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  • Implement abstract class as a local class? pros and cons

    - by sinec
    Hi, for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } the reason why I'm doing this are: I'm lazy to implement class (B) in separate files MethodToOverride just delegates call to other class Class B shouldn't be visible to other users no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!

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  • Order of execution and style of coding in Python

    - by Jason
    Hi guys. I am new to Python so please don't flame me if the question is too basic :) I have read that Python is executed from top - to - bottom. If this is the case, why do programs go like this: def func2(): def func1(): #call func2() def func() #call func1() if __name__ == '__main__': call func() So from what I have seen, the main function goes at last and the other functions are stacked on top of it. Am I wrong in saying this? If no, why isn't the main function or the function definitions written from top to bottom?

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  • Any good idioms for error handling in straight C programs?

    - by Will Hartung
    Getting back in to some C work. Many of my functions look like this: int err = do_something(arg1, arg2, arg3, &result); With the intent the result gets populated by the function, and the return value is the status of the call. The darkside is you get something naive like this: int err = func1(...); if (!err) { err = func2(...); if (!err) { err = func3(...); } } return err; I could macro it I suppose: #define ERR(x) if (!err) { err = (x) } int err = 0; ERR(func1(...)); ERR(func2(...)); ERR(func3(...)); return err; But that only works if I'm chaining function calls, vs doing other work. Obviously Java, C#, C++ have exceptions that work very well for these kinds of things. I'm just curious what other folks do and how other folks do error handling in their C programs nowadays.

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  • i need help to designe code in c++

    - by user344987
    ) Design and implement a Graph data structure. Use adjacency matrix to implement the unweighted graph edges. The Graph must support the following operations: 1.Constructor 2.Destructor 3.Copy constructor 4.A function to add an edge between two nodes in the graph 5.A display function that outputs all the edges of the graph 6.A function edge that accepts two nodes, the function returns true if there is an edge between the passed nodes, and returns false otherwise. B.(100 points) Depth first search and Breadth first search functions. C.(100 points) A function to output a spanning tree of the graph, use any algorithm you find appropriate, also, make the necessary changes on the data structure in A to implement your algorithm.

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  • Elegant way to distinct Path or Entry key

    - by sum1stolemyname
    I have an application loading CAD data (Custom format), either from the local filesystem specifing an absolute path to a drawing or from a database. Database access is realized through a library function taking the drawings identifier as a parameter. the identifiers have a format like ABC 01234T56-T, while my paths a typical windows Paths (eg x:\Data\cadfiles\cadfile001.bin). I would like to write a wrapper function Taking a String as an argument which can be either a path or an identifier which calls the appropriate functions to load my data. Like this: Function CadLoader(nameOrPath : String):TCadData; My Question: How can I elegantly decide wether my string is an idnetifier or a Path to a file? Use A regexp? Or just search for '\' and ':', which are not appearing in the Identifiers?

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  • writing structs and classes to disk

    - by Phenom
    The following function writes a struct to a file. int btwrite(short rrn, BTPAGE *page_ptr) { long addr; addr = (long) rrn * (long) PAGESIZE + HEADERSIZE; lseek(btfd, addr, 0); return (write(btfd, page_ptr, PAGESIZE)); } The following is the struct. typedef struct { short keycount; /* number of keys in page */ int key[MAXKEYS]; /* the actual keys */ int value[MAXKEYS]; /* the actual values */ short child[MAXKEYS+1]; /* ptrs to rrns of descendants */ } BTPAGE; What would happen if I changed the struct to a class, would it still work the same? If I added class functions, would the size it takes up on disk increase?

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  • DataTable from TextFile?

    - by Craig
    I have taken over an application written by another developer, which reads data from a database, and exports it. The developer used DataTables and DataAdaptors. So, _dataAdapter = new SqlDataAdapter("Select * From C....", myConnection); and then ExtractedData = new DataTable("CreditCards"); _dataAdapter.Fill(ExtractedData); ExtractedData is then passed around to do different functions. I have now been told that I need to, in addition to this, get the same format of data from some comma separated text files. The application does the same processing - it's just getting the data from two sources. So, I am wondering if I can get the data read into a DataTable, as above, and then ADD more records from a CSV file. Is this possible?

