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  • Need help with Django tutorial

    - by Nai
    I'm doing the Django tutorial here: http://docs.djangoproject.com/en/1.2/intro/tutorial03/ My TEMPLATE_DIRS in the settings.py looks like this: TEMPLATE_DIRS = ( "/webapp2/templates/" "/webapp2/templates/polls" # Put strings here, like "/home/html/django_templates" or "C:/www/django/templates". # Always use forward slashes, even on Windows. # Don't forget to use absolute paths, not relative paths. ) My urls.py looks like this: from django.conf.urls.defaults import * from django.contrib import admin admin.autodiscover() urlpatterns = patterns('', (r'^polls/$', 'polls.views.index'), (r'^polls/(?P<poll_id>\d+)/$', 'polls.views.detail'), (r'^polls/(?P<poll_id>\d+)/results/$', 'polls.views.results'), (r'^polls/(?P<poll_id>\d+)/vote/$', 'polls.views.vote'), (r'^admin/', include(admin.site.urls)), ) My views.py looks like this: from django.template import Context, loader from polls.models import Poll from django.http import HttpResponse def index(request): latest_poll_list = Poll.objects.all().order_by('-pub_date')[:5] t = loader.get_template('c:/webapp2/templates/polls/index.html') c = Context({ 'latest_poll_list': latest_poll_list, }) return HttpResponse(t.render(c)) I think I am getting the path of my template wrong because when I simplify the views.py code to something like this, I am able to load the page. from django.http import HttpResponse def index(request): return HttpResponse("Hello, world. You're at the poll index.") My index template file is located at C:/webapp2/templates/polls/index.html. What am I doing wrong?

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  • Force language change from custom account creation script through url

    - by jax
    I have made a custom 'Account Creation' script so that users can login from my phone application. What I want is to be able to change the responses from the server depending on their locale. So when I request a page I would add lang=en or lang=zh etc. This works http://mysite.com/phone/my_custom_account_creation.php?lang=en Response: <resource classification="error" code="Error (Code: 500)"> <message>Please enter your name:</message> </resource> This does not work: http://mysite.com/phone/my_custom_account_creation.php?lang=zh Response: <resource classification="error" code="Error (Code: 500)"> <message>Please enter your name:</message> </resource> If I go into Joomla at set the default language to chinese, it works. <resource classification="error" code="Error (Code: 500)"> <message>????????</message> </resource> but http://mysite.com/phone/my_custom_account_creation.php?lang=en does not work, instead it continues to show the chinese version. What might I be able to do here?

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  • Wicket: Where to add components? Constructor? Or onBeforeRender?

    - by gmallett
    I'm a Wicket newb. This may just be my ignorance of the Wicket lifecycle so please enlighten me! My understanding is that Wicket WebPage objects are instantiated once and then serialized. This has led to a point of confusion for me, see below. Currently I have a template class which I intend to subclass. I followed the example in the Wicket docs demonstrating how to override the template's behavior in the subclass: protected void onBeforeRender() { add(new Label("title", getTitle())); super.onBeforeRender(); } protected String getTitle() { return "template"; } Subclass: protected String getTitle() { return "Home"; } This works very well. What's not clear to me are the "best practices" for this. It seems like onBeforeRender() is called on every request for the page, no? This seems like there would be substantially more processing done on a page if everything is in onBeforeRender(). I could easily follow the example of the other Wicket examples and add some components in the constructor that I do not want to override, but then I've divided by component logic into two places, something I'm hesitant to do. If I add a component that I intend to be in all subclasses, should I add it to the constructor or onBeforeRender()?

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  • Copy object using pointer (templates)

    - by Azodious
    How the push_back of stl::vector is implemented so it can make copy of any datatype .. may be pointer, double pointer and so on ... I'm implementing a template class having a function push_back almost similar to vector. Within this method a copy of argument should be inserted in internal memory allocated memory. but the argument is a pointer. (an object pointer). Can you pls tell how to create copy from pointer. so that if i delete the pointer in caller still the copy exists in my template class? Code base is as follows: template<typename T> class Vector { public: void push_back(const T& val_in) { T* a = *(new T(val_in)); m_pData[SIZE++] = a; } } Caller: Vector<MyClass*> v(3); MyClass* a = new MyClass(); a->a = 0; a->b = .5; v.push_back(a); delete a; Thanks.

