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  • PHP: MySQL query duplicating update for no reason

    - by ThinkingInBits
    The code below is first the client code, then the class file. For some reason the 'deductTokens()' method is calling twice, thus charging an account double. I've been programming all night, so I may just need a second pair of eyes: if ($action == 'place_order') { if ($_REQUEST['unlimited'] == 200) { $license = 'extended'; } else { $license = 'standard'; } if ($photograph->isValidPhotographSize($photograph_id, $_REQUEST['size_radio'])) { $token_cost = $photograph->getTokenCost($_REQUEST['size_radio'], $_REQUEST['unlimited']); $order = new ImageOrder($_SESSION['user']['id'], $_REQUEST['size_radio'], $license, $token_cost); $order->saveOrder(); $order->deductTokens(); header('location: account.php'); } else { die("Please go back and select a valid photograph size"); } } ######CLASS CODE####### <?php include_once('database_classes.php'); class Order { protected $account_id; protected $cost; protected $license; public function __construct($account_id, $license, $cost) { $this->account_id = $account_id; $this->cost = $cost; $this->license = $license; } } class ImageOrder extends Order { protected $size; public function __construct($account_id, $size, $license, $cost) { $this->size = $size; parent::__construct($account_id, $license, $cost); } public function saveOrder() { //$db = Connect::connect(); //$account_id = $db->real_escape_string($this->account_id); //$size = $db->real_escape_string($this->size); //$license = $db->real_escape_string($this->license); //$cost = $db->real_escape_string($this->cost); } public function deductTokens() { $db = Connect::connect(); $account_id = $db->real_escape_string($this->account_id); $cost = $db->real_escape_string($this->cost); $query = "UPDATE accounts set tokens=tokens-$cost WHERE id=$account_id"; $result = $db->query($query); } } ?> When I die("$query"); directly after the query, it's printing the proper statement, and when I run that query within MySQL it works perfectly.

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  • A*, Tile costs and heuristic; How to approach

    - by Kevin Toet
    I'm doing exercises in tile games and AI to improve my programming. I've written a highly unoptimised pathfinder that does the trick and a simple tile class. The first problem i ran into was that the heuristic was rounded to int's which resulted in very straight paths. Resorting a Euclidian Heuristic seemed to fixed it as opposed to use the Manhattan approach. The 2nd problem I ran into was when i tried added tile costs. I was hoping to use the value's of the flags that i set on the tiles but the value's were too small to make the pathfinder consider them a huge obstacle so i increased their value's but that breaks the flags a certain way and no paths were found anymore. So my questions, before posting the code, are: What am I doing wrong that the Manhatten heuristic isnt working? What ways can I store the tile costs? I was hoping to (ab)use the enum flags for this The path finder isnt considering the chance that no path is available, how do i check this? Any code optimisations are welcome as I'd love to improve my coding. public static List<Tile> FindPath( Tile startTile, Tile endTile, Tile[,] map ) { return FindPath( startTile, endTile, map, TileFlags.WALKABLE ); } public static List<Tile> FindPath( Tile startTile, Tile endTile, Tile[,] map, TileFlags acceptedFlags ) { List<Tile> open = new List<Tile>(); List<Tile> closed = new List<Tile>(); open.Add( startTile ); Tile tileToCheck; do { tileToCheck = open[0]; closed.Add( tileToCheck ); open.Remove( tileToCheck ); for( int i = 0; i < tileToCheck.neighbors.Count; i++ ) { Tile tile = tileToCheck.neighbors[ i ]; //has the node been processed if( !closed.Contains( tile ) && ( tile.flags & acceptedFlags ) != 0 ) { //Not in the open list? if( !open.Contains( tile ) ) { //Set G int G = 10; G += tileToCheck.G; //Set Parent tile.parentX = tileToCheck.x; tile.parentY = tileToCheck.y; tile.G = G; //tile.H = Math.Abs(endTile.x - tile.x ) + Math.Abs( endTile.y - tile.y ) * 10; //TODO omg wtf and other incredible stories tile.H = Vector2.Distance( new Vector2( tile.x, tile.y ), new Vector2(endTile.x, endTile.y) ); tile.Cost = tile.G + tile.H + (int)tile.flags; //Calculate H; Manhattan style open.Add( tile ); } //Update the cost if it is else { int G = 10;//cost of going to non-diagonal tiles G += map[ tile.parentX, tile.parentY ].G; //If this path is shorter (G cost is lower) then change //the parent cell, G cost and F cost. if ( G < tile.G ) //if G cost is less, { tile.parentX = tileToCheck.x; //change the square's parent tile.parentY = tileToCheck.y; tile.G = G;//change the G cost tile.Cost = tile.G + tile.H + (int)tile.flags; // add terrain cost } } } } //Sort costs open = open.OrderBy( o => o.Cost).ToList(); } while( tileToCheck != endTile ); closed.Reverse(); List<Tile> validRoute = new List<Tile>(); Tile currentTile = closed[ 0 ]; validRoute.Add( currentTile ); do { //Look up the parent of the current cell. currentTile = map[ currentTile.parentX, currentTile.parentY ]; currentTile.renderer.material.color = Color.green; //Add tile to list validRoute.Add( currentTile ); } while ( currentTile != startTile ); validRoute.Reverse(); return validRoute; } And my Tile class: [Flags] public enum TileFlags: int { NONE = 0, DIRT = 1, STONE = 2, WATER = 4, BUILDING = 8, //handy WALKABLE = DIRT | STONE | NONE, endofenum } public class Tile : MonoBehaviour { //Tile Properties public int x, y; public TileFlags flags = TileFlags.DIRT; public Transform cachedTransform; //A* properties public int parentX, parentY; public int G; public float Cost; public float H; public List<Tile> neighbors = new List<Tile>(); void Awake() { cachedTransform = transform; } }

