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  • Hashing and salting values

    - by Avanst
    I am developing a small web app that internally authenticates users. Once the user is authenticated my web app then passes some information such as userID and Person's name to a third party web application. The third party developer is suggesting that we hash and salt the values. Forgive my ignorance, but what exactly does that mean? I am writing the app in Java. So what I am planning on doing is hashing the userID, Person's name, and some Math.random() value as the salt with Apache Commons Digest Utils SHA512 and passing that hashed string along with the userID and person's name. Is that the standard practice? I should be passing the third party the salt as well correct?

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  • Arrange 0's & 1's in a array

    - by Ganesh M
    This is one of an interview question which I had recently. I would like to know others perception of approach for this problem. Question: You are given a structure which holds an employee details with two elements as int Deptartment and string Name. struct Employee { string Name; int Dept; } You are given details of N Employees among which there are N/2 employees Dept are 0's and N/2 employees dept are 1's arranged in some random order. You need to sort the employee details based on their Dept value and it should be stable i.e., the order of 1s and 0s in the original record should be maintained. For example, given the following sample data: Name Dept X1 0 X2 1 X3 0 X4 1 X5 0 after sorting the result should be: Name Dept X2 1 X4 1 X1 0 X3 0 X5 0 The algorithm should be stable and the complexity should be o(N), with constant space for additional variables (which means sorting should be done in-place).

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  • Extreamely fast way to clone the values of an array into a second array?

    - by George
    I am currently working on an application that is responsible for calculating random permutations of a multidemensional array. Currently the bulk of the time in the application is spent copying the array in each iteration (1 million iterations total). On my current system, the entire process takes 50 seconds to complete, 39 of those seconds spent cloning the array. My array cloning routine is the following: public static int[][] CopyArray(this int[][] source) { int[][] destination = new int[source.Length][]; // For each Row for (int y = 0; y < source.Length; y++) { // Initialize Array destination[y] = new int[source[y].Length]; // For each Column for (int x = 0; x < destination[y].Length; x++) { destination[y][x] = source[y][x]; } } return destination; } Is there any way, safe or unsafe, to achieve the same effect as above, much faster?

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  • Stocket server crashing with unhandled exception

    - by Rob
    We have a c# (3.5 framework) socket server which is a console app, after about 3000 connections (or less, it's quite random), we get an unhandled exception which crashes the app completely. We're really struggling to find out what's happening and where, the only info we get is below, can anyone shed any light? It should be noted that EVERYTHING is wrapped up in try catch{} Description: Stopped working Problem signature: Problem Event Name: CLR20r3 Problem Signature 01: qrushrserver.exe Problem Signature 02: 1.0.0.0 Problem Signature 03: 4bf56a0c Problem Signature 04: System Problem Signature 05: 2.0.0.0 Problem Signature 06: 49cc5ec9 Problem Signature 07: 2c0b Problem Signature 08: 40 Problem Signature 09: System.Net.Sockets.Socket OS Version: 6.0.6002.2.2.0.1296.17 Locale ID: 2057 Faulting application app_name.exe, version 1.0.0.0, time stamp 0x4bf56a0c, faulting module mscorwks.dll, version 2.0.50727.4200, time stamp 0x4a9ee32d, exception code 0xc0000005, fault offset 0x00000000001c89ca, process id 0x%9, application start time 0x%10. .NET Runtime version 2.0.50727.4200 - Fatal Execution Engine Error (000007FEF8E4664E) (80131506)

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  • Same memory space being allocated again & again while using malloc()

    - by shadyabhi
    In each loop iteration, variable j is declared again and again. Then why is its address remaining same? Shouldn't it be given some random address each time? Is this compiler dependent? #include<stdio.h> #include<malloc.h> int main() { int i=3; while (i--) { int j; printf("%p\n", &j); } return 0; } Testrun:- shadyabhi@shadyabhi-desktop:~/c$ gcc test.c shadyabhi@shadyabhi-desktop:~/c$ ./a.out 0x7fffc0b8e138 0x7fffc0b8e138 0x7fffc0b8e138 shadyabhi@shadyabhi-desktop:~/c$

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  • How to change a particular element of a C++ STL vector

    - by cambr
    vector<int> l; for(int i=1;i<=10;i++){ l.push_back(i); } Now, for example, how do I change the 5th element of the vector to -1? I tried l.assign(4, -1); It is not behaving as expected. None of the other vector methods seem to fit. I have used vector as I need random access functionality in my code (using l.at(i)).