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  • Nested bind expressions

    - by user328543
    This is a followup question to my previous question. #include <functional> int foo(void) {return 2;} class bar { public: int operator() (void) {return 3;}; int something(int a) {return a;}; }; template <class C> auto func(C&& c) -> decltype(c()) { return c(); } template <class C> int doit(C&& c) { return c();} template <class C> void func_wrapper(C&& c) { func( std::bind(doit<C>, std::forward<C>(c)) ); } int main(int argc, char* argv[]) { // call with a function pointer func(foo); func_wrapper(foo); // error // call with a member function bar b; func(b); func_wrapper(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); func_wrapper(std::bind(&bar::something, b, 42)); // error // call with a lambda expression func( [](void)->int {return 42;} ); func_wrapper( [](void)->int {return 42;} ); return 0; } I'm getting a compile errors deep in the C++ headers: functional:1137: error: invalid initialization of reference of type ‘int (&)()’ from expression of type ‘int (*)()’ functional:1137: error: conversion from ‘int’ to non-scalar type ‘std::_Bind(bar, int)’ requested func_wrapper(foo) is supposed to execute func(doit(foo)). In the real code it packages the function for a thread to execute. func would the function executed by the other thread, doit sits in between to check for unhandled exceptions and to clean up. But the additional bind in func_wrapper messes things up...

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  • jQuery - making sure content is loaded before it's faded in?

    - by Kenny Bones
    Hi, Nick Craver really helped me out alot with this code in this thread http://stackoverflow.com/questions/2743443/jquery-can-someone-help-stitching-jquery-code-with-ajaxcomplete/2743791#2743791 And it is working. But I notice that there's a small delay after I've clicked a link and before the content is actually loaded. It's not very intense content that's loaded either so I think it's got something to do with the order which things happen in the script. The original code looks like this: $('.dynload').live('click', function(){ var toLoad = $(this).attr('href')+' #content'; $('#content').fadeOut('fast',loadContent); $('#ajaxloader').fadeIn('normal'); function loadContent() { $('#content').load(toLoad,'',showNewContent()) } function showNewContent() { $('#content').fadeIn('fast',hideLoader()); //Cufon.replace('h1, h2, h3, h4, .menuwrapper', { fontFamily: 'advent'}); } function hideLoader() { $('#ajaxloader').fadeOut('normal'); } return false; }); The new code looks like this: $(function() { $('.dynload').live('click', function(){ $('#ajaxloader').fadeIn('fast'); $('#ajaxloaderfridge').fadeIn('fast'); var href = this.href + ' #content'; $('#content').fadeOut('fast',function() { $(this).load(href,'', function(data) { createMenus(); $('#ajaxloader').fadeOut('fast'); $('#ajaxloaderfridge').fadeOut('fast'); $('#content').fadeIn('fast'); Cufon.replace('h1, h2, h3, h4, .menuwrapper', { fontFamily: 'advent'}); }); }); return false; }); }); $(createMenus); function createMenus() { $('#kontrollpanel .slidepanels').kwicks({ min : 42, spacing : 3, isVertical : true, sticky : true, event : 'click' }); } In the original code, #content is faded out, then the function "loadContent" is started. Which is basically what is happening in the new script as well isn't it? And when I was using the old code, the content just faded out and faded in really fast and smooth and with no small pause delay before the content arrived.

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  • What is common between environments within a shell terminal session?

    - by Matt1776
    I have a custom shell script that runs each time a user logs in or identity is assumed, its been placed in /etc/profile.d and performs some basic env variable operations. Recently I added some code so that if screen is running it will reattach it without needing me to type anything. There are some problems however. If I log-in as root, and su - to another user, the code runs a second time. Is there a variable I can set when the code runs the first time that will prevent a second run of the code? I thought to write something to the disk but then I dont want to prevent the code from running if I begin a new terminal session. Here is the code in question. It first attempts to reattach - if unsuccessful because its already attached (as it might be on an interruped session) it will 'take' the session back. screen -r if [ -z "$STY" ]; then exec screen -dR fi Ultimately this bug prevents me from substituting user to another user because as soon as I do so, it grabs the screen session and puts me right back where I started. Pretty frustrating

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  • jQuery Mobile: How to run a callback-function before $.mobile.changePage?

    - by Jugi84
    I'm setting up a mobile app with jQuery Mobile and PhoneGap. What I want to do is that when I click link with id "news_link" I want jQuery to fetch data from database and put it to jQm's collapsible set. In my solution, I've wanted to use $.mobile.changePage inside callback functions because I want to wait until the data has been fetched and put inside the container before the code changes page. Here's the code: $(function() { $('#news_link').click(function(){ loadNewsFromDB(function(){ $.mobile.changePage( $("#news"), { transition: "slideup"} ); }); }); loadNewsFromDB is PhoneGap's SQLite database function which would fetch the data with more callback functions from database. The contents would be put to desired container with .html-function function loadNewsFromDB(){ //some code here theDB.transaction(function(tx) { tx.executeSql(sqlStr, [], onLoadNewsSuccess, onLoadNewsError); },onTxError, onTxSuccess); function onLoadNewsSuccess(tx, results){ //some code here $("#newsSet").html(htmlCodeAndContentToPut); Html is jQm's basic ui-modules: <!-- some html code here --!> <div data-role="page" id="news"> <div data-role="content"> <div id="newsSet" data-role="collapsible-set" data-mini="true"> With debugging I know that the code work up until it works very well unti it arrives to $.mobile.changePage-function. Somehow it doesn't change the page. I've checked the function it works well in other occasions, but not inside callback-functions. I would be very grateful if someone would give me a hand am I not seeing something obviously wrong or is something more specific? What other workarounds there is for fetching the data from SQLite, waiting for data to be fetched, putting the data to container and then changing the pages?

