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  • C# Using singleton instead of a global static instance

    - by Farstucker
    I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? Thanks for your help.

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  • 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.

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  • How can I define a verb in J that applies a different verb alternately to each atom in a list?

    - by Gregory Higley
    Imagine I've defined the following name in J: m =: >: i. 2 4 5 This looks like the following: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 I want to create a monadic verb of rank 1 that applies to each list in this list of lists. It will double (+:) or add 1 (>:) to each alternate item in the list. If we were to apply this verb to the first row, we'd get 2 3 6 5 10. It's fairly easy to get a list of booleans which alternate with each item, e.g., 0 1 $~{:$ m gives us 0 1 0 1 0. I thought, aha! I'll use something like +:`>: @. followed by some expression, but I could never quite get it to work. Any suggestions? UPDATE The following appears to work, but perhaps it can be refactored into something more elegant by a J pro. poop =: monad define (($ y) $ 0 1 $~{:$ y) ((]+:)`(]:) @. [)"0 y )

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  • 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 :)

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  • 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..

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  • 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?

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  • How to turn off startup text of GNU gdb in XCode

    - by willc2
    I'm new to XCode 3.1.2 and Objective-C 2.0. I've just discovered using breakpoints for logging instead of littering the code with millions of NSLog() statements. The problem is, when the debugger starts up it spews half a screen full of status and credits info into the console. Is there any way to suppress this text?

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  • Global variables in Python

    - by rejinacm
    A global variable created in one function cannot be used in another function directly. Instead I need to store the global variable in a local variable of the function which needs its access. Am I correct? Why is it so?

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  • The conceptual process of populating related tables in a database (MySql) from a CSV file

    - by user322772
    I'm new to relational databases and all the material I've read covered primary and foreign keys, normal forms, and joins but left out to populate the database once it's created. How do you import a CSV file so the fields match their related table? Say you were tying to build a beer database and had a CSV file with each line as a record. Header: brewer, beer_name, country, city, state, beer_category, beer_type, alcohol_content Record 1: Anheuser-Busch, Budweiser, United States, St. Louis, Mo, Pale lager, Regular, 5.0% Record 2: Anheuser-Busch, Bud Light, United States, St. Louis, Mo, Pale lager Light, 4.2% Record 3: Miller Brewing Company, Miller Lite, United States, Milwaukee, WI, Pale lager, Light, 4.2% You can create a "Brewer" table and a "Beer" table. When importing how does you connect the primary keys between the tables?

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  • Applications of Unification?

    - by Ravi
    What are (practical) applications of Unification ? Where it is been used in real world? I couldn't get the whole idea of what it is really about and why its considered as a part of Artificial Intelligence.

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  • error with string list in C#

    - by Chelsea_cole
    Same namespace: 2 forms. public class Account //frm1 { public string Username; public string Password; } public class ListAcc { public static List<Account> UserList; } private void button1_Click(object sender, EventArgs e) { List<Account> UserList = new List<Account>(); Account acc = new Account(); acc.Username = textBox1.Text; acc.Password = textBox2.Text; UserList.Add(acc); } private void button2_Click(object sender, EventArgs e) //frm2 { string p = frmDangky.ListAcc.UserList[0].Username; // null ->error string p = frmDangky.ListAcc.UserList[0].Password; // null ->error } Someone help me? :( why my string is NULL???????? The textBox is not empty... Thanks!

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  • Interesting C projects that upgraded your skill level.

    - by JDQ
    I've been (thus far) unable to write a project in C that would be meaningful on any level. For a first project, I've thought of many, but done none. What was the project that changed your skill-level from noob to "coder" the most? Maybe I can take some tips and work on something similar? I was thinking of a toy language, but well, I wouldn't know how to go about that. This might be closed, but oh well :)

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  • 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!"; } }

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  • Why do I get "mysql_query(): supplied argument is not a valid"

    - by Brian Ojeda
    Why do I get a "mysql_query(): supplied argument is not a valid" for the first... $r = mysql_query($q, $connection); In the following code... $bId = trim($_POST['bId']); $title = trim($_POST['title']); $story = trim($_POST['story']); $q = "SELECT * "; $q .= "FROM " . DB_NAME . ".`blog` "; $q .= "WHERE `blog`.`id` = {$bId}"; $r = mysql_query($q, $connection); //confirm_query($r); if (mysql_num_rows($r) == 1) { $q = "UPDATE " . DB_NAME . ".`blog` SET `title` = '{$title}', `story` = '{$story}' WHERE `id` = {$bId}"; $r = mysql_query($q, $connection); if (mysql_affected_rows() == 1) { //Successful $data['success'] = true; $date['errors'] = false; $date['message'] = "You are the Greatest!"; } else { //Fail $data['success'] = false; $data['error'] = true; $date['message'] = "You can't do it fool!"; } } I also get an "mysql_num_rows(): supplied argument is not a valid MySQL result resource" error too. Side notes: I am using 1&1 Hosting (worst hosting ever), custom .htaccess file with one line text to enable PHP 5.2 (only why with 1&1 Hosting).

