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  • What to do if exec() fails?

    - by Grigory
    Let's suppose we have a code doing something like this: int pipes[2]; pipe(pipes); pid_t p = fork(); if(0 == p) { dup2(pipes[1], STDOUT_FILENO); execv("/path/to/my/program", NULL); ... } else { //... parent process stuff } As you can see, it's creating a pipe, forking and using the pipe to read the child's output (I can't use popen here, because I also need the PID of the child process for other purposes). Question is, what should happen if in the above code, execv fails? Should I call exit() or abort()? As far as I know, those functions close the open file descriptors. Since fork-ed process inherits the parent's file descriptors, does it mean that the file descriptors used by the parent process will become unusable?

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  • How I can move table to another filegroup ?

    - by denisioru
    Hello, I have MSSQL 2008 Ent and OLTP database with two big tables. How I can move this tables to another filegroup without service interrupting? Now, about 100-130 records inserted and 30-50 records updated each second in this tables. Each table have about 100M records and six fields (including one field geography). I looking for solution via google, but all solutions contain "create second table, insert rows from first table, drop first table, bla bla bla". Can I use partitioning functions for solving this problem? Thank you.

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  • How to check for C++ copy ellision

    - by Steve
    I ran across this article on copy ellision in C++ and I've seen comments about it in the boost library. This is appealing, as I prefer my functions to look like verylargereturntype DoSomething(...) rather than void DoSomething(..., verylargereturntype& retval) So, I have two questions about this Google has virtually no documentation on this at all, how real is this? How can I check that this optimization is actually occuring? I assume it involves looking at the assembly, but lets just say that isn't my strong suit. If anyone can give a very basic example as to what successful ellision looks like, that would be very useful I won't be using copy ellision just to prettify things, but if I can be guaranteed that it works, it sounds pretty useful.

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  • copy C'tor with operator= | C++

    - by user2266935
    I've got this code here: class DerivedClass : public BaseClass { SomeClass* a1; Someclass* a2; public: //constructors go here ~DerivedClass() { delete a1; delete a2;} // other functions go here .... }; My first question is as follows: Can I write an "operator=" to "DerivedClass" ? (if your answer is yes, could you show me how?) My second question is: If the answer to the above is yes, could you show me how to make an "copy c'tor" using the "operator=" that you wrote beforehand (if that is even possible)? Your help would be much appreciated !

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  • C++ conversion operator between types in other libraries

    - by Dave
    For convenience, I'd like to be able to cast between two types defined in other libraries. (Specifically, QString from the Qt library and UnicodeString from the ICU library.) Right now, I have created utility functions in a project namespace: namespace MyProject { const icu_44::UnicodeString ToUnicodeString(const QString& value); const QString ToQString(const icu_44::UnicodeString& value); } That's all well and good, but I'm wondering if there's a more elegant way. Ideally, I'd like to be able to convert between them using a cast operator. I do, however, want to retain the explicit nature of the conversion. An implicit conversion should not be possible. Is there a more elegant way to achieve this without modifying the source code of the libraries? Some operator overload syntax, perhaps?

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  • NotificationCenter Widget Failed To Use CoreLocation

    - by James Ye
    I'm writing a notification center widget, and it had to use location information. In normal apps I use CoreLocation and it works fine. But in my widget, I tried to locationServicesEnabled but it didn't go to the callback functions, and the authorizationStatus is always kCLAuthorizationStatusNotDetermined, and the authorize setting didn't show up in Setting - location service. I already set the delegate to the class. The system's Yahoo weather widget can auto locating and it uses CoreLocation too, so the widget do have ability to use location service. Why CoreLocation doesn't work on my widget?

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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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  • Alternatives to sign() in sqlite for custom order by

    - by Pentium10
    I have a string column which contains some numeric fields, but a lot are 0, empty string or null. The rest are numbers having different range, all positive. I tried to create a custom order by. The order would be done by two fields. First I would like to order the fields that have this number 0 and then sort by name. So something this would work: select * from table order by sign(referenceid) desc, name asc; But Sqlite lacks the sign() -1/0/1 function, and I am on Android and I can't create user defined functions. What other options I have to get this sort done.

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  • Is there any way to retrieve a float from a varargs function's parameters?

