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  • How should I return different types in a method based on the value of a string in Java?

    - by Siracuse
    I'm new to Java and I have come to having the following problem: I have created several classes which all implement the interface "Parser". I have a JavaParser, PythonParser, CParser and finally a TextParser. I'm trying to write a method so it will take either a File or a String (representing a filename) and return the appropriate parser given the extension of the file. Here is some psuedo-code of what I'm basically attempting to do: public Parser getParser(String filename) { String extension = filename.substring(filename.lastIndexOf(".")); switch(extension) { case "py": return new PythonParser(); case "java": return new JavaParser(); case "c": return new CParser(); default: return new TextParser(); } } In general, is this the right way to handle this situation? Also, how should I handle the fact that Java doesn't allow switching on strings? Should I use the .hashcode() value of the strings? I feel like there is some design pattern or something for handling this but it eludes me. Is this how you would do it?

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  • What are "named tuples" in Python?

    - by Denilson Sá
    Reading the changes in Python 3.1, I found something... unexpected: The sys.version_info tuple is now a named tuple: I never heard about named tuples before, and I thought elements could either be indexed by numbers (like in tuples and lists) or by keys (like in dicts). I never expected they could be indexed both ways. Thus, my questions are: What are named tuples? How to use them? Why/when should I use named tuples instead of normal tuples? Why/when should I use normal tuples instead of named tuples? Is there any kind of "named list" (a mutable version of the named tuple)?

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  • How to use Scanner to accept only valid int as input

    - by John
    I'm trying to make a small program more robust and I need some help with that. Scanner kb = new Scanner(System.in); int num1; int num2 = 0; System.out.print("Enter number 1: "); num1 = kb.nextInt(); while(num2<num1) { System.out.print("Enter number 2: "); num2 = kb.nextInt(); } Number 2 has to be greater than number 1 Also I want the program to automatically check and ignore if the user enters a character instead of a number. Because right now when a user enters for example r instead of a number the program just exits.

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  • How do I splice a python string programmatically?

    - by Robin Welch
    Very simple question, hopefully. So, in Python you can split up strings using indices as follows: >>> a="abcdefg" >>> print a[2:4] cd but how do you do this if the indices are based on variables? E.g. >>> j=2 >>> h=4 >>> print a[j,h] Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: string indices must be integers

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  • Same project...multiple apps?

    - by greypoint
    We have a an iPhone app project that we wish to deploy multiple times under different client names. The individual apps will be very similar but will have different resources (icon, images etc) and config settings stored in plists (server names, options etc). What is the preferred means to manage this in Xcode? Obviously we really don't want different XCode projects for each App deployment since it's 90% shared code.

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  • Python integer incrementing with ++

    - by Znarkus
    I've always laughed to myself when I looked back at my VB6 days, "What modern language doesn't allow incrementing with double plus signs?": number++ To my surprise I can't find anything about this in the Python docs. Must I really subject myself to number = number + 1? Doesn't people use the ++/-- notation? :-(

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  • What are good resources for computer graphics basics?

    - by Hanno Fietz
    During Flex programming, I recently ran into several questions (about box models, ways to join lines and misaligning pixels [on doctype]) regarding computer graphics and layout, where I felt that I lacked some basic background on things like concepts like the box model approaches mapping real numbers to a pixel raster (like font anti-aliasing) conventions found across drawing engines, like do you count y coordinates from top or bottom, and why I feel that reading some basic Wikipedia articles, books or tutorials on these subjects might help in phrasing my questions more specifically and debugging my code more systematically. I have repeatedly found myself writing tiny test apps in Flex, just to find out how the APIs do very basic stuff. My assumption would be that if I knew the right vocabulary and some general concepts, I could solve these questions much faster.

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  • number of elements in a static array of a predefined size

    - by cppb
    I have an array like this: int a[100]; I am filling only the first 4 elements in this array: a[0] = 1; a[1] = 2; a[2] = 3; a[3] = 4; When I do sizeof(a)/sizeof(a[0]) it returns 100. Is there a way I can get number of elements to which I have assinged a value and thus filtering out the remaining 96 unassigned elements? thanks

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  • Assigning a value to a variable gets stored in the wrong spot?