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  • 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

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  • How do I keep from running out of memory on graphics for an Android app?

    - by user279112
    I've been working on an Android app in Eclipse, and so far, my program hasn't really grown past midget size. However I've already run into an issue with an Out of Memory error. You see, I've been using graphics comprised solely of bitmaps and PNGs in this program, and recently, when I tried to add a little bit more functionality to the program (mainly including a few more bitmaps and causing an extra sprite to be created), it started crashing in the graphics thread's constructor - sprite's constructor. When I tracked the problem down, it turned out to be an Out of Memory error that is seemingly caused by adding too many picture files to the program and creating Drawables out of them. This would be a problem, as I really don't have that many picture resources worked into that program...maybe 20 or so. I haven't even started to include sound yet. These images aren't all that fancy. My questions are this: 1) Are programs for the Android phone really that limited on how much memory they can employ, or is it probably something other than the 20-30 resource pictures causing that error? 2) If the memory for Android apps is so awful it can't even handle 20-30 picture resources being loaded into Drawables that exist at the same time, then how in the world are you supposed to make decent graphics and sound for that thing? Thanks.

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  • What benefits can Java developer have from moving to a *NIX platform?

    - by dave-keiture
    Hi everyone, A friend of mine is a Java developer, who's using *NIX for ages. He claims that *NIX is for real Java geeks, whereas WIN is for dummies (and I'm one of them, according to him) and girls. When I ask him to argue his position, and explain, what's so good for Java developer on *NIX, he starts talking about console, wget, curl and grep. But sorry, wget and curl analogues exist for the WIN platform as well. As for the console - I'm using FAR Commander, and have access to the command line when I need. Moreover, even if I decide moving to *NIX, I will certainly use Netbeans or Eclipse on it, so there will be no big difference. Guys, who use Java on *NIX, could you please give me some real killer examples, when *NIX (any util or technique) dramatically increases Java development productivity (in the way the hints are given in "The Pragmatic Programmer"), or, which is also important, gives more fun from the process. Thanks in advance!

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  • 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?

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  • How Would a Newborn Baby Learn Web Programming?

    - by Mugatu
    Hello all, I chose that title because I equate my knowledge of web programming and web development with that of a newborn. Here's the shortest version of my story and what I'm looking to do: A friend and I have been coming up with website ideas for a couple years, mostly just jotting them down whenever we come up with a good, useful idea when browsing the web. For the past 6 months we've hired a couple different programmers to make a couple of the sites for us, but have been disappointed with how it's gone. Been too slow and too many miscommunications for our liking. So like the saying goes if you want something done right do it yourself, we're going to do it ourselves. I know nothing about programming, I've never written a line of code in my life. I consider myself very good with math and about as logical as you can get, but I have zero real-life programming knowledge. The sites we want to make are all pretty 'Web 2.0'ish', meaning user-generated content, commenting on posts, pages that change on the fly, etc. So here are some of my questions for anyone who's been there before: Is there a language you'd recommend learning first? Something that is a good indicator how most other languages work? What web programming languages do you recommend learning first based on popularity both now and the future. I don't want to learn a language that's going to be outdated by the time I'm an expert at it. Any specific books you'd recommend? Any general advice you'd give to someone literally starting at square zero for coding who plans on being in it for the long haul? Thanks in advance for the help

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  • creation of folders in python

    - by beena shamsudeen
    i want to create folders with the name of a pdf file for eg,abc.if it does not exists,i should create a folder with name abc_1...if abc_1 exists,i shud create abc_2.if both exxists,abc_3 and so on...the scripting is in python..can u help me??

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  • split twice in the same expression?

    - by UcanDoIt
    Imagine I have the following: inFile = "/adda/adas/sdas/hello.txt" # that instruction give me hello.txt Name = inFile.name.split("/") [-1] # that one give me the name I want - just hello Name1 = Name.split(".") [0] Is there any chance to simplify that doing the same job in just one expression?

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