rainy,Cold,High,Strong,Warm,Change,EnjoySport=no Sunny,Warm,High,Strong,Cool,Change,EnjoySport=yes Sunny,Warm,Normal,Weak,Warm,Same,EnjoySport=no What I have here is : S 0 :{0,0,0,0,0,0} S 1 :{Sunny,Warm,Normal,Strong,Warm,Same} S 2 , S 3 : {Sunny,Warm,?,Strong,Warm,Same} S 4 :{Sunny,Warm,?,Strong,?,?} G 4 :{Sunny,?,?,?,?,?,?,Warm,?,?,?,?} G 3 :{Sunny,?,?,?,?,?,?,Warm,?,?,?,?,?,?,?,?,?,Same} G 0 , G 1 , G 2 : {?,?,?,?,?,?} What would be the result of G5? Is it G5 empty? {}? or {???Strong??) ? Thanks

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  • Exception Class: When to Derive from it, In C# (.Net)?

    - by IbrarMumtaz
    I am continuing with my exam revision. I have come across the usage of the Base Exception class and I have seen it on exam papers also. My question is when do you derive from the Base Exception class? I am of the impression if you want a custom class to throw an exception with more meaningful information, then you can create a custom exception class that contains the exact data that is representative of how your custom class is used and what scenario it is designed to be used for? Why can't my custom exception class derive from 'ApplicationException' or 'SecurityException' or the base 'Exception' class? I am of the impression that I should derive from the base Exception class and not the previous two. My question second is, when would you derive from the other two??? Are there any clear-cut distinctions as to when you would derive from either one of these three? Assuming there are no others I have I have missed out? Thanks, Ibrar

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  • Implementing Dijkstra's Algorithm

    - by DeadMG
    I've been tasked (coursework @ university) to implement a form of path-finding. Now, in-spec, I could just implement a brute force, since there's a limit on the number of nodes to search (begin, two in the middle, end), but I want to re-use this code and came to implement Dijkstra's algorithm. I've seen the pseudo on Wikipedia and a friend wrote some for me as well, but it flat out doesn't make sense. The algorithm seems pretty simple and it's not a problem for me to understand it, but I just can't for the life of me visualize the code that would realize such a thing. Any suggestions/tips?

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  • How to draw the "trail" in a maze solving application

    - by snow-spur
    Hello i have designed a maze and i want to draw a path between the cells as the 'person' moves from one cell to the next. So each time i move the cell a line is drawn Also i am using the graphics module The graphics module is an object oriented library Im importing from graphics import* from maze import* my circle which is my cell center = Point(15, 15) c = Circle(center, 12) c.setFill('blue') c.setOutline('yellow') c.draw(win) p1 = Point(c.getCenter().getX(), c.getCenter().getY()) this is my loop if mazez.blockedCount(cloc)> 2: mazez.addDecoration(cloc, "grey") mazez[cloc].deadend = True c.move(-25, 0) p2 = Point(getX(), getY()) line = graphics.Line(p1, p2) cloc.col = cloc.col - 1 Now it says getX not defined every time i press a key is this because of p2???

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  • Available message types in JMS?

    - by Caylem
    This is based on a past exam question. The question is asking to describe the four types of message available using JMS. The problem is it says the four, not just four. So it assumes their is only four, no more no less. However according to this site their seems to be five; streams maps text objects bytes *Another book states that XML is another potential type in future versions of JMS. Is XML already available? Am I missing something or is the question just wrong? Thanks.

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