    - by scribbloid
    Hello, I'm relatively new to C, and this is baffling me right now. It's part of a much larger program, but I've written this little program to depict the problem I'm having. #include <stdio.h> int main() { signed int tcodes[3][1]; tcodes[0][0] = 0; tcodes[0][1] = 1000; tcodes[1][0] = 1000; tcodes[1][1] = 0; tcodes[2][0] = 0; tcodes[2][1] = 1000; tcodes[3][0] = 1000; tcodes[3][1] = 0; int x, y, c; for(c = 0; c <= 3; c++) { printf("%d %d %d\r\n", c, tcodes[c][0], tcodes[c][1]); x = 20; y = 30; } } I'd expect this program to output: 0 0 1000 1 1000 0 2 0 1000 3 1000 0 But instead, I get: 0 0 1000 1 1000 0 2 0 20 3 20 30 It does this for any number assigned to x and y. For some reason x and y are overriding parts of the array in memory. Can someone explain what's going on? Thanks!

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  • Is an ArrayList automatically declared static in Java, if it is an instance variable?

    - by Alex
    I'm trying to do something like this: private class aClass { private ArrayList<String> idProd; aClass(ArrayList<String> prd) { this.idProd=new ArrayList<String>(prd); } public ArrayList<String> getIdProd() { return this.idProd; } } So if I have multiple instances of ArrayLIst<String> (st1 ,st2 ,st3) and I want to make new objects of aClass: { aClass obj1,obj2,obj3; obj1=new aClass(st1); obj2=new aClass(st2); obj3=new aClass(st3); } Will all of the aClass objects return st3 if I access the method getIdProd() for each of them(obj1..obj3)? Is an ArrayList as an instance variable automatically declared static?

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  • What is the best script language for n/w programming + web development

    - by Mohanavel
    Hi, I'm interested in developing web application and networking application. For that what is the best script language to learn. Which one is effective for this two. So for, i don't know even a single syntax of any scripting language. Which is the best script for understanding, maintainable, effective and simple (may not). Please don't say what are all you know. Please tell me the best

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  • want to start programming

    - by Dan
    I really want to learn how to program. A friend suggested I buy vs 2005 or a newer version if I'm serious about it. Is there a cheaper route? I would like to start with c#.

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  • jQuery: Adding li element only if it not already there?

    - by Legend
    I am constructing an <li> element like this: var element = $("<li></li>") .html(mHTML) .attr('id', "elemid"); I am trying to add this element to a <ul> element only if it doesn't already exist. Any ideas on how to do this? Am I supposed to use contains() to see if the ul element contain the html and then decide? For instance, <ul id="elemul"> <li id="elemli1">Element 1</li> <li id="elemli2">Element 2</li> <li id="elemli3">Element 3</li> </ul> If I try adding Element 1, it should not add it. What should I do if its a longer string (not really long but about 150 characters). Do I go about using hashmaps?

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  • PHP Using session variables in array(s)