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  • Could CouchDB benefit significantly from the use of BERT instead of JSON?

    - by Victor Rodrigues
    I appreciate a lot CouchDB attempt to use universal web formats in everything it does: RESTFUL HTTP methods in every interaction, JSON objects, javascript code to customize database and documents. CouchDB seems to scale pretty well, but the individual cost to make a request usually makes 'relational' people afraid of. Many small business applications should deal with only one machine and that's all. In this case the scalability talk doesn't say too much, we need more performance per request, or people will not use it. BERT (Binary ERlang Term http://bert-rpc.org/ ) has proven to be a faster and lighter format than JSON and it is native for Erlang, the language in which CouchDB is written. Could we benefit from that, using BERT documents instead of JSON ones? I'm not saying just for retrieving in views, but for everything CouchDB does, including syncing. And, as a consequence of it, use Erlang functions instead of javascript ones. This would modify some original CouchDB principles, because today it is very web oriented. Considering I imagine few people would make their database API public and usually its data is accessed by the users through an application, it would be a good deal to have the ability to configure CouchDB for working faster. HTTP+JSON calls could still be handled by CouchDB, considering an extra cost in these cases because of parsing.

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  • What is the benefit to add W3C logo in site?

    - by jitendra
    http://www.w3.org/QA/Tools/Icons If my code is valid then Should i add logo to all my personal and client sites.? Should i add logo to client sites and tell to client these are good to have? If code is valid but semantically correct even can we use logo? What is benefit and purpose to add these logos for XHTML, CSS accessibility. And what is the difference between Gold and Blue logo Why W3C provide these logos?

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  • How and what benefit i can take from included Sizzle.js along with jquery 1.4.2?

    - by metal-gear-solid
    latest jquery 1.4.2 downloaded from jquery.com comes with Sizzle.js also. How and what benefit i can take from included Sizzle.js? /*! * jQuery JavaScript Library v1.4.2 * http://jquery.com/ * * Copyright 2010, John Resig * Dual licensed under the MIT or GPL Version 2 licenses. * http://jquery.org/license * * Includes Sizzle.js * http://sizzlejs.com/ * Copyright 2010, The Dojo Foundation * Released under the MIT, BSD, and GPL Licenses. * * Date: Sat Feb 13 22:33:48 2010 -0500 */

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  • Choosing a low cost wildcard SSL cert (PsotiveSSL, RapidSSL, or other)?

    - by Malcolm
    I'm looking to put in place a wildcard SSL certificate for a server that will be providing REST style web services to multiple subdomains. We use NameCheap.com for our DNS services and they offer a choice of 2 very competitively priced wildcard certs: PositiveSSL Wildcard $129.99/yr RapidSSL Wildcard $148.88/yr Is there any reason to choose one of these branded certs over the other? Or are there problems with these low cost certs that we should aware of? If so, what SSL vendor/products do you recommend and why do you recommend them? Thank you, Malcolm

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  • Is a cluster the most cost effective redundancy method for windows server 2003?

    - by Ryan
    We had a server with bad ram which caused a long outage while they figured it out and our client facing apps had to go down for a while. We are coming up with a solution for instant fail-over but are not sure what the most cost effective method would be. Is a windows server cluster the best method for this? Also note we are using Parallels Virtuozzo if that makes any difference here. We found Parallels has a documented method for setting this up but it said it required a Domain Controller as well as a Fiber connection to shared storage, is all that really needed? Thanks.