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  • How to get available memory C++/g++ ?

    - by Agito
    I want to allocate my buffers according to memory available. Such that, when I do processing and memory usage goes up, but still remains in available memory limits. Is there a way to get available memory (I don't know will virtual or physical memory status will make any difference ?). And method has to be platform Independent as its going to be used on Windows, OS X, Linux and AIX. (And if possible then I would also like to allocate some of available memory for my application, someone it doesn't change during the execution).

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  • C++ Vector at/[] operator speed

    - by sub
    In order to give functions the option to modify the vector I can't do curr = myvec.at( i ); doThis( curr ); doThat( curr ); doStuffWith( curr ); But I have to do: doThis( myvec.at( i ) ); doThat( myvec.at( i ) ); doStuffWith( myvec.at( i ) ); (as the answers of my other question pointed out) I'm going to make a hell lot of calls to myvec.at() then. How fast is it, compared to the first example using a variable to store the result? Is there a different option for me? Can I somehow use pointers? When it's getting serious there will be thousands of calls to myvec.at() per second. So every little performance-eater is important.

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  • Execute a batch script from Firefox

    - by danilo
    I have written an intranet application from which you can directly connect to a virtual machine by clicking on a RDP-button. The click calls a .bat file, which opens the connection. With IE, this is no problem, as you can choose to directly execute the batch file. But with Firefox, I can only download the script, and have to start it manually afterwards. Is there a way to trust the intranet domain (about:config?) so Firefox allows it to execute scripts directly? Or is there an even better (easier) way to start an RDP connection from Firefox?

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  • Initializing a array after declaration

    - by robUK
    Hello, gcc 4.4.3 c89 I have the following code as a sample of what I am trying to do. I don't know the actual size of the array, until I enter the function. However, I don't think I can set the array size after I have declared it. I need it global as some other functions will need to access the device names. Many thanks for any suggestions, /* global */ char *devices_names[]; void fill_devices(size_t num_devices) { devices_names[num_devices]; /* start filling */ }

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  • Per Process Memory Calculation Alogrithm in Linux (say kernel 2.6 and above)

    - by Vaibhav Singh
    How do you calculate the linux process's Acutal Memory Usage and Not Virtual Memory Usage through the information supplied by /proc//smaps or maps or status or stat. To be more precise I need the heap usage only. I need to do this on an PowerPc based embedded system and hence I do not have utilities like exmap, valgrind etc. I understand the concepts of shared/non shared memory. I have read through the other topics given in this forum about the same but they talk more using the tools mentioned. What I need is the native way of calculation done by the same tools so that I may write a shell script for the same.

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  • Does the Internet make us less good programmers? [closed]

    - by stagas
    With all the information and code available nowadays on the Internet has that diminished our capability of remembering or learning stuff just because we know they're available somewhere out there, just a Google away or a StackOverflow question away? For example I find myself visiting php.net quite often to check the syntax of the same functions over and over again, not because my memory sucks, but I don't feel like keeping the information in me, since I know I'll find it again on the net. And about StackOverflow, isn't the process of figuring things out on your own supposed to improve your programming skills? If the answers are all just clicks away, do we actually learn something or just keep a pointer in our heads where to search for it again when we need it? Your thoughts are welcome. Hope it doesn't shut down as subjective or anything, the answers would be really interesting ;)

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  • Add a custom class name to Wordpress body tag?

