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• How do I add restrictions for users to sign up before they can access web site?

  - by user1867842

  How do I get my webpage not to go back when they hit the back button and are logged out and how can I add a web page to be blocked like FACEBOOK doesn't let you get into their site with out having a page or a account with them, and if you try to put something in the url and try to go to something on their site it gives you a web page that says "you have to be logged in first" . Like I don't want someone going to the url of the "index" page before they have signed up as a member they need to make an account first then they can have access to the "index" page. How do I do this. I have a website so far that has a database and the website has 5 pages so far and two of them which is the login and sign up page which are both used with php and mysql and they work fine. How do I restrict access to the main website by first having the users sign up with me for an account.

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• Bridging the gap between learning language fundamentals and actually making useful software?

  - by Anonymous -

  I'm learning C# via the "Essential C#" Lynda.com video tutorials and plan to read a couple of books that cover things in more depth afterwards. My question is where I should head to learn more after that? I've done things like project Euler in the past, but I find they don't really help me learn anything other than basic program control flow and features. I've looked at many open-source projects but pretty much everything still looks overwhelmingly complicated at this stage. What would you recommend I look at to help me build useful applications that are a bit beyond the millions of console applications I must've written thus-far? Should I be looking at books specifically on learning/working with the .NET framework, or just biting my lip and continue working through open source projects until they start to make sense?

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• strlen returns incorrect value when called in gdb

  - by alesplin

  So I'm noticing some severely incorrect behavior from calls to standard library functions inside GDB. I have the following program to illustrate: #include <stdio.h> #include <stdlib.h> #include <string.h> int main(int argc, char *argv[]) { char *s1 = "test"; char *s2 = calloc(strlen("test")+1,sizeof(char)); snprintf(s2,strlen("test")+1,"test"); printf("string constant: %lu\n", strlen(s1)); printf("allocated string: %lu\n", strlen(s2)); free(s2); return 0; } When run from the command-line, this program outputs just what you'd expect: string constant: 4 allocated string: 4 However, in GDB, I get the following, incorrect output from calls to strlen(): (gdb) p strlen(s1) $1 = -938856896 (gdb) p strlen(s2) $2 = -938856896 I'm pretty sure this is a problem with glibc shipped with Ubuntu (I'm using 10.10), but this is a serious problem for those of us who spend lots of time in GDB. Is anyone else experiencing this kind of error? What's the best way to fix it? Build glibc from source? (I'm already running a version of GDB built from source)

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• Lazy Processing of Streams

  - by Giorgio

  I have the following problem scenario: I have a text file and I have to read it and split it into lines. Some lines might need to be dropped (according to criteria that are not fixed). The lines that are not dropped must be parsed into some predefined records. Records that are not valid must be dropped. Duplicate records may exist and, in such a case, they are consecutive. If duplicate / multiple records exist, only one item should be kept. The remaining records should be grouped according to the value contained in one field; all records belonging to the same group appear one after another (e.g. AAAABBBBCCDEEEFF and so on). The records of each group should be numbered (1, 2, 3, 4, ...). For each group the numbering starts from 1. The records must then be saved somewhere / consumed in the same order as they were produced. I have to implement this in Java or C++. My first idea was to define functions / methods like: One method to get all the lines from the file. One method to filter out the unwanted lines. One method to parse the filtered lines into valid records. One method to remove duplicate records. One method to group records and number them. The problem is that the data I am going to read can be too big and might not fit into main memory: so I cannot just construct all these lists and apply my functions one after the other. On the other hand, I think I do not need to fit all the data in main memory at once because once a record has been consumed all its underlying data (basically the lines of text between the previous record and the current record, and the record itself) can be disposed of. With the little knowledge I have of Haskell I have immediately thought about some kind of lazy evaluation, in which instead of applying functions to lists that have been completely computed, I have different streams of data that are built on top of each other and, at each moment, only the needed portion of each stream is materialized in main memory. But I have to implement this in Java or C++. So my question is which design pattern or other technique can allow me to implement this lazy processing of streams in one of these languages.

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• Determine Better Coding Practice

  - by footprint.