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  • Storing C++ templated objects as same type

    - by JaredC
    I have a class that is a core component of a performance sensitive code path, so I am trying to optimize it as much as possible. The class used to be: class Widget { Widget(int n) : N(n) {} .... member functions that use the constant value N .... const int N; // just initialized, will never change } The arguments to the constructor are known at compile time, so I have changed this class to a template, so that N can be compiled into the functions: template<int N> class Widget { .... member functions that use N .... } I have another class with a method: Widget & GetWidget(int index); However, after templating Widget, each widget has a different type so I cannot define the function like this anymore. I considered different inheritance options, but I'm not sure that the performance gain from the template would outweigh the cost of inherited function invocations. SO, my question is this: I am pretty sure I want the best of both worlds (compile-time / run-time), and it may not be possible. But, is there a way to gain the performance of knowing N at compile time, but still being able to return Widgets as the same type? Thanks!

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  • Custom stream wrappers, what could they be useful for in web applications?

    - by michael
    I suppose the concept is language agnostic, but I don't know what it's called in other languages. In PHP they're Stream Wrappers. In short, a wrapper class that allows manipulation of a streamable resource (resource that can be read to/written to/seek into, such as a file, a db, an url). For example, in a template engine (a view), upon including a template file such as: include "view.wrapper://path/to/my/template/file.phtml"; my custom wrapper, declared elsewhere and associated with "view.wrapper", would first intercepts the file to replace such things as short tags (<?=) with a more verbose counterpart (<?php echo). This allows developers to use short tags in views, even if the server isn't set to allow it. It can also be applied to the preprocessing of views pseudo syntax such as {@myVar} (e.g. replacing it with $this->myVar). This is only one application of custom stream wrappers, but the feature seems powerful enough to make me think that there are others that could make life a lot simpler for developers. What have you built, or thought about building, custom stream wrappers for? where have you seen some interesting implementations? I'm particularly interested in their applications in web development.

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  • Problems Expanding an Array in C++

    - by dxq
    I'm writing a simulation for class, and part of it involves the reproduction of organisms. My organisms are kept in an array, and I need to increase the size of the array when they reproduce. Because I have multiple classes for multiple organisms, I used a template: template <class orgType> void expandarray(orgType* oldarray, int& numitems, int reproductioncount) { orgType *newarray = new orgType[numitems+reproductioncount]; for (int i=0; i<numitems; i++) { newarray[i] = oldarray[i]; } numitems += reproductioncount; delete[] oldarray; oldarray = newarray; newarray = NULL; } However, this template seems to be somehow corrupting my data. I can run the program fine without reproduction (commenting out the calls to expandarray), but calling this function causes my program to crash. The program does not crash DURING the expandarray function, but crashes on access violation later on. I've written functions to expand an array hundreds of times, and I have no idea what I screwed up this time. Is there something blatantly wrong in my function? Does it look right to you? EDIT: Thanks for everyone's help. I can't believe I missed something so obvious. In response to using std::vector: we haven't discussed it in class yet, and as silly as it seems, I need to write code using the methods we've been taught.

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  • How to implement the "System.out.println(ClassName::MethodName <then my message>)" of Eclipse in Netbeans?

    - by Sen
    I would like to know if there is the same feature as in eclipse to automatically generate and print the System.out.println(ClassName::MethodName <then my message>) functionality (which will print the class name and method name for debugging in the console) in Netbeans also. For example, in Eclipse Editor, Typing syst + Ctrl+ Space will auto generate a System.out.println(ClassName::MethodName ) type output in the console. Is such a method available in Netbeans? As of now, I have only two methods here in Netbeans: sout + Tab (System.out.println()) and soutv + Tab (System.out.println(prints the variable used just above the line)) automatically. Let me rephrase, instead of myMethod1, I want to get the enclosing method name. Eg. : public class X { public void myMethod1(int a) { System.out.println(X::myMethod1()); // This should be produced when I type the Code-Template abbreviation (example: syst) and press tab (or corresponding key). } } public class Y { public void myMethod2(int b) { System.out.println(Y::myMethod2()); // This should be produced when I type the Code-Template abbreviation (example: syst) and press tab (or corresponding key). } } Update: With the following code template: syst = System.out.println("${classVar editable="false" currClassName default="getClass()"}"); I am able to print the classname, but still no clue for the Method name.