    - by Chris
    Hello, My question is how do i put these session variables into a array? I have tried countless ways but none of them work. Not really sure what to put in a array and what no and how to adress them. Currently when i fill in the form the data gets displayed in a table. Next when i press the hyperlink that takes me back to the same form, i wish to enter data again. This data should be added in a new row in the same display table. Best Regards. The code below (pardon me that it is not english). <?php session_start(); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-Strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>ExpoFormulier</title> <body> <?php if (!empty($_POST)) { $standnaam = $_POST["standnaam"]; $oppervlakte = $_POST["oppervlakte"]; //value in the form van checkboxes op 1 zetten! $verdieping = isset($_POST["verdieping"]) ? $_POST["verdieping"] : 0; $telefoon = isset($_POST["telefoon"]) ? $_POST["telefoon"] : 0; $netwerk = isset($_POST["netwerk"]) ? $_POST["netwerk"] : 0; if (is_numeric($oppervlakte)) { $_SESSION["standnaam"]=$standnaam; $_SESSION["oppervlakte"]=$oppervlakte; $_SESSION["verdieping"]=$verdieping; $_SESSION["telefoon"]=$telefoon; $_SESSION["netwerk"]=$netwerk; header("Location:ExpoOverzicht.php"); } else { echo "<h1>Foute gegevens, Opnieuw invullen a.u.b</h1>"; } } ?> <form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="post" id="form1"> <h1>Vul de gegevens in</h1> <table> <tr> <td>Standnaam:</td> <td><input type="text" name="standnaam" size="18"/></td> </tr> <tr> <td>Oppervlakte (in m^2):</td> <td><input type="text" name="oppervlakte" size="6"/></td> </tr> <tr> <td>Verdieping:</td> <td><input type="checkbox" name="verdieping" value="1"/></td> </tr> <tr> <td>Telefoon:</td> <td><input type="checkbox" name="telefoon" value="1"/></td> </tr> <tr> <td>Netwerk:</td> <td><input type="checkbox" name="netwerk" value="1"/></td> </tr> <tr> <td><input type="submit" name="verzenden" value="Verzenden"/></td> </tr> </table> </form> Second File: <?php session_start(); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-Strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>ExpoOverzicht</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link href="StyleSheetExpo.css" rel="stylesheet" type="text/css" /> </head> <body> <h1>Overzicht van de ingegeven standen in deze sessie</h1> <?php $standnaam = $_SESSION["standnaam"]; $oppervlakte = $_SESSION["oppervlakte"]; $verdieping = $_SESSION["verdieping"]; $telefoon = $_SESSION["telefoon"]; $netwerk = $_SESSION["netwerk"]; $result1 = 0; $result2 = 0; $result3 = 0; $prijsCom = 0; $prijsVerdieping = 0; for ($i=1; $i <= $oppervlakte; $i++) { if($i <= 10) { $tarief1 = 1 * 100; $result1 += $tarief1; } if($i > 10 && $i <= 30) { $tarief2 = 1 * 90; $result2 += $tarief2; } if($i > 30) { $tarief3 = 1 * 80; $result3 += $tarief3; } } $prijsOpp = $result1 + $result2 + $result3; if($verdieping == 1) { $prijsVerdieping = $oppervlakte * 120; } if(($telefoon == 1) || ($netwerk == 1)) { $prijsCom = 20; } if(($telefoon == 1) && ($netwerk == 1)) { $prijsCom = 30; } $totalePrijs = $prijsOpp + $prijsVerdieping + $prijsCom; echo "<table class=\"tableExpo\">"; echo "<th>Standnaam</th>"; echo "<th>Oppervlakte</th>"; echo "<th>Verdieping</th>"; echo "<th>Telefoon</th>"; echo "<th>Netwerk</th>"; echo "<th>Totale prijs</th>"; echo "<tr>"; echo "<td>".$standnaam."</td>"; echo "<td>".$oppervlakte."</td>"; echo "<td>".$verdieping."</td>"; echo "<td>".$telefoon."</td>"; echo "<td>".$netwerk."</td>"; echo "<td>".$totalePrijs."</td>"; echo "</tr>"; echo "</table>"; ?> <a href="ExpoFormulier.php">Terug naar het formulier</a> </body> </html> </body> </html>

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  • Help C++ifying this C style code.

    - by Flamewires
    Hey I'm used to developing in C and I would like to use C++ in a project. Can anyone give me an example of how I would translate this C-style code into C++ code. I know it should compile in a c++ complier but I'm talking using c++ techniques(I.e. classes, RAII) typedef struct Solution Solution; struct Solution { double x[30]; int itt_found; double value; }; Solution *NewSolution() { Solution *S = (Solution *)malloc(sizeof(Solution)); for (int i=0;<=30;i++) { S-x[i] = 0; } S-itt_found = -1; return S; } void FreeSolution(Solution *S) { if (S != NULL) free(S); } int main() { Solution *S = NewSolution(); S-value = eval(S-x);// evals is another function that returns a double S-itt_found = 0; FreeSolution(S); return EXIT_SUCCESS; } Ideally I would like to be able to so something like this in main, but I'm not sure exactly how to create the class, i've read a lot of stuff but incorporating it all together correctly seems a little hard atm. Solution S(30);//constructor that takes as an argument the size of the double array S.eval();//a method that would run eval on S.x[] and store result in S.value cout << S.value << endl; Ask if you need more info, thanks.