  As a new programmer, it has always been hard to create applications, because I am still at the learning stage. I understand that to achieve a particular affect or function in an application, there will be numerous ways to achieve the same result. However, should I just purely create a function to it's working state, which means that as long as it works, just as the way I want it to, then it should be fine. Can any fellow programmers of a higher level kindly let me know the right way of doing things?

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• How should UI layer pass user input to BL layer?

  - by BornToCode

  I'm building an n-tier application, I have UI, BL, DAL & Entities (built from POCO) projects. (All projects have a reference to the Entities). My question is - how should I pass user input from the UI to the BL, as a bunch of strings passed to the BL method and the BL will build the object from the parameters, or should I build the objects inside the UI submit_function and send objects as parameters? EDIT: I wrote n-tier application, but what I actually meant was just layers.

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• Collaborative Filtering Techniques

  - by user95261

  Good Day! I am in need of help about collaborative filtering techniques implementation in predicting psychopathy of twitter users. I have two data set, training set and test set. Training set users have already scores in psychopathy, I need any collaborative filtering techniques to predict scores of test set users. Collaborative Filtering such as Item/User-Based CF, Bayesian Belief Nets, Clustering, Latent Semantic, etc. Please help me. :( I am very confused on how to implement any of these. Thank you!

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• Pending and Approval process

  - by zen

  So let's say I have a DB table with 8 columns, one is a unique auto-incrementing used as ID. So I have a page that pulls in the info for each row based on query string ID. I want to give my users the ability to propose changes. Kinda like a wiki setup. So I was thinking I should just have another duplicate table or maybe database altogether (without the auto-incrementing column and maybe with a date edited column) that keeps all proposed changes in queue and then when I approve them, the script can move the row from the proposed DB to the real DB. Does this sound good or is there a better process for this?

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• How do I implement powerups for my Breakout clone?

  - by Eva

  I'm making a simple Breakout clone in Python that will have very many powerups/powerdowns (so far I came up with 26). Some will affect the paddle (paddle missile, two paddles, short paddle, etc.), some will affect the ball (slow ball, destructo-ball, invisible ball, etc.), some will affect the bricks (brick scramble, move up, bricks indestructible, etc.), and some will affect other game aspects (extra life, more points, less points, etc.). I'm pretty sure I have the code to draw the falling powerups and test for collisions with the paddle down, but I'm confused about how to code the effects of the powerups. Since there are very many powerups, it seemed inefficient to add specific methods to each component as done in this tutorial. However, I can't think of an other ways to implement the powerups. I found a page that hints at some way to design powerup behavior using classes, but I'm at a loss for how to do that. (A short example would help.) Please give me a short code example of another way to implement the effects of the powerups.

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• Writing generic code when your target is a C compiler

  - by enobayram

  I need to write some algorithms for a PIC micro controller. AFAIK, the official tools support either assembler or a subset of C. My goal is to write the algorithms in a generic and reusable way without losing any runtime or memory performance. And if possible, I would like to do this without increasing the development time much and compromising the readability and maintainability much either. What I mean by generic and reusable is that I don't want to commit to types, array sizes, number of bits in a bit field etc. All these specifications, IMHO, point to C++ templates, but there's no compiler for it for my target. C macro metaprogramming is another option, but, again my opinion, that greatly reduces readability and increases development time. I believe what I'm looking for is a decent C++ to C translator, but I'd like to hear anything else that satisfies the above requirements. Maybe a translator from another high-level language to C that produces very efficient code, maybe something else. Please note that I have nothing against C, I just wish templates were available in it.

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• Using "public" vars or attributes in class calls, functional approach

  - by marw

  I was always wondering about two things I tend to do in my little projects. Sometimes I will have this design: class FooClass ... self.foo = "it's a bar" self._do_some_stuff(self) def _do_some_stuff(self): print(self.foo) And sometimes this one: class FooClass2 ... self.do_some_stuff(foo="it's a bar") def do_some_stuff(self, foo): print(foo) Although I roughly understand the differences between functional and class approaches, I struggle with the design. For example, in FooClass the self.foo is always accessible as an attribute. If there are numerous calls to it, is that faster than making foo a local variable that is passed from method to method (like in FooClass2)? What happens in memory in both cases? If FooClass2 is preferred (ie. I don't need to access foo) and other attributes inside do not change their states (the class is executed once only and returns the result), should the code then be written as a series of functions in a module?