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  • reading keyboard input without "consuming" it in x86 assembly

    - by Bob
    Ok so here the deal: I have an assignment regarding DOS and interrupts: I need to write a sort of key-logger function that can be called from C code. what it means is a c program would call an assembly function called startlog that would indicate to start logging the keys pressed until a function called endlog is called. the logging should work like this: write the ascii value of any key pressed without disturbing the C code between startlog and endlog, meaning that if the C code also needs to read the input (let's say by scanf, it would work ok). I managed to write the logger by changing the interrupt vector 9th entry (interrupt for keyboard press) to a function I wrote that writes the values to a file, and it works fine. however the C code does not get the input. Basically what i did is read the key pressed using int 21h, however after reading the ascii value it is "consumed" so I need a way to either simulate the key press again or read the value without "consuming" it so next time a key is read it reads the same key. (I described the code in english because it is long and clumsy assembly code)

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  • Utility App with Navigation Controller and Table View on FlipSide.

    - by wdt
    Hi All. I am relatively new to the whole MVC way of looking at things. I have an application that is based on the "Utility" Application template. Everything in the MainView and FlipsideView is working great but now I need to add a TableView and Navigation Controller to the flipside. Without the navigation bar being on the MainView. So only once the user has tapped the info light button will the nav bar display on the flipside with a table view. I have been able to impliment the Table View on the side and populate it with data from an array. I am now struggling to link in a navigation controller so that the tableview can become interactive. When I place the nav bar code into the app delegate it appears on the MainView and not the flipside view. Where do I place the navigation bar code so that it will display on the flipsideview. I cannt seem to get the code in the right place. Also I am not sure I have the right code, do I put the UINavigationController code in the FlipSideViewController.m ? I am not grasping the concept of the naivgation controller fully I think . . . Here is the code to bring up the FlipView - (IBAction)showInfo { TableViewController *controller = [[TableViewController alloc] initWithNibName:@"TableViewController" bundle:nil]; controller.delegate = self; controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:controller animated:YES]; [controller release]; } Now I need to get the TableViewController to have a navigation controller and a table view Thanks in advance.

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  • Difference between std::result_of and decltype

    - by Luc Touraille
    I have some trouble understanding the need for std::result_of in C++0x. If I understood correctly, result_of is used to obtain the resulting type of invoking a function object with certain types of parameters. For example: template <typename F, typename Arg> typename std::result_of<F(Arg)> invoke(F f, Arg a) { return f(a); } I don't really see the difference with the following code: template <typename F, typename Arg> auto invoke(F f, Arg a) -> decltype(f(a)) //uses the f parameter { return f(a); } or template <typename F, typename Arg> auto invoke(F f, Arg a) -> decltype(F()(a)); //"constructs" an F { return f(a); } The only problem I can see with these two solutions is that we need to either: have an instance of the functor to use it in the expression passed to decltype. know a defined constructor for the functor. Am I right in thinking that the only difference between decltype and result_of is that the first one needs an expression whereas the second does not?

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  • Hiding instantiated templates in shared library created with g++

    - by jchl
    I have a file that contains the following: #include <map> class A {}; void doSomething() { std::map<int, A> m; } When compiled into a shared library with g++, the library contains dynamic symbols for all the methods of std::map<int, A>. Since A is private to this file, there is no possibility that std::map will be instantiated in any other shared library with the same parameters, so I'd like to make the template instantiation hidden (for some of the reasons described in this document). I thought I should be able to do this by adding an explicit instantiation of the template class and marking it as hidden, like so: #include <map> class A {}; template class __attribute__((visibility ("hidden"))) std::map<int, A>; void doSomething() { std::map<int, A> m; } However, this has no effect: the symbols are still all exported. I even tried compiling with -fvisibility=hidden, but this also has no effect on the visibility of the methods of std::map<int, A> (although it does hide doSomething). The document I linked to above describes the use of export maps to restrict visibility, but that seems very tedious. Is there a way to do what I want in g++ (other than using export maps)? If so, what is it? If not, is there a good reason why these symbols must always be exported, or is this just a omission in g++?

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  • Is this an error in "More Effective C++" in Item28?

    - by particle128
    I encountered a question when I was reading the item28 in More Effective C++ .In this item, the author shows to us that we can use member template in SmartPtr such that the SmartPtr<Cassette> can be converted to SmartPtr<MusicProduct>. The following code is not the same as in the book,but has the same effect. #include <iostream> class Base{}; class Derived:public Base{}; template<typename T> class smart{ public: smart(T* ptr):ptr(ptr){} template<typename U> operator smart<U>() { return smart<U>(ptr); } ~smart(){delete ptr;} private: T* ptr; }; void test(const smart<Base>& ) {} int main() { smart<Derived> sd(new Derived); test(sd); return 0; } It indeed can be compiled without compilation error. But when I ran the executable file, I got a core dump. I think that's because the member function of the conversion operator makes a temporary smart, which has a pointer to the same ptr in sd (its type is smart<Derived>). So the delete directive operates twice. What's more, after calling test, we can never use sd any more, since ptr in sd has already been delete. Now my questions are : Is my thought right? Or my code is not the same as the original code in the book? If my thought is right, is there any method to do this? Thanks very much for your help.