    - by Scott B
    I'd like to place a directive in my theme's functions.php file which appends a classname to the wordpress body tag. Is there a built-in API method for this? For example, my body tag code is... <body <?php if(function_exists("body_class") && !is_404()){body_class();} else echo 'class="page default"'?>> And it results in the following being written to the body tag (depending on the context in which the page is presented (page, post, logged-in, etc) <body class="home blog logged-in"> Depending on the child theme I'm using at the time, I want it to be... <body class="home blog logged-in mychildthemename">

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  • Qt drag/drop: cannot move when copy is enabled (Ubuntu Gnome)

    - by Scott
    I'm implementing a view and a model where I want to support both moving items internally (by dragging), and copying items (by pressing Ctrl while dragging). I've done everything I need to do according to the instructions. I've set up the mime functions, I've implemented removeRows(), and flags(). The problem is when I drag, it defaults to a copy operation (I get the arrow cursor with a plus sign, and it indeed copies the item by creating a new one in the model). The only difference I can see is this: If I return only Qt::MoveAction in supportedDropActions(), it only moves. If I return (Qt::CopyAction | Qt::MoveAction), it only copies. Any ideas? I want it to work like files in Nautilus (Gnome) or Windows file Explorer: drag moves icons around, ctrl+drag copies them.

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  • Getting imagename and make link from <img> with jQuery

    - by Bulan
    With jQuery, I want to make all images under a specific path on a site clickable and showing a big image using Fancybox, which is a lighbox variant plugin for jQuery. My small images are located under "images/products/small", the big ones under "images/products/big" and the imagename is always the same The page is showing the image with the following code: <img src="images/products/small/hat.jpg" alt="Nice hat"> What i want is some jQuery script that makes this into: <a href="images/products/big/hat.jpg" class="fancybox"><img src="images/products/small/hat.jpg" alt="Nice hat"></a> Maybe the part with setting class on the link tag can be skipped and just activate fancybox on the element directly with $(elm).fancybox(); I was looking around a bit and it looks like the jQuery functions "attr" and "wrap" might be useful, but with my currently limited jQuery skills I can't really connect the dots.

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  • How to reference filtered ng-repeat items from a controller in AngularJS

    - by ParkerDigital
    I have some JSON data that is rendered out via the ng-repeat directive, and the results are then filtered via some checkboxes/drop-downs, and some custom filter functions in my controller. I now want to add a function to my controller that is triggered by an 'ng-change' on some of the checkboxes, that can reference the current list of items in my 'ng-repeat'. I realise I can reference these values from a custom filter, for example $scope.filterProvider = function(item), but this function is then called for each and every item in the ng-repeat, which isn't what I want - I want the function to just be called each time a checkbox is checked/unchecked, and I need that function to be able to reference the items in my ng-repeat...does that make sense to anyone?! And if so, does anyone know how I can do that? Thanks :-)

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  • Is it good to use JQuery's validation plugin?

    - by kwokwai
    Hi all, I am learning JQuery, and I have checked out that JQUery has got a validation plugin. http://docs.jquery.com/Plugins/Validation#Validate_forms_like_you.27ve_never_been_validating_before.21 To use it, users have to include another script file in the Head tag in HTML. I am thinking if this will cause any code collisions to the codes in the validation plugin when more and more javascript files are included. Should I use JQuery to write myself new customed functions for checking data input from users or use the JQuery data validation plugin? Please advise.

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  • How to move to another view without using a button

    - by Will
    My first view displays an image and action indicator while web-servers and database function are run in that background. I want the application to go to my tab view when the functions have been completed. How do I do this? Here is what the views look like. What I have tried: TabBarViewController *tab = [[TabBarViewController alloc]init]; [self presentViewController:tab animated:NO completion:nil]; and [self performSegueWithIdentifier:@"first" sender:self]; Please can you help my to understand how to do this. I have spent many hours googling this problem and couldn't work out how to do it. Thanks EDIT: Added Code

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  • I have some basic questions setting up a PHP daemon

    - by mike
    I will be writing my first daemon in php and I have a couple really basic questions that I need help with. 1) What packages need to be installed on my linux server and Does anything in PHP need to be enabled? So far I have gotten this - http://pear.php.net/package/System_Daemon/download 2) Where on server do I save my daemon files? 3) I have a number of files that need to be included within the daemon that contain classes and functions for gathering emails and attachments through IMAP. All of these files are currently in my web public directory, how do I include these files within my daemon? I think that is everything I need to get started. Thanks so much!

