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  • How to use avg function?

    - by Marcelo
    I'm new at php and mysql stuff and i'm trying to use an avg function but i don't know how to. I'm trying to do something like this: mysql_connect(localhost,$username,$password); @mysql_select_db($database) or die ("Did not connect to $database"); mysql_query("AVG(column1) FROM table1 ") or die(mysql_error()); mysql_close(); echo AVG(column1); (Q1)I'd like to see the value printed in the screen, but i'm getting nothing but an error message. How could I print this average on the screen ? (Q2)If I had a column month in my table1, how could I print the averages by the months ? Sorry for any bad English, and thanks for the attention.

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  • How to handle array element between int and Integer

    - by masato-san
    First, it is long post so if you need clarification please let me know. I'm new to Java and having difficulty deciding whether I should use int[] or Integer[]. I wrote a function that find odd_number from int[] array. public int[] find_odd(int[] arr) { int[] result = new int[arr.length]; for(int i=0; i<arr.length; i++) { if(arr[i] % 2 != 0) { //System.out.println(arr[i]); result[i] = arr[i]; } } return result; } Then, when I pass the int[] array consisting of some integer like below: int[] myArray = {-1, 0, 1, 2, 3}; int[] result = find_odd(myArray); The array "result" contains: 0, -1, 0, 1, 0, 3 Because in Java you have to define the size of array first, and empty int[] array element is 0 not null. So when I want to test the find_odd() function and expect the array to have odd numbers (which it does) only, it throws the error because the array also includes 0s representing "empty cell" as shown above. My test code: public void testFindOddPassValidIntArray() { int[] arr = {-2, -1, 0, 1, 3}; int[] result = findOddObj.find_odd(arr); //check if return array only contain odd number for(int i=0; i<result.length; i++) { if(result[i] != null) { assert is_odd(result[i]) : result[i]; } } } So, my question is should I use int[] array and add check for 0 element in my test like: if(result[i] != 0) { assert is_odd(result[i] : result[i] } But in this case, if find_odd() function is broken and returning 0 by miscalculation, I can't catch it because my test code would only assume that 0 is empty cell. OR should I use Integer[] array whose default is null? How do people deal with this kind of situation?

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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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  • returning reference to a vector from a method and using its public members

    - by memC
    dear experts, I have a vector t_vec that stores references to instances of class Too. The code is shown below. In the main , I have a vector t_vec_2 which has the same memory address as B::t_vec. But when I try to access t_vec_2[0].val1 it gives error val1 not declared. Could you please point out what is wrong? Also, if you know of a better way to return a vector from a method, please let me know! Thanks in advance. class Too { public: Too(); ~Too(){}; int val1; }; Too::Too(){ val1 = 10; }; class B { public: vector<Too*> t_vec; Too* t1; vector<Too*>& get_tvec(); B(){t1 = new Too();}; ~B(){delete t1;}; }; vector<Too*>& B::get_tvec(){ t_vec.push_back(t1); return t_vec; } int main(){ B b; b = B(); vector<Too*>& t_vec_2 = b.get_tvec(); // Getting error std::cout << "\n val1 = " << t_vec_2[0].val1; return 0; }

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  • How to get global access to enum types in C#?

    - by lala
    This is probably a stupid question, but I can't seem to do it. I want to set up some enums in one class like this: public enum Direction { north, east, south, west }; Then have that enum type accessible to all classes so that some other class could for instance have: Direction dir = north; and be able to pass the enum type between classes: public void changeDirection(Direction direction) { dir = direction; } I thought that setting the enum to public would make this automatically possible, but it doesn't seem to be visible outside of the class I declared the enum in.

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  • WPF DataContext syntax - Convert from C# to VB

    - by hawbsl
    Currently working through a Teach Yourself WPF tutorial. Usually I can mentally convert from C# to VB without any problem but this C# syntax is unfamiliar. How is it written in VB? Private void Button_Click(object sender, RoutedEventArgs e) { ((Person)DataContext).FirstName = "blah blah" } My usual fave online converters are choking on this ... perhaps because they don't do WPF?

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • do the Python libraries have a natural dependence on the global namespace?

    - by msw
    I first ran into this when trying to determine the relative performance of two generators: t = timeit.repeat('g.get()', setup='g = my_generator()') So I dug into the timeit module and found that the setup and statement are evaluated with their own private, initially empty namespaces so naturally the binding of g never becomes accessible to the g.get() statement. The obvious solution is to wrap them into a class, thus adding to the global namespace. I bumped into this again when attempting, in another project, to use the multiprocessing module to divide a task among workers. I even bundled everything nicely into a class but unfortunately the call pool.apply_async(runmc, arg) fails with a PicklingError because buried inside the work object that runmc instantiates is (effectively) an assignment: self.predicate = lambda x, y: x > y so the whole object can't be (understandably) pickled and whereas: def foo(x, y): return x > y pickle.dumps(foo) is fine, the sequence bar = lambda x, y: x > y yields True from callable(bar) and from type(bar), but it Can't pickle <function <lambda> at 0xb759b764>: it's not found as __main__.<lambda>. I've given only code fragments because I can easily fix these cases by merely pulling them out into module or object level defs. The bug here appears to be in my understanding of the semantics of namespace use in general. If the nature of the language requires that I create more def statements I'll happily do so; I fear that I'm missing an essential concept though. Why is there such a strong reliance on the global namespace? Or, what am I failing to understand? Namespaces are one honking great idea -- let's do more of those!

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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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  • 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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  • 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). Note: I cannot rely on IDs to determine the uniqueness. i.e. I might end up forming something like: <li id="elemli3">Element 1</li> Do I go about using hashmaps?

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