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  • Flash Builder 4 "includeIn" property causing design view error

    - by Chris
    I am creating a custom TextInput component that will define an "error" state. I have extended the TextInput class to change the state to "error" if the errorString property's length is greater than 0. In the skin class, I have defined an "error" state, and added some logic to detect the size and position of the error icon. However, if I have this code at the same time I use the "includeIn" property in the bitmap image tag, I get a design view error. If I either A) Only include that code with no "includeIn" property set, it works or B) dont include the code to set the icon size and position and only use the "includeIn" property, it works. Any ideas what could be causing the design view problem when I use both the "includeIn" property and the icon size/position code at the same time? TextInput Class: package classes { import spark.components.TextInput; public class TextInput extends spark.components.TextInput { [SkinState("error")]; public function TextInput() { super(); } override public function set errorString( value:String ):void { super.errorString = value; invalidateSkinState(); } override protected function getCurrentSkinState():String { if (errorString.length>0) { return "error"; } return super.getCurrentSkinState(); } } } TextInput Skin File: override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void { //THIS IS THE CODE THAT SEEMS TO BE CAUSING THE PROBLEM if(getStyle("iconSize") == "large") { errorIcon.right = -12; errorIcon.source = new errorIconLg(); } else { errorIcon.right = -5; errorIcon.source = new errorIconSm(); } super.updateDisplayList(unscaledWidth, unscaledHeight); } </fx:Script> <s:states> <s:State name="normal"/> <s:State name="disabled"/> <s:State name="error"/> </s:states> //If I remove the problem code above or if I take out the includeIn //property here, it works <s:BitmapImage id="errorIcon" verticalCenter="0" includeIn="error" /> </s:SparkSkin>

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  • Turning logical expression around

    - by BluePrint
    I have the following code: bool s = true; for (...; ...; ...) { // code that defines A, B, C, D // and w, x, y, z if (!(A < w) && s == true) { s = false; } if (!(B < x) && s == true) { s = false; } if (!(C < y) && s == true) { s = false; } if (!(D < z) && s == true) { s = false; } } This code is working well. However, I want to, for several (unimportant) reasons, change the code so that I can initiate s = false; and set it to true inside the if-statement. It tried the following: bool s = false; for (...; ...; ...) { // code that defines A, B, C, D // and w, x, y, z if (A >= w && s == false) { s = true; } if (B >= x && s == false) { s = true; } if (C >= y && s == false) { s = true; } if (D >= z && s == false) { s = true; } } However, this is not working properly as the code above is working. I know thought wrong somewhere in the logic, but I can't figure out where. Does anbyone see my probably obvious error? EDIT: Added three more if-statemets. Missed them since they were commented away.

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  • Error in value of default parameter [Bug in Visual C++ 2008?]

    - by HellBoy
    I am facing following issue while trying to use template in my code I have some C++ code which i call from C functions. Problem is I am getting different values in the following code for statement 1 and 2. Type id : unsigned int statement 1 : 4 statement 2 : 1 C++ Code : template <typename T> void func(T* value, unsigned int len = sizeof(T)) { cout << "Type id : " << typeid(T).name() << endl; cout << "statement 1 " << sizeof(T) << endl; cout << "statement 2 " << len << endl; } template <typename T> void func1(T data) { T val = data; func(&val); } C Code : void test(void *ptr, unsigned int len) { switch(len) { case 1: func1(*(static_cast<uint32_t *>(ptr)) break; } } This happens only on windows. On Linux it works fine.

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  • Merging Three or More Images -- PHP

    - by bballer13sn
    Before I ask my question, I'd like to thank you all in advance for helping me with this. So here's the question: So, for my website, I've been trying to make it so people's characters (which are currently composed of several pictures that are moved by CSS) are merged into one image as to make my life easier. The chunk of code that currently doesn't work is as follows: $template = $charRow['template']; $gender = $charRow['gender']; $shirt = $charRow['shirt']; $pants = $charRow['pants']; $hat = $charRow['hat']; $templatePic = imagecreatefrompng("Templates/".$template); if (!empty($shirt)) { $shirtPic = imagecreatefrompng($shirt); imagecopy($templatePic,$shirtPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($pants)) { $pantsPic = imagecreatefrompng($pants); imagecopy($templatePic,$pantsPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($hat)) { $hatPic = imagecreatefrompng($hat); imagecopy($templatePic,$hatPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } imagePNG($templatePic, 'Images/'); //Problem line... This is the error PHP is giving me: Warning: imagepng() [function.imagepng]: Unable to open 'Images/' for writing: Is a directory in PathToParentFolderOfFollowingFile/testFile.php on line 139 What exactly does this error mean and how can it be fixed? NOTE: $charRow is not the problem. The query to get that is just not being displayed to all of you.