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  • Xpath help function

    - by NA
    Hi i have a document from which i am trying to extract a date. But the problem is within the node along with the date their is some text too. Something like <div class="postHeader"> Posted on July 20, 2009 9:22 PM PDT </div> From this tag i just want the date item not the Posted on text. something like ./xhtml:div[@class = 'postHeader'] is getting everything. and to be precise, the document i have is basically a nodelist of this elements for eg i will get 10 nodes of these elements with different date values but to be worse the problem is sometime inside these tags some random other tags also pops us like anchors etc. Can i write a universal expath which will just get the date out of the div tag?

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  • Query syntax error selecting from 3 tables

    - by Toni Michel Caubet
    Given info about an object: id, user_id, group_id Given info about an user: id_user, id_loc I need to get i one query: The name of the user (in table users) The name of the location of the user (in table locs) The name of the group of the object (in table groups) I am trying like this: SELECT usuarios.first_name as username, usuarios.id as userid, usuarios.avatar as useravatar, usuarios.id_loc, locs.name as locname, groups.name as groupname FROM usuarios,groups,locs WHRE usuarios.id_loc = locs.id AND usuarios.id = 1 AND group.id = LIMIT 1 having an error saying You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND locs.id = 3 LIMIT 1' at line 3 What am i doing wrong? can i do this in one query? -EDIT- This is the query generator code (php+mysql): $query_loc_group_user = 'SELECT usuarios.first_name as username, usuarios.id as userid, usuarios.avatar as useravatar, usuarios.id_loc, locs.name as locname, groups.name as groupname FROM usuarios,groups,locs WHRE usuarios.id_loc = locs.id AND usuarios.id = '.$this->id_user.' AND group.id = '.$this->id_group.' LIMIT 1'; In case it helps, i am trying to do in one query this function get_info(){ $info; $result = cache_query('SELECT first_name,last_name,avatar FROM usuarios WHERE id = '.$this->id_user); foreach($result as $extra){ $info['username'] = $extra['first_name'].' '.$extra['last_name']; $info['avatar'] = $extra['avatar']; } $result1 = cache_query('SELECT name FROM locs WHERE id = '.$this->id_user); foreach($result1 as $extra){ $info['locname'] = $extra['name']; } $result2 = cache_query('SELECT name FROM locs WHERE id = '.$this->id_user); foreach($result2 as $extra){ $info['groupname'] = $extra['name']; } return $info; }

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  • For securing forms, when do I issue the token?

    - by AQuestionADayKeepsTheDrAway
    So, I have a form, to make it a little more secure and potentially help prevent CSRF attacks I want to add a random token value in a hidden field that value is also stored server side in my session data. When should I issue a new token? Per form? Per page load where there is any form? Per session? I can render it invalid as soon as a form is successfully submitted but I'm wondering when to generate one. I ask as if I issue it per form or per page do I not risk the chance of a duplicate token value overwriting the existing (valid) token if a user opens a separate window but submitting the first form (with the now overwritten value)?

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  • Scalable way to store files on server (PHP)?

    - by Nathaniel Bennett
    I'm creating my first web application - a really simplistic online text editor. What I need to do is find the best way to store text based files - a lot of them. These text files can be past 10,000 words in size (text words not computer words.) in essence I want the text documents to be limitless in size. I was thinking about storing the text files in my MySQL database - but thought there was a better way. Instead I'm planing on storing the text files in XML based format in a directory on my server. The rows in the database define the name of the xml based text file and the user who created the text along with basic metadata. An ID is generated using a V4 GUID generator , which gives the text an id and stores the text in the "/store" directory on my server. The text definitions in my server contain this id, and the android app I'm developing gets the contents of the text file by retrieving the text definition and then downloading the text to the local device using the GUID in the text definition. I just think this is a botch job? how can I improve this system? There has been cases of GUID colliding. I don't want this to happen. A "slim" possibility isn't good enough - I need to make sure there is absolutely no chance in a GUID collision. I was planning on checking the database for texts that have the same id before storing the text with a particular id - I however believe with over 20,000 pieces of text in my database this would take an long time and produce unneeded stress on the server. How can I make GUID safe? What happens when a GUID collides? The server backend is going to be written in PHP.