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• Rhythmbox plugin code for hot key not working - why?

  - by Bunny Rabbit

  def activate(self,shell): self.shell = shell self.copy_selected() self.action = gtk.Action ('foo','bar','baz',None) self.activate_id = self.action.connect ('activate', self.call_bk_fn,self.shell) self.action_group = gtk.ActionGroup ('hot_key_action_group') self.action_group.add_action_with_accel (self.action, "<control>E") uim = shell.get_ui_manager () uim.insert_action_group (self.action_group, 0) uim.ensure_update () def call_bk_fn(): print('hello world') I am using the above code in a plugin for Rhythmbox and here I am trying to register the key Ctrl+E so that the call_bk_fn gets called whenever the key combination is pressed but its not working. Why is that so ?

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• How to avoid the GameManager god object?

  - by lorancou

  I just read an answer to a question about structuring game code. It made me wonder about the ubiquitous GameManager class, and how it often becomes an issue in a production environment. Let me describe this. First, there's prototyping. Nobody cares about writing great code, we just try to get something running to see if the gameplay adds up. Then there's a greenlight, and in an effort to clean things up, somebody writes a GameManager. Probably to hold a bunch of GameStates, maybe to store a few GameObjects, nothing big, really. A cute, little, manager. In the peaceful realm of pre-production, the game is shaping up nicely. Coders have proper nights of sleep and plenty of ideas to architecture the thing with Great Design Patterns. Then production starts and soon, of course, there is crunch time. Balanced diet is long gone, the bug tracker is cracking with issues, people are stressed and the game has to be released yesterday. At that point, usually, the GameManager is a real big mess (to stay polite). The reason for that is simple. After all, when writing a game, well... all the source code is actually here to manage the game. It's easy to just add this little extra feature or bugfix in the GameManager, where everything else is already stored anyway. When time becomes an issue, no way to write a separate class, or to split this giant manager into sub-managers. Of course this is a classical anti-pattern: the god object. It's a bad thing, a pain to merge, a pain to maintain, a pain to understand, a pain to transform. What would you suggest to prevent this from happening?

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• Why does Scala require functions to have explicit return type?

  - by garbage collection

  I recently began learning to program in Scala, and it's been fun so far. I really like the ability to declare functions within another function which just seems to intuitive thing to do. One pet peeve I have about Scala is the fact that Scala requires explicit return type in its functions. And I feel like this hinders on expressiveness of the language. Also it's just difficult to program with that requirement. Maybe it's because I come from Javascript and Ruby comfort zone. But for a language like Scala which will have tons of connected functions in an application, I cannot conceive how I brainstorm in my head exactly what type the particular function I am writing should return with recursions after recursions. This requirement of explicit return type declaration on functions, do not bother me for languages like Java and C++. Recursions in Java and C++, when they did happen, often were dealt with 2 to 3 functions max. Never several functions chained up together like Scala. So I guess I'm wondering if there is a good reason why Scala should have the requirement of functions having explicit return type?

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• What Shading/Rendering techniques are being used in this image?

  - by Rhakiras

  My previous question wasn't clear enough. From a rendering point of view what kind of techniques are used in this image as I would like to apply a similar style (I'm using OpenGL if that matters): http://alexcpeterson.com/ My specific questions are: How is that sun glare made? How does the planet look "cartoon" like? How does the space around the planet look warped/misted? How does the water look that good? I'm a beginner so any information/keywords on each question would be helpful so I can go off and learn more. Thanks

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• The need for source control software - Team Foundation Server? or something different?