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  • C++0x Smart Pointer Comparisons: Inconsistent, what's the rationale?

    - by GManNickG
    In C++0x (n3126), smart pointers can be compared, both relationally and for equality. However, the way this is done seems inconsistent to me. For example, shared_ptr defines operator< be equivalent to: template <typename T, typename U> bool operator<(const shared_ptr<T>& a, const shared_ptr<T>& b) { return std::less<void*>()(a.get(), b.get()); } Using std::less provides total ordering with respect to pointer values, unlike a vanilla relational pointer comparison, which is unspecified. However, unique_ptr defines the same operator as: template <typename T1, typename D1, typename T2, typename D2> bool operator<(const unique_ptr<T1, D1>& a, const unique_ptr<T2, D2>& b) { return a.get() < b.get(); } It also defined the other relational operators in similar fashion. Why the change in method and "completeness"? That is, why does shared_ptr use std::less while unique_ptr uses the built-in operator<? And why doesn't shared_ptr also provide the other relational operators, like unique_ptr? I can understand the rationale behind either choice: with respect to method: it represents a pointer so just use the built-in pointer operators, versus it needs to be usable within an associative container so provide total ordering (like a vanilla pointer would get with the default std::less predicate template argument) with respect to completeness: it represents a pointer so provide all the same comparisons as a pointer, versus it is a class type and only needs to be less-than comparable to be used in an associative container, so only provide that requirement But I don't see why the choice changes depending on the smart pointer type. What am I missing? Bonus/related: std::shared_ptr seems to have followed from boost::shared_ptr, and the latter omits the other relational operators "by design" (and so std::shared_ptr does too). Why is this?

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  • Looking for something to add some standard rules for my c++ project.

    - by rkb
    Hello all, My team is developing a C++ project on linux. We use vim as editor. I want to enforce some code standard rules in our team in such a way that if the code is not in accordance with it, some sort of warning or error will be thrown when it builds or compiles. Not necessarily it builds but at least I can run some plugin or tools on that code to make sure it meets the standard. So that before committing to svn everyone need to run the code through some sort of plugin or script and make sure it meets the requirement and then only he/she can commit. Not sure if we can add some rules to vim, if there are any let me know about it. For eg. In our code standards all the member variables and private functions should start with _ class A{ private: int _count; float _amount; void _increment_count(){ ++_count; } } So I want to throw some warning or error or some sort of messages for this class if the variables are declared as follows. class A{ private: int count; float amount; void increment_count(){ ++_count; } } Please note that warning and error are not from compiler becoz program is still valid. Its from the tool I want to use so that code goes to re-factoring but still works fine on the executable side. I am looking for some sort of plugin or pre parsers or scripts which will help me in achieving all this. Currently we use svn; just to anser the comment.

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  • These are few objective type questions which i was not able to find the solution [closed]