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  • Dynamically udpate canvasOverlay property of jQuery jqPlot

    - by You Kuper
    I want to dynamically udpate canvasOverlay property of jQuery jqPlot. This will provide the effect of a timeline in my jqPlot. This effect should be similar to the one shown in this jFiddle. However, instead of drawing points, I want to update canvasOverlay property every second: canvasOverlay: { show: true, objects: [ { rectangle: { xmax: new Date(), xminOffset: "0px", xmaxOffset: "0px", yminOffset: "0px", ymaxOffset: "0px", color: "rgba(0, 0, 0, 0.1)", showTooltip: true } }, ] } How can I do this? What are the functions I should use? UPDATE: My idea is to do something like this: canvasOverlay: { name: 'current', show: true, objects: [ { rectangle: { xmax: new Date(), xminOffset: "0px", xmaxOffset: "0px", yminOffset: "0px", ymaxOffset: "0px", color: "rgba(0, 0, 0, 0.1)", showTooltip: true } }, ] } /... var co = plot.plugins.canvasOverlay; var current = co.get('current'); current.options.objects.rectangle.xmax = new Date(); co.draw(plot);

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  • Function to set an auth_token

    - by john mossel
    In my form I have a hidden field: <input type="hidden" name="auth_token" value="<?php echo $auth_token; ?>"> This value is also stored in a session and a variable: $_SESSION['auth_token'] = hash('sha256', rand() . time() . $_SERVER['HTTP_USER_AGENT']); # TODO: put this in a function $auth_token = $_SESSION['auth_token']; When the form is submitted the two values are compared. It's a basic form token. Should this be made into two functions or just one when refactored? set_form_token() and get_form_token(), get_form_token() returning the session value, then I can compare it in my main code. What is the proper way of doing this?

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  • Emacs and Long Shell Commands

    - by darrint
    Is there a way to run a shell command, have the output show up in a new buffer and have that output show up incrementally? Eshell and other emacs terminal emulators do a find job of this but I see no way to script them. What I'd like to do is write little elisp functions to do stuff like run unit tests, etc. and watch the output trickle into a buffer. The elisp function shell-command is close to what I want but it shows all the output at once when the process finishes.

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  • Reserved Memory Addresses?

    - by Nate
    Is there a list of reserved memory addresses out there - a list of addresses that the memory of a user-space program could never be allocated to? I realize this is most likely per-OS or per-architecture, but I was hoping someone might know some of the more common OSes and Arches. I could only dig one up for a few versions of windows: for windows NT,2k and XP that would be: 0x00000000 - 0x0000ffff - lowest page is protected to simplify debugging 0x00001000 - 0x7ffeffff - memory area for your application 0x7fff0000 - 0x7fffffff - protected area to keep memory-functions from damaging the following part 0x80000000 - 0xffffffff - memory where the system including drivers and so on is located Anyone know about for Linux, or BSD (or anything else, for that matter)?

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  • Dynamic access to tables from another database inside an user function

    - by Alberto Martinez
    I have an user defined table function in SQL Server that aggregate data from several tables including a couple of tables of another database. That is done hardcoding the name of the database in the queries, but we want to make the database name configurable (because our databases usually share the server with the databases of other applications). I tried to construct a dynamic query string inside the function using the database name that is stored in a configuration table, but: When I tried exec(@sqlStatement) SQL Server said that execute string is not allowed inside a function. Then I tried exec sp_executesql @sqlStatement and the function was created, but when you execute it SQL Server says that inside a function you can only run extended functions and procedures. So the question is: is possible create a function or stored procedure that access a table in another database without having to recreate the function when the database name is different? TIA.

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