  - by l0Ft

  Recently, Here at the company, more than one programmer was appointed in charge for a LightSwitch(C#) software development project and immediately there was a need of some sort of source control/sync. We have never used Team Foundation Server but we'd gladly use it if it's worth it. Is it the right tool to use for synchronising code between programmers? Does it have the needed features? Do you have any other tool in mind? (I have used TortoiseSVN but it was too simple and 'texty' if you know what I mean, we need a professional tool) What other features does Team Foundation has that we can use? (if you did not understand any of the above please ask me to clarify further)

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• Do first-class methods exist?

  - by gdhoward

  Okay, I know first-class functions are cool, closures even better, etc. But is there any language with first-class methods? In my mind, I see a first-class method as an "object" that has both a function pointer and a pointer to a specific instance of the class/object, but the implementation doesn't matter. I just want to know if there is any language that uses them. And as a bonus, how were they implemented?

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• Expected time for lazy evaluation with nested functions?

  - by Matt_JD

  A colleague and I are doing a free R course, although I believe this is a more general lazy evaluation issue, and have found a scenario that we have discussed briefly and I'd like to find out the answer from a wider community. The scenario is as follows (pseudo code): wrapper => function(thing) { print => function() { write(thing) } } v = createThing(1, 2, 3) w = wrapper(v) v = createThing(4, 5, 6) w.print() // Will print 4, 5, 6 thing. v = create(7, 8, 9) w.print() // Will print 4, 5, 6 because "thing" has now been evaluated. Another similar situation is as follows: // Using the same function as above v = createThing(1, 2, 3) v = wrapper(v) w.print() // The wrapper function incestuously includes itself. Now I understand why this happens but where my colleague and I differ is on what should happen. My colleague's view is that this is a bug and the evaluation of the passed in argument should be forced at the point it is passed in so that the returned "w" function is fixed. My view is that I would prefer his option myself, but that I realise that the situation we are encountering is down to lazy evaluation and this is just how it works and is more a quirk than a bug. I am not actually sure of what would be expected, hence the reason I am asking this question. I think that function comments could express what will happen, or leave it to be very lazy, and if the coder using the function wants the argument evaluated then they can force it before passing it in. So, when working with lazy evaulation, what is the practice for the time to evaluate an argument passed, and stored, inside a function?

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• What type of application is this called?

  - by boatingcow

  I am working on a web-based application which combines elements of what my client would call a CMS (content management system) and CRM (customer relations management) but also adds in many other business-specific features such as bookings management, staff task allocation management, wages calculations, document version control etc. However, I'm struggling to find a catch-all term for this type of application so I can research how other people have gone about creating such an integrated solution. Can anyone recommend a term I can use to refer to this, both internally in our team, for the client so they know what to call the 'system' and also for me personally, so that I can ask the Stack community further questions?

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• Learning to program in the modern era?

  - by BBHorus

  At this time, lets say in the modern era, in which order do you organize a programing course for teaching and/or learning, what should be learned first, what should emphasize: Databases Data structures Design patterns Programing paradigms(Procedural, functional, OOP, ...etc ) Operating System Some specific programing language What about English if you are not native speaker or doesn't know English AI Anything else... I ask this because in the university that I went, the programing course was awful it was not focus on what you were going to see out when you work what you were supposed to learn. PS: Again sorry about my English is not my main language. ...Experts and gurus please share

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• Could a singleton type replace static methods and classes?

  - by MKO

  In C# Static methods has long served a purpose allowing us to call them without instantiating classes. Only in later year have we became more aware of the problems of using static methods and classes. They can’t use interfaces They can’t use inheritance They are hard to test because you can’t make mocks and stubs Is there a better way ? Obviously we need to be able to access library methods without instantiated classes all the time otherwise our code would become pretty cluttered One possibly solution is to use a new keyword for an old concept: the singleton. Singleton’s are global instances of a class, since they are instances we can use them as we would normal classes. In order to make their use nice and practical we'd need some syntactic sugar however Say that the Math class would be of type singleton instead of an actual class. The actual class containing all the default methods for the Math singleton is DefaultMath, which implements the interface IMath. The singleton would be declared as singleton Math : IMath { public Math { this = new DefaultMath(); } } If we wanted to substitute our own class for all math operations we could make a new class MyMath that inherits DefaultMath, or we could just inherit from the interface IMath and create a whole new Class. To make our class the active Math class, you'd do a simple assignment Math = new MyMath(); and voilá! the next time we call Math.Floor it will call your method. Note that for a normal singleton we'd have to write something like Math.Instance.Floor but the compiler eliminates the need for the Instance property Another idea would be to be able to define a singletons as Lazy so they get instantiated only when they're first called, like lazy singleton Math : IMath What do you think, would it have been a better solution that static methods and classes? Is there any problems with this approach?