    - by Tarun
    1. Which of the following advantages does System.Collections.IDictionaryEnumerator provide over System.Collections.IEnumerator? a. It adds properties for direct access to both the Key and the Value b. It is optimized to handle the structure of a Dictionary. c. It provides properties to determine if the Dictionary is enumerated in Key or Value order d. It provides reverse lookup methods to distinguish a Key from a specific Value 2. When Implementing System.EnterpriseServices.ServicedComponent derived classes, which of the following statements are true? a. Enabling object pooling requires an attribute on the class and the enabling of pooling in the COM+ catalog. b. Methods can be configured to automatically mark a transaction as complete by the use of attributes. c. You can configure authentication using the AuthenticationOption when the ActivationMode is set to Library. d. You can control the lifecycle policy of an individual instance using the SetLifetimeService method. 3. Which of the following are true regarding event declaration in the code below? class Sample { event MyEventHandlerType MyEvent; } a. MyEventHandlerType must be derived from System.EventHandler or System.EventHandler<TEventArgs> b. MyEventHandlerType must take two parameters, the first of the type Object, and the second of a class derived from System.EventArgs c. MyEventHandlerType may have a non-void return type d. If MyEventHandlerType is a generic type, event declaration must use a specialization of that type. e. MyEventHandlerType cannot be declared static 4. Which of the following statements apply to developing .NET code, using .NET utilities that are available with the SDK or Visual Studio? a. Developers can create assemblies directly from the MSIL Source Code. b. Developers can examine PE header information in an assembly. c. Developers can generate XML Schemas from class definitions contained within an assembly. d. Developers can strip all meta-data from managed assemblies. e. Developers can split an assembly into multiple assemblies. 5. Which of the following characteristics do classes in the System.Drawing namespace such as Brush,Font,Pen, and Icon share? a. They encapsulate native resource and must be properly Disposed to prevent potential exhausting of resources. b. They are all MarshalByRef derived classes, but functionality across AppDomains has specific limitations. c. You can inherit from these classes to provide enhanced or customized functionality 6. Which of the following are required to be true by objects which are going to be used as keys in a System.Collections.HashTable? a. They must handle case-sensitivity identically in both the GetHashCode() and Equals() methods. b. Key objects must be immutable for the duration they are used within a HashTable. c. Get HashCode() must be overridden to provide the same result, given the same parameters, regardless of reference equalityl unless the HashTable constructor is provided with an IEqualityComparer parameter. d. Each Element in a HashTable is stored as a Key/Value pair of the type System.Collections.DictionaryElement e. All of the above 7. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. A Nullable type is a structure. c. An implicit conversion exists from any non-nullable value type to a nullable form of that type. d. An implicit conversion exists from any nullable value type to a non-nullable form of that type. e. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 8. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 9. Which of the following does using Initializer Syntax with a collection as shown below require? CollectionClass numbers = new CollectionClass { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; a. The Collection Class must implement System.Collections.Generic.ICollection<T> b. The Collection Class must implement System.Collections.Generic.IList<T> c. Each of the Items in the Initializer List will be passed to the Add<T>(T item) method d. The items in the initializer will be treated as an IEnumerable<T> and passed to the collection constructor+K110 10. What impact will using implicitly typed local variables as in the following example have? var sample = "Hello World"; a. The actual type is determined at compilation time, and has no impact on the runtime b. The actual type is determined at runtime, and late binding takes effect c. The actual type is based on the native VARIANT concept, and no binding to a specific type takes place. d. "var" itself is a specific type defined by the framework, and no special binding takes place 11. Which of the following is not supported by remoting object types? a. well-known singleton b. well-known single call c. client activated d. context-agile 12. In which of the following ways do structs differ from classes? a. Structs can not implement interfaces b. Structs cannot inherit from a base struct c. Structs cannot have events interfaces d. Structs cannot have virtual methods 13. Which of the following is not an unboxing conversion? a. void Sample1(object o) { int i = (int)o; } b. void Sample1(ValueType vt) { int i = (int)vt; } c. enum E { Hello, World} void Sample1(System.Enum et) { E e = (E) et; } d. interface I { int Value { get; set; } } void Sample1(I vt) { int i = vt.Value; } e. class C { public int Value { get; set; } } void Sample1(C vt) { int i = vt.Value; } 14. Which of the following are characteristics of the System.Threading.Timer class? a. The method provided by the TimerCallback delegate will always be invoked on the thread which created the timer. b. The thread which creates the timer must have a message processing loop (i.e. be considered a UI thread) c. The class contains protection to prevent reentrancy to the method provided by the TimerCallback delegate d. You can receive notification of an instance being Disposed by calling an overload of the Dispose method. 15. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 16. Which of the following scenarios are applicable to Window Workflow Foundation? a. Document-centric workflows b. Human workflows c. User-interface page flows d. Builtin support for communications across multiple applications and/or platforms e. All of the above 17. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 18 While using the capabilities supplied by the System.Messaging classes, which of the following are true? a. Information must be explicitly converted to/from a byte stream before it uses the MessageQueue class b. Invoking the MessageQueue.Send member defaults to using the System.Messaging.XmlMessageFormatter to serialize the object. c. Objects must be XMLSerializable in order to be transferred over a MessageQueue instance. d. The first entry in a MessageQueue must be removed from the queue before the next entry can be accessed e. Entries removed from a MessageQueue within the scope of a transaction, will be pushed back into the front of the queue if the transaction fails. 19. Which of the following are true about declarative attributes? a. They must be inherited from the System.Attribute. b. Attributes are instantiated at the same time as instances of the class to which they are applied. c. Attribute classes may be restricted to be applied only to application element types. d. By default, a given attribute may be applied multiple times to the same application element. 20. When using version 3.5 of the framework in applications which emit a dynamic code, which of the following are true? a. A Partial trust code can not emit and execute a code b. A Partial trust application must have the SecurityCriticalAttribute attribute have called Assert ReflectionEmit permission c. The generated code no more permissions than the assembly which emitted it. d. It can be executed by calling System.Reflection.Emit.DynamicMethod( string name, Type returnType, Type[] parameterTypes ) without any special permissions Within Windows Workflow Foundation, Compensating Actions are used for: a. provide a means to rollback a failed transaction b. provide a means to undo a successfully committed transaction later c. provide a means to terminate an in process transaction d. achieve load balancing by adapting to the current activity 21. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 22. Which of the following controls allows the use of XSL to transform XML content into formatted content? a. System.Web.UI.WebControls.Xml b. System.Web.UI.WebControls.Xslt c. System.Web.UI.WebControls.Substitution d. System.Web.UI.WebControls.Transform 23. To which of the following do automatic properties refer? a. You declare (explicitly or implicitly) the accessibility of the property and get and set accessors, but do not provide any implementation or backing field b. You attribute a member field so that the compiler will generate get and set accessors c. The compiler creates properties for your class based on class level attributes d. They are properties which are automatically invoked as part of the object construction process 24. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. An implicit conversion exists from any non-nullable value type to a nullable form of that type. c. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 25. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is accessible via reflection. c. The compiler generates a code that will store the information separately from the instance to ensure its security. 26. When using an implicitly typed array, which of the following is most appropriate? a. All elements in the initializer list must be of the same type. b. All elements in the initializer list must be implicitly convertible to a known type which is the actual type of at least one member in the initializer list c. All elements in the initializer list must be implicitly convertible to common type which is a base type of the items actually in the list 27. Which of the following is false about anonymous types? a. They can be derived from any reference type. b. Two anonymous types with the same named parameters in the same order declared in different classes have the same type. c. All properties of an anonymous type are read/write. 28. Which of the following are true about Extension methods. a. They can be declared either static or instance members b. They must be declared in the same assembly (but may be in different source files) c. Extension methods can be used to override existing instance methods d. Extension methods with the same signature for the same class may be declared in multiple namespaces without causing compilation errors