    - by Jared P
    If the function was defined with a prototype which explicitly stated the types of the parameters, eg. void somefunc(int arg1, float arg2); but is implemented as void somefunc(int arg1, ...) { ... } is it possible to use va_arg to retrieve a float? It's normally prevented from doing this because varargs functions have implicit type promotions, like float to double, so trying to retrieve an unpromoted type is unsupported, even though the function is being called with the unpromoted type do to the more specific function prototype. The reason for this is to retrieve arguments of different types at runtime, as part of an obj-c interpreter, where one function will be reused for all different types of methods. This would be best as architecture independent (so that if nothing else the same code works on simulator and on device), although if there is no way to do this then device specific fixes will be accepted.

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  • JavaScript pack("d") - binary strings

    - by Tim Whitlock
    I'm trying to replicate the Perl and PHP style pack and unpack functions in JavaScript. Unsigned integers were easy enough, so my pack('n') and pack('N') are ok. But my lack of a computer science background is a hurdle now and I don't know where to start with pack('d') for packing JavaScript's standard floating point. Is there a JavaScript library for this out there? If not, is there a good resource where I can learn how to do this? I am fine with bitwise and binary level operations in JS, I just don't know where to start with the logic. Thanks.

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  • Unexpected result from reduce function

    - by StackedCrooked
    I would like to get the smallest element from a vector. For this I use combine the reduce and min functions. However, when providing my own implementation of min I get unexpected results: user=> (reduce (fn [x y] (< x y) x y) [1 2 3 2 1 0 1 2]) 2 user=> (reduce min [1 2 3 2 1 0 1 2 3]) 0 The reduce with standard min returns 0 as expected. However, when I provide my own implementation it returns 2. What am I doing wrong?

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  • What is the best way to expose a callback API - C++

    - by rursw1
    Hi, I have a C++ library that should expose some system\ resource calls as callbacks from the linked application. For example: the interfacing application (which uses this library) can send socket management callback functions - send, receive, open, close etc., and the library will use this implementation in stead of the library's implementation. (This way enables the application to manage the sockets by itself, can be useful). This library has to expose also more callbacks, like, for example, a password validation, so I wonder if there is a preferred method to expose the callback sending option in one API. Something like: int AddCallbackFunc (int functionCallbackType, <generic function prototype>, <generic way to pass some additional arguments>) Then within my library I will assign the callback to the appropriate function pointer according to the functionCallbackType parameter. Is there any way to implement it in a generic way which will fit ANY function prototype and ANY additional arguments? Your help will be more than appreciated... Thanks!

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  • How to list all items in custom taxonomy with a permanlink in Wordpress

    - by Constant M
    Hi, Not sure how to word this. I've set up a type in Wordpress called Products. I also have two taxonomies linked to Products called Brands and Categories. When you create a product you can set to which Brand and Category the product belong to. It works perfectly when using the type as permalink to list everything within a type http://sitename.com/products but I can't seem to get the taxonomies working in the same way, ie. list all the items within a taxonomy (like an archive, I suppose): http://sitename.com/brands http://sitename.com/categories Is this possible, and if so, what could I possibly be doing wrong? I would try and set up some rewrite rules in functions.php, but I don't know what the query string looks like if you want to list items in a taxonomy, and if this is even possible. If it helps, I'm using the plugins More Types and Ultimate Taxonomy Manager to create the types and taxonomies.

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  • Getting started with a facebook application

    - by Cyclone
    I'm really new to Facebook application development, and I'm quite confused about application permissions and why the php sdk is so limiting and has so few precoded functions. First off, how do I check if a user has set proper permissions for my application, and if not, display that standard dialog immediately instead of using FBML and making them click the link? Secondly, how do I publish to a user's stream with the php apis? Finally, are there any good tutorial sites for making a php based canvas application that use the latest versions of all the sdks? Thank you for your help! I really don't see why so much of this is Javascript, it would really make much more sense to me to have things like: if(!$facebook->appHasPerm('publish_stream'){$facebook->showPermDialog('publish_stream');} I'd feel like I have much more control over the application if it worked like that.