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  • Linux How to print all the files with the same prefix after searching for them?

    - by Alyx
    I need to search through a directory which contains many sub directories, each which contain files. The files read as follows question1234_01, where 1234 are random digits and the suffix _01 is the number of messages that contain the prefix, meaning they are apart of the same continuing thread. find . -name 'quest*' | cut -d_ -f1 | awk '{print $1}' | uniq -c | sort -n example output: 1 quest1234 10 quest1523 This searches for all the files then sorts them in order. What I want to do is print all the files which end up having the most occurrences, in my example the one with 10 matches. So it should only output quest1523_01 - 11

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  • Choose between multiple options with defined probability

    - by Sijin
    I have a scenario where I need to show a different page to a user for the same url based on a probability distribution, so for e.g. for 3 pages the distribution might be page 1 - 30% of all users page 2 - 50% of all users page 3 - 20% of all users When deciding what page to load for a given user, what technique can I use to ensure that the overall distribution matches the above? I am thinking I need a way to choose an object at "random" from a set X { x1, x2....xn } except that instead of all objects being equally likely the probability of an object being selected is defined beforehand.

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  • Hibernate Relationship Mapping/Speed up batch inserts

    - by manyxcxi
    I have 5 MySQL InnoDB tables: Test,InputInvoice,InputLine,OutputInvoice,OutputLine and each is mapped and functioning in Hibernate. I have played with using StatelessSession/Session, and JDBC batch size. I have removed any generator classes to let MySQL handle the id generation- but it is still performing quite slow. Each of those tables is represented in a java class, and mapped in hibernate accordingly. Currently when it comes time to write the data out, I loop through the objects and do a session.save(Object) or session.insert(Object) if I'm using StatelessSession. I also do a flush and clear (when using Session) when my line count reaches the max jdbc batch size (50). Would it be faster if I had these in a 'parent' class that held the objects and did a session.save(master) instead of each one? If I had them in a master/container class, how would I map that in hibernate to reflect the relationship? The container class wouldn't actually be a table of it's own, but a relationship all based on two indexes run_id (int) and line (int). Another direction would be: How do I get Hibernate to do a multi-row insert?

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  • Detecting when a process has finished (but not exited)

    - by Egwor
    I have a program that's run in unix (that I have no control over) that when finished prints 'Completed successfully' but does not exit. I want to automatically detect when the process finishes (by checking the output of the command), so that I can kill the process and so that I can proceed do other activities. The complexity comes because I want to be able to run multiples of these scripts concurrently. (One activity I need to do requires the script to be called with various inputs, but each time the script runs it takes a while to return, and so I want to do them in parallel) Has anyone done something similar to this? I could redirect the stderr and stdout output of the command to a temporary file which has a random file name, then tail the file and pipe to grep for the end conditions (I.e. the certain log lines). The problem is, surely tail -f would keep running, and so it would never exit. Should I poll? If so, what's the best approach?

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  • Same memory space being allocated again & again

    - by shadyabhi
    In each loop iteration, variable j is declared again and again. Then why is its address remaining same? Shouldn't it be given some random address each time? Is this compiler dependent? #include<stdio.h> #include<malloc.h> int main() { int i=3; while (i--) { int j; printf("%p\n", &j); } return 0; } Testrun:- shadyabhi@shadyabhi-desktop:~/c$ gcc test.c shadyabhi@shadyabhi-desktop:~/c$ ./a.out 0x7fffc0b8e138 0x7fffc0b8e138 0x7fffc0b8e138 shadyabhi@shadyabhi-desktop:~/c$

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  • SQLce create table "index field" explanation (SQL Management Studio) ?