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  • MIPS: removing non alpha-numeric characters from a string

    - by Kron
    I'm in the process of writing a program in MIPS that will determine whether or not a user entered string is a palindrome. It has three subroutines which are under construction. Here is the main block of code, subroutines to follow with relevant info: .data Buffer: .asciiz " " # 80 bytes in Buffer intro: .asciiz "Hello, please enter a string of up to 80 characters. I will then tell you if that string was a palindrome!" .text main: li $v0, 4 # print_string call number la $a0, intro # pointer to string in memory syscall li $v0, 8 #syscall code for reading string la $a0, Buffer #save read string into buffer li $a1, 80 #string is 80 bytes long syscall li $s0, 0 #i = 0 li $t0, 80 #max for i to reach la $a0, Buffer jal stripNonAlpha li $v0, 4 # print_string call number la $a0, Buffer # pointer to string in memory syscall li $s0, 0 jal findEnd jal toUpperCase li $v0, 4 # print_string call number la $a0, Buffer # pointer to string in memory syscall Firstly, it's supposed to remove all non alpha-numeric characters from the string before hand, but when it encounters a character designated for removal, all characters after that are removed. stripNonAlpha: beq $s0, $t0, stripEnd #if i = 80 end add $t4, $s0, $a0 #address of Buffer[i] in $t4 lb $s1, 0($t4) #load value of Buffer[i] addi $s0, $s0, 1 #i = i + 1 slti $t1, $s1, 48 #if ascii code is less than 48 bne $t1, $zero, strip #remove ascii character slti $t1, $s1, 58 #if ascii code is greater than 57 #and slti $t2, $s1, 65 #if ascii code is less than 65 slt $t3, $t1, $t2 bne $t3, $zero, strip #remove ascii character slti $t1, $s1, 91 #if ascii code is greater than 90 #and slti $t2, $s1, 97 #if ascii code is less than 97 slt $t3, $t1, $t2 bne $t3, $zero, strip #remove ascii character slti $t1, $s1, 123 #if ascii character is greater than 122 beq $t1, $zero, strip #remove ascii character j stripNonAlpha #go to stripNonAlpha strip: #add $t5, $s0, $a0 #address of Buffer[i] in $t5 sb $0, 0($t4) #Buffer[i] = 0 #addi $s0, $s0, 1 #i = i + 1 j stripNonAlpha #go to stripNonAlpha stripEnd: la $a0, Buffer #save modified string into buffer jr $ra #return Secondly, it is supposed to convert all lowercase characters to uppercase. toUpperCase: beq $s0, $s2, upperEnd add $t4, $s0, $a0 lb $s1, 0($t4) addi $s1, $s1, 1 slti $t1, $s1, 97 #beq $t1, $zero, upper slti $t2, $s1, 123 slt $t3, $t1, $t2 bne $t1, $zero, upper j toUpperCase upper: add $t5, $s0, $a0 addi $t6, $t6, -32 sb $t6, 0($t5) j toUpperCase upperEnd: la $a0, Buffer jr $ra The final subroutine, which checks if the string is a palindrome isn't anywhere near complete at the moment. I'm having trouble finding the end of the string because I'm not sure what PC-SPIM uses as the carriage return character. Any help is appreciated, I have the feeling most of my problems result from something silly and stupid so feel free to point out anything, no matter how small.

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