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  • How much does SQL Server Web Edition cost? + other related questions

    - by Goma
    Hello. I visited Microsoft pricing page about SQL Server databases, but it was not that clear for me. I want to know the exact cost of SQL Server Web Edition. Furthermore, I would like to know how can I get it if I am with VPS hosting? Should I install it by myself or will they install it for me? And finally, is there a web host that provide SQL Server Web edition so I pay for them directly with the hosting package?

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  • Hosing website on own server. What is Hardware requirement and Cost [closed]

    - by KuKu
    As i am about to finish my dream website, i need to host it on some server. I checked Amazon AWS Free Tier, i found it pretty complex. As i made full website in java(JSP + Servlet + mysql + Node.js), its been expensive to host. So i thought that why not to host on own server so that i will be fully dependent on my resources, not on any one else. And i know, in future i need to pay more and more to the other hosting company(because of uploading images and number of incoming users). So my question is, On initial stage what kind of hardware i will required. What can be the cost of that hardware? I already have 12MBPS broadband connection, will it be sufficient? It has static IP Address as well.

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  • Open Source or Low Cost Layer 7 ("Content") Switch?

    - by Rob
    I have several web servers that host a number of different applications and web sites. I want to make it easy to host apps or parts of web sites on different servers (e.g. example.com/foo might be on one physical server and example.com/bar might be on another). We do this Apache redirects right now, but that gets messy fast and in any case we have other problems we want to solve, such as throttling requests from individual clients, and reducing dependency on specific physical hosts. Is there an open source or low cost layer 7 switch that would be suitable for this sort of task? I was hoping to find something like a stripped down Linux VMware guest/appliance built for this purpose, but haven't seen anything suitable out there so far.

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  • Cost to GC of using weak references in C#?

    - by Scott Bilas
    In another question, Stephen C says: A second concern is that there are runtime overheads with using weak references. The obvious costs are those of creating weak references and calling get on them. A less obvious cost is that significant extra work needs to be done each time the GC runs. So what exactly is the cost to the GC of a weak ref? What extra work does it need to do, and how big of a deal is it? I can make some educated guesses, but am interested in the actual mechanics.

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  • Is the time cost constant when bulk inserting data into an indexed table?

    - by SiLent SoNG
    I have created an archive table which will store data for selecting only. Daily there will be a program to transfer a batch of records into the archive table. There are several columns which are indexed; while others are not. I am concerned with time cost per batch insertion: - 1st batch insertion: N1 - 2nd batch insertion: N2 - 3rd batch insertion: N3 The question is: will N1, N2, and N3 roughly be the same, or N3 N2 N1? That is, will the time cost be a constant or incremental, with existence of several indexes? All indexes are non-clustered. The archive table structure is this: create table document ( doc_id int unsigned primary key, owner_id int, -- indexed title smalltext, country char(2), year year(4), time datetime, key ix_owner(owner_id) }

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  • Single click handler for all buttons in Javascript? Is it a pattern? Whats the benefit?

    - by Hasan Khan
    I have been told that when there are multiple buttons on the page for same purpose but targeting different item e.g. delete item on a grid of items, they say it is recommended to just register for click handler only on the top most element like 'body' and check what was clicked instead of hooking up click with every delete button. Whats the benefit of this? Creating more handlers causes problems? Is it an optimization of some sort? Is it a pattern? Does it have anything to do with performance? Where can I read more about it?

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  • What can I do to lower bandwidth cost on a bandwidth heavy site?

    - by acidzombie24
    The easiest answer is CDN but I'd like to ask. A friend of mine has a server that is used for mirror downloads. He says he is doing about 10TB of bandwidth a month which shocked me (I wonder if he is lying). I seen his site and he has no ads. I suspect he might close his website once he gets the bill. Anyways I was wondering since his CPU/RAM is not being used and his HD usage is around 15gb what he can do to lower cost if he continues this site. I said put up ads but I don't know if ads would cover it I found one CDN which offers $0.070 / GB. 10240gb (10TB) * .07 = $717 a month. That seems a little steep but he is using lots of traffic due to it being a mirror site. Also using a CDN doesnt make sense as he doesn't need multiple servers hosting the files in different areas (which is one reason he isn't using that now). He just needs a big upload pipe Is there something he can do? At the moment he is paying $200 a month on a dedicated server and he is using WAY more bandwidth then he should be using. Side question: Can gz-ing files large already compressed files help? like on (zip, rars, etc)

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  • how to call sql string from nhibernate

    - by frosty
    i have the following method, at the moment it's return the whole sql string. How would i execute the following. using (ITransaction transaction = session.BeginTransaction()) { string sql = string.Format( @"DECLARE @Cost money SET @Cost = -1 select @Cost = MAX(Cost) from item_costings where Item_ID = {0} and {1} >= Qty1 and {1} <= Qty2 RETURN (@Cost)", itemId, quantity); string mystring = session .CreateSQLQuery(sql) .ToString(); transaction.Commit(); return mystring; } // EDIT here is the final version using criteria using (ISession session = NHibernateHelper.OpenSession()) { decimal cost = session .CreateCriteria(typeof (ItemCosting)) .SetProjection(Projections.Max("Cost")) .Add(Restrictions.Eq("ItemId", itemId)) .Add(Restrictions.Le("Qty1", quantity)) .Add(Restrictions.Ge("Qty2", quantity)) .UniqueResult<decimal>(); return cost; }

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  • How to find minimum weight with maximum cost in 0-1 Knapsack algorithm?