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  • Profiling help required

    - by Mick
    I have a profiling issue - imagine I have the following code... void main() { well_written_function(); badly_written_function(); } void well_written_function() { for (a small number) { highly_optimised_subroutine(); } } void badly_written_function() { for (a wastefully and unnecessarily large number) { highly_optimised_subroutine(); } } void highly_optimised_subroutine() { // lots of code } If I run this under vtune (or other profilers) it is very hard to spot that anything is wrong. All the hotspots will appear in the section marked "// lots of code" which is already optimised. The badly_written_function() will not be highlighted in any way even though it is the cause of all the trouble. Is there some feature of vtune that will help me find the problem? Is there some sort of mode whereby I can find the time taken by badly_written_function() and all of its sub-functions?

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  • Is there any free, open source php CMS\framework for described case?

    - by Ole Jak
    I want that cms\framework to create me tables like "Users" "Cameras" and so on and declare classes and simple default methods for them (like paged sql relults and so on). I mean I say to it: I want Users to have ID, SpecialNumber and Name Flilds. and I want to get from it class for table generation (to call it once) and class containing methods such as Search by ID, SpecialNumber and Name, Create User, Delit User and so on functions. Is there any framework/cms like this for working with CODE not ui's and so on... so to say PHP generator or something... The result should be as that framework free as possible. So Is there any free, open source php CMS\framework for described case?

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  • Combining the value of GetLastError and a custom error message

    - by Jessica
    I have a function that returns a different DWORD value for each case there is an error. So I have the following defines: #define ERR_NO_DB_CONNECTION 0x90000 #define ERR_DB_NOT_OPEN 0x90001 #define ERR_DB_LOCKED 0x90002 #define ERR_DB_CONN_LOST 0x90003 Now, I return those values when an error occurs. I need to also return the value of GetLastError in the same return. No, I can't read it later. I tried combining it different ways, eg: return ERR_DB_NOT_OPEN + GetLastError(); and then extract the error by subtracting the value of ERR_DB_NOT_OPEN but since I need to use this in functions where there can be several return values it can get quite complex to do that. Is there any way to achieve this? I mean, combine the value + GetLastError and extract them later? Code is appreciated. Thanks Jess.

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  • jQuery toggle show XHTML Smarty some clahes maybe? It doesn't show..

    - by Kyle Sevenoaks
    Hi, at this page new customer, there is something that it doesn't like, my boss asked me to make a show function that shows the new customer registration when the user clicks on the "ny kunde" button. Here is an example of the code I got working (I'm a jQuery noob). I guess there is some clash between this and the functions already installed on the page, but what? #roundbigboxnykunde is meant to be hidden on the page as on the jsfiddle example, but I have shown it to let you see what else is on the page. Code on my .tpl <button id="button1">&nbsp;</button> {literal} <script src="http://code.jquery.com/jquery-latest.js"></script> <script type="text/javascript"> $(function() { //checkbox $("#button1").click(function()1 $(".newCustomer").toggle("show"); }); });? </script> {/literal} <div class="newCustomer">... Thanks.

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  • portable way to deal with 64/32 bit time_t

    - by MK
    I have some code which is built both on Windows and Linux. Linux at this point is always 32bit but Windows is 32 and 64bit. Windows wants to have time_t be 64 bit and Linux still has it as 32 bit. I'm fine with that, except in some places time_t values are converted to strings. So when time_T is 32 bit it should be done with %d and when it is 64bit with %lld... what is the smart way to do this? Also: any ideas how I may find all places where time_t's are passed to printf-style functions to address this issue?

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  • How to implement a private virtual function within derived classes?

    - by Dane
    Hi, I know why I want to use private virtual functions, but how exactly can I implement them? For example: class Base{ [...] private: virtual void func() = 0; [...] } class Derived1: puplic Base{ void func() { //short implementation is ok here } } class Derived2: puplic Base{ void func(); //long implementation elsewhere (in cpp file) } [...] void Derived2::func() { //long implementation } The first version is ok but not always possible. Isn't the second version simply name hiding? How do you define the Base::func() of Derived2, if you cannot do it within the class declaration of Dereived2? Thanks

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  • remove spaces in string using javascript

    - by reza saberi
    I need to do some functions on some text field contents before submitting the form, like checking the validity of the customer registeration code, having the customer name as his code in customers table appending an incrementing number. I don't want to do it after the form is submitted becuase I need it to be displayed in the code field before submitting the form. My code: function getCode(){ var temp = document.getElementById("temp").value ; var d = parseInt(document.getElementById("temp").value) + 1; document.getElementById("customernumber").value = d; document.getElementById("code").value = document.getElementById("name").value+"-"+ d; } It all works fine, but the last line of code developed the code WITH the spaces between the code.