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  • How can I know whether my C++ string variable is a number or not

    - by user342580
    I have a string of class string string str; how can I check if it is a number or not, str can only have 3 possible types described below like abcd or a number like 123.4 or a number with a parenthesis attach to the end it for example 456) note the parenthesis at the end of "str" is the only possible combination of number and none number where the bottom two are considered valid numbers, I know I could use lexical_cast if only the first 2 cases occur, but how about considering all 3 possible cases to occur? I don't need to do anything fancy with str, I just need to know whether it is a valid number as I described

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  • Regular Expression Sanitize (PHP)

    - by atif089
    Hello, I would like to sanitize a string in to a URL so this is what I basically need. Everything must be removed except alphanumeric characters and spaces and dashed. Spaces should be converter into dashes. Eg. This, is the URL! must return this-is-the-url Thanks

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  • Strange Access Denied warning when running the simplest C++ program.

    - by DaveJohnston
    I am just starting to learn C++ (coming from a Java background) and I have come across something that I can't explain. I am working through the C++ Primer book and doing the exercises. Every time I get to a new exercise I create a new .cpp file and set it up with the main method (and any includes I think I will need) e.g.: #include <list> #include <vector> int main(int argc, char **args) { } and just to make sure I go to the command prompt and compile and run: g++ whatever.cpp a.exe Normally this works just fine and I start working on the exercise, but I just did it and got a strange error. It compiles fine, but when I run it it says Access Denied and AVG pops up telling me that a threat has been detected 'Trojan Horse Generic 17.CKZT'. I tried compiling again using the Microsoft Compiler (cl.exe) and it runs fines. So I went back, and added: #include <iostream> compiled using g++ and ran. This time it worked fine. So can anyone tell me why AVG would report an empty main method as a trojan horse but if the iostream header is included it doesn't?

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  • Filter some words

    - by bob
    I want to filter some reserved word on my title form. $adtitle = sanitize($_POST['title']); $ignore = array('sale','buy','rent'); if(in_array($adtitle, $ignore)) { $_SESSION['ignore_error'] = '<strong>'.$adtitle.'</strong> cannot be use as your title'; header('Location:/submit/'); exit; How to make something like this. If user type Car for sale the sale will detected as reserved keyword. Now my current code only detect single keyword only.

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  • Which MS technologies would be suited for a data intensive application?

    - by steve.tse
    I'm a junior VB.net developer with little application design knowledge. I've been reading a lot of material online regarding different design patterns, frameworks, and methodologies. It's become a bit confusing for me. Right now I'm trying to decide on what language would be best suited to convert an existing VB6 application (with SQL server backend.) I need to update the UI and add more user functionality and reporting capabilities. Initially I was thinking of using WPF and attempting the MVVM model for this big project. Reports would be generated from SSRS. A peer suggested using ASP.net and I don't have enough experience to determine what would be better. The senior programmers here are stuck on using VB6 and don't have any input on what to use. They are encouraging me to use the latest technologies. This application would be for ~20 users in a central location. Ideally I would stick to a Microsoft .net language. Current interface is similar to a datagrid table where the user would click in to see the detail of each record. They would need to have multiple records open at any given time. I look forward to all the advice I can get. EDIT 2010/04/22 2:47 PM EST What is your audience? Internal clients within an intranet How complex are the interactions you expect to implement? not very... displaying data from SQL server to UI. Allow user updates to said data. Typically just one user modifying a record. Do you require near real-time data updates? no How often do you expect to update the application after the first release? twice/year Do you expect a well-defined set of client platforms? Yes, windows xp environment, potentially upgrading to Win7. Currently in IE.6 moving to IE7 or 8 within a couple of months. Do users need access from anywhere? No, just from their PC.

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