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• Are there any reliable solutions for annotations/reflection/code-metadata in C?

  - by dukeofgaming

  Not all languages support java-like annotations or C#-like attributes or code metadata in general, however that doesn't mean it is not possible to have in languages that don't have this. An example is PHP with Stubbles and the Doctrine annotation library. My question is, is there anything like this for C?, or are there any reliable ways of doing reflection with extended code metadata in C? Ideally, I'm looking for something that reads javadoc-like comments. Edit: The reason for me *needing* as opposed to just wanting, is that I need to generate C code and code-metadata from a database, as well as being able to edit that metadada and update the database. The volume of the work (~15,000 variables/structures/functions to generate from this database) justifies the solution.

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• opengl memory issue - quite strange.

  - by user4707

  Hello, I have heard that textures consumes lot of memory but I am surprised how much.... I have 7 textures 1024 16 bit each. And while I will run my app it consumes 57MB of memory. I think that this is "a bit" too much. I am writing 2D application (no cocos or other framework) Strange is that while I will compile my app with disabled rendering methods: glDrawArrays than It uses only 27MB.... which is about 30MB less... Do you have any Idea why? I am creating textures before rendering of course: rendering looks like this: [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer); glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); TeksturaObrazek *obrazek_klaw =[[AppDirector sharedAppDirector] obrazek_klaw]; glBindTexture(GL_TEXTURE_2D, [[obrazek_klaw image_texture] name] ); glVertexPointer(2, GL_FLOAT, 0,vertex1); glTexCoordPointer(2, GL_FLOAT, 0, vertex2); glColor4f(1,1,1,alpha); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisable(GL_BLEND); glDisable(GL_TEXTURE_2D); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glPopMatrix(); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; It looks like standard routine... I have spent about 2 days looking for for answer and I still have no clue.

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• Entry level engineer question regarding memory management

  - by Ealianis

  It has been a few months since I started my position as an entry level software developer. Now that I am past some learning curves (e.g. the language, jargon, syntax of VB and C#) I'm starting to focus on more esoteric topics, as to write better software. A simple question I presented to a fellow coworker was responded with "I'm focusing on the wrong things." While I respect this coworker I do disagree that this is a "wrong thing" to focus upon. Here was the code (in VB) and followed by the question. Note: The Function GenerateAlert() returns an integer. Dim alertID as Integer = GenerateAlert() _errorDictionary.Add(argErrorID, NewErrorInfo(Now(), alertID)) vs... _errorDictionary.Add(argErrorID, New ErrorInfo(Now(), GenerateAlert())) I originally wrote the latter and rewrote it with the "Dim alertID" so that someone else might find it easier to read. But here was my concern and question: Should one write this with the Dim AlertID, it would in fact take up more memory; finite but more, and should this method be called many times could it lead to an issue? How will .NET handle this object AlertID. Outside of .NET should one manually dispose of the object after use (near the end of the sub). I want to ensure I become a knowledgeable programmer that does not just rely upon garbage collection. Am I over thinking this? Am I focusing on the wrong things?

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• Top X tips to code & debug efficiently [closed]

  - by user1510230

  I'm starting a big Java project and I wanted to have some advices that could benefit us all. What are the X (X could be 5 / 10 / ... or even 100 :) most important tips to code and debug efficiently in general (and in particular with java / javascript) ? I'll start with some basic ones : Use functions everytime a portion of code is used more than twice. Try not to code features with more than 15 lines of code in one shot. Rather write 5 lines of code then check if they work correctly then write 5 more... and so on start with the outcome of the function and then code it backwards (bottom-top approach) ... Thanks everybody

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