    - by bretddog
    Hi, I'm new to databases, and now creating SQLCE database in Management Studio. There is a value in brackets; [UQ_Users_0000000000000028], which seems a bit random to me, so would just like to ask if someone could explain this field? Is it just simply required to be a unique field? Is there any reason why I would want to change it to something else than what SSMS scripts? cheers! CREATE TABLE [Users] ( [UserID] int NOT NULL ..... CREATE UNIQUE INDEX [UQ__Users__0000000000000028] ON [Users] ([UserID] ASC);

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  • Looping through with dates

    - by Luke
    I have created a fixture generator for football/ soccer games... $totalRounds = $teams - 1; $matchesPerRound = $teams / 2; $rounds = array(); $roundDates = array(); $curTime = time(); for ($i = 1; $i <= $totalRounds; $i++) { $rounds[$i] = array(); $numDays = $i * 4; $roundDates[$i] = strtotime("+".$numDays." days",$curTime); } foreach($roundDates as $time) { for ($round = 0; $round < $totalRounds; $round++) { for ($match = 0; $match < $matchesPerRound; $match++) { $home = ($round + $match) % ($teams - 1); $away = ($teams - 1 - $match + $round) % ($teams - 1); // Last team stays in the same place while the others // rotate around it. if ($match == 0) { $away = $teams - 1; } $rounds[$round][$match] = "$user[$home]~$team[$home]@$user[$away]~$team[$away]~$time"; } } } In the code, for $i = 1, i thought that if you want the first date 4 days from now, the i must be 1, so 1 * 4 = 4. If i was 0, 0 * 4 equals 0. I assume this is correct thinking? Anyway the main question is, trying to generate the dates isn't working. When i created a fixture list for 4 users home and away, I got 12 fixtures. 10 of these had the same date on them, and the other 2 didnt have a date. Can anyone help me with this? Thanks

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  • Changing the way widgets are rendered/displayed in a form on the template

    - by user334017
    I have a form with a few other embedded forms and some various widgets. The widgets are all saved in an array $form['elements'] and for some of them, I want to display labels and things, but for others I only want to display the basic rendering. foreach($form['elements'] as $elem) echo $elem->render(); this displays everything about the widget. The way it is right now, I couldn't for example call $elem['..'] because the different subforms appear in a random order and have different variable names. I assume I could still put some checks in the template, but it seems easier to fix this in the widget class, like override one of the render functions or something. How would I go about doing this or do you have any links that could help me understand how do do this? on a side note, one of my widgets is the sfWidgetFormChoice and I have no clue where it actually renders or how renderer_classes work

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  • Prevent Apache from answering invalid requests

    - by nickdnk
    I have an Apache web-server that acts as a web front-end for iPhone and iPad applications that communicate by POST and JSON only. Is there any way to prevent Apache from answering requests that are invalid? I can see my error log is filled with attempts to open files such as /admin.php /index.php etc - files that don't exist on my server. I believe this is possible with IIS, but can you do the same thing with Apache? Basically I want the request to appear timed out unless you post exactly the right content to the right file - or at least if you do not request an existing file. This would make the server appear non-existing to everyone but my iPhone users as all communication is SSL and directories are not really guess-able. I did disable the ServerTokens and all that, but I still get File not found etc. when I access the server requesting a random file, which is what these bots do constantly.

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  • How to copy/install assembly in a GAC? (Some problem running NUnit)

    - by prosseek
    I have NUnit installed at this directory. C:\Program Files\NUnit 2.5.5\bin\net-2.0 I made the directory beneath a GAC. C:\Windows\Microsoft.NET\assembly\GAC_MSIL\NUnit and copied the nunit.framework.dll, but I got the same error. When I try to run my unit test (mut.dll) in some random directory. I get the following error. I have to copy the mut.dll under the NUnit directory in order to run it. ProcessModel: Default DomainUsage: Single Execution Runtime: net-2.0 Could not load file or assembly 'nunit.framework, Version=2.5.5.10112, Culture=n eutral, PublicKeyToken=96d09a1eb7f44a77' or one of its dependencies. The system cannot find the file specified. What went wrong? How can I install/copy the assembly inside a GAC?