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  • Return from parent sub in Perl

    - by JS Bangs
    I want to write a subroutine which causes the caller to return under certain conditions. This is meant to be used as a shortcut for validating input to a function. What I have so far is: sub needs($$) { my ($condition, $message) = @_; if (not $condition) { print "$message\n"; # would like to return from the *parent* here } return $condition; } sub run_find { my $arg = shift @_; needs $arg, "arg required" or return; needs exists $lang{$arg}, "No such language: $arg" or return; # etc. } The advantage of returning from the caller in needs would then be to avoid having to write the repetitive or return inside run_find and similar functions.

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  • How to use YT thumb in plugin

    - by Frank Morrison
    I'm using two plugins on my wordpress site: Auto post youtube Pulls a youtube video then drafts it for me. I use this on my index page beside the post code and the thumbnail appears great: <?php tern_wp_youtube_image(); ?> Top Ten Which I use to display the most viewed posts on a page. Not looking great at the moment, but will fix styling later. This is the code to display popular posts: <?php if(function_exists('tptn_show_pop_posts')) tptn_show_pop_posts(); ?> Is it possible for me to use the youtube image in the popular post function? Or is it because they are seperate they cannot work together without a lot of code? Thanks in advance! Some links incase anybody wants to check them out http://wordpress.org/extend/plugins/top-10/ http://www.ternstyle.us/products/plugins/wordpress/wordpress-automatic-youtube-video-posts/wordpress-automatic-youtube-video-posts-functions

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  • Confused by "let" in Clojure

    - by Tom Dalling
    I just started playing with Clojure, and I wrote a small script to help me understand some of the functions. It begins like this: (def *exprs-to-test* [ "(filter #(< % 3) '(1 2 3 4 3 2 1))" "(remove #(< % 3) '(1 2 3 4 3 2 1))" "(distinct '(1 2 3 4 3 2 1))" ]) Then it goes through *exprs-to-test*, evaluates them all, and prints the output like this: (doseq [exstr *exprs-to-test*] (do (println "===" (first (read-string exstr)) "=========================") (println "Code: " exstr) (println "Eval: " (eval (read-string exstr))) ) ) The above code is all working fine. However, (read-string exstr) is repeated so I tried to use let to eliminate the repetition like so: (doseq [exstr *exprs-to-test*] (let [ex (read-string exstr)] ( (do (println "===" (first ex) "=========================") (println "Code: " exstr) (println "Eval: " (eval ex)) ) )) ) But this works once for the first item in *exprs-to-test*, then crashes with a NullPointerException. Why is the addition of let causing the crash?

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  • qt custom widgets propertis are not getting updated properly in Qt designer

    - by user553911
    I have created a custom widget. The widget gets loaded fine,the properties appear in QT Designer, Only problem is every time I change the property of Alpha key,the numeric also gets set, Though the accessor functions are different,and the enums are differnet and values are different. Also whenever i check the Form-view code,the values would have got modified. Am i Missing something or this is a designer issue,Any workarounds would be appreciated class key { Q_PROPERTY(AlphKeycode_t AlphKeycode READ AlphKeycode WRITE setAlphKeycode); Q_PROPERTY(bool AlphKey READ isAlph WRITE setAlph); Q_ENUMS(AlphKeycode_t); Q_PROPERTY(NumKeycode_t NumKeycode READ NumeKeycode WRITE setNumKeycode); Q_PROPERTY(bool NumKey READ isNum WRITE setNum); Q_ENUMS(NumKeycode_t); } struct AlphData { QString label; bool isAlphabetic; }; struct NumData { QString label; bool isNumeric; }; AlphData AlphKeyData[] = { {"q",true }, } NumData NumKeyData[] = { {"1", false}, }

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