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  • Layout of popup components changes while moving

    - by Le_Coeur
    I have designed some popup moving menu with JQuery, it looks perfekt in webkit browsers, but i have one problem in mozilla, when i move my popup window, layout of some components in this window changes! For example button add changes from: to: or to: , and it's absolutly random. What can it be? This image is in span: <span class="sw_link_add"></span> .sw_link_add { background:url("/img/confirm_new.png") no-repeat scroll right center transparent; cursor:pointer; padding-right:30px; padding-top:2px; }

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  • Having trouble getting GET variables from url.

    - by mchl
    Hey everyone, I'm having trouble with this algorithm to extract the get variables from a url and print them each on a new line like: x=y z=hello etc. but instead it prints a seemingly random section of the url with no newlines to the file. There must be a logic error of some kind but i just can't spot it. for(i_m=0;i_m<len_m;i_m++) { if(var_m[i_m]=='&') { fwrite(var_m+offset_m, 1, amp_m, echo_out); fputc('\n',echo_out); offset_m+=amp_m; amp_m=0; } amp_m++; } any help appreciated.

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  • Generating a perfectly distributed grid from array

    - by zath
    I'm looking for a formula or rule that will allow me to distribute n characters into a n*n grid with as perfect of a distribution as possible. Let's say we have an array of 5 characters, A through E. Here's an example of how it definitely shouldn't turn out: A B C D E B C D E A C D E A B D E A B C E A B C D The pattern is very clear here, it doesn't look "random". It would look better this way: A B C D E D E A B C B C D E A E A B C D C D E A B What I basically did here was place the A B C D E on the first row, then shift it by 2 on the second row, by 4 on the third row, 1 on the fourth row and 3 on the fifth row. Compared to the very bad example, this one shows no clear pattern. Though I'm certainly hoping there is a pattern, so I can use it to calculate not only small arrays such as this one, but arrays of any size. Any ideas as to how this can be accomplished?

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  • Need help with a sub query/group/order (get latest comment for each ordered topic)

    - by Scarface
    Hey guys I have a query that currently finds the latest comment for each of a user's topics and then orders topics by that comment's timestamp. What I want to do is expand on this query's use and print the latest comment for each topic. The problem with this query is that while it orders the topics correctly, it prints seemingly random comments for each topic. I am trying to implement a sub query but I am not quite sure how to approach it. I was thinking that I just had to somehow use this query to get the comments. If anyone has any ideas I would really appreciate it. Here is what I think I need to add SELECT * FROM comments where topic_id='$topic_id' ORDER BY timestamp DESC LIMIT 1 Here is the query I need to modify SELECT topic.topic_title, topic.content_type, topic.subject_id, topic.creator, topic.description, topic.topic_id,comments.message,comments.user FROM comments JOIN topic ON topic.topic_id = comments.topic_id WHERE topic.creator = '$user' AND comments.timestamp > $week GROUP BY topic_id ORDER BY MAX(comments.timestamp) DESC

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  • strategy to allocate/free lots of small objects

    - by aaa
    hello I am toying with certain caching algorithm, which is challenging somewhat. Basically, it needs to allocate lots of small objects (double arrays, < 256 elements), with objects accessible through mapped value, map[key] = array. time to initialized array may be quite large, generally more than 10 thousand cpu cycles. By lots I mean around gigabyte in total. objects may need to be popped/pushed as needed, generally in random places, one object at a time. lifetime of an object is generally long, minutes or more, however, object may be subject to allocation/deallocation several times during duration of program. What would be good strategy to avoid memory fragmentation, while still maintaining reasonable allocate deallocate speed? I am using C++, so I can use new and malloc. Thanks. I know there a similar questions on website, http://stackoverflow.com/questions/2156745/efficiently-allocating-many-short-lived-small-objects, are somewhat different, thread safety is not immediate issue for me.

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