    - by Nitin9791
    I am trying to solve a spoj problem Party Schedule the problem statement is- You just received another bill which you cannot pay because you lack the money. Unfortunately, this is not the first time to happen, and now you decide to investigate the cause of your constant monetary shortness. The reason is quite obvious: the lion's share of your money routinely disappears at the entrance of party localities. You make up your mind to solve the problem where it arises, namely at the parties themselves. You introduce a limit for your party budget and try to have the most possible fun with regard to this limit. You inquire beforehand about the entrance fee to each party and estimate how much fun you might have there. The list is readily compiled, but how do you actually pick the parties that give you the most fun and do not exceed your budget? Write a program which finds this optimal set of parties that offer the most fun. Keep in mind that your budget need not necessarily be reached exactly. Achieve the highest possible fun level, and do not spend more money than is absolutely necessary. Input The first line of the input specifies your party budget and the number n of parties. The following n lines contain two numbers each. The first number indicates the entrance fee of each party. Parties cost between 5 and 25 francs. The second number indicates the amount of fun of each party, given as an integer number ranging from 0 to 10. The budget will not exceed 500 and there will be at most 100 parties. All numbers are separated by a single space. There are many test cases. Input ends with 0 0. Output For each test case your program must output the sum of the entrance fees and the sum of all fun values of an optimal solution. Both numbers must be separated by a single space. Example Sample input: 50 10 12 3 15 8 16 9 16 6 10 2 21 9 18 4 12 4 17 8 18 9 50 10 13 8 19 10 16 8 12 9 10 2 12 8 13 5 15 5 11 7 16 2 0 0 Sample output: 49 26 48 32 now I know that it is an advance version of 0/1 knapsack problem where along with maximum cost we also have to find minimum weight that is less than a a given weight and have maximum cost. so I have used dp to solve this problem but still get a wrong awnser on submission while it is perfectly fine with given test cases. My code is typedef vector<int> vi; #define pb push_back #define FOR(i,n) for(int i=0;i<n;i++) int main() { //freopen("input.txt","r",stdin); while(1) { int W,n; cin>>W>>n; if(W==0 && n==0) break; int K[n+1][W+1]; vi val,wt; FOR(i,n) { int x,y; cin>>x>>y; wt.pb(x); val.pb(y); } FOR(i,n+1) { FOR(w,W+1) { if(i==0 || w==0) { K[i][w]=0; } else if (wt[i-1] <= w) { if(val[i-1] + K[i-1][w-wt[i-1]]>=K[i-1][w]) { K[i][w]=val[i-1] + K[i-1][w-wt[i-1]]; } else { K[i][w]=K[i-1][w]; } } else { K[i][w] = K[i-1][w]; } } } int a1=K[n][W],a2; for(int j=0;j<W;j++) { if(K[n][j]==a1) { a2=j; break; } } cout<<a2<<" "<<a1<<"\n"; } return 0; } Could anyone suggest what am I missing??

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  • What is the possible benefit (if any) of allowing recursive contructors?

    - by Penang
    In Java, constructors cannot be recursive. Compile time error: "recursive constructor invocation". Let's assume that we did not have this restriction. Things to keep in mind: The return type of a constructor is void. Since it is a void method you can't harness the complete power of recursion. A constructor can invoke itself (or any other constructor) using this(). But a "call to this must be first statement in constructor" We could use non local data between consecutive calls to still have some possible gain from recursive constructors. Would there be any benefit from allowing recursive constructors?

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  • What's the benefit of calling new on an object instance?

    - by Geo
    I'm reading [Programming Perl][1], and I found this code snippet: sub new { my $invocant = shift; my $class = ref($invocant) || $invocant; my $self = { color => "bay", legs => 4, owner => undef, @_, # Override previous attributes }; return bless $self, $class; } With constructors like this one, what's the benefit of calling new on an object instance? I assume that it's what it's for, right? My guess is that if anyone would want to write such a constructor, he would have to add some more code that copies the attributes of the first object to the one about to be created.

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  • What is the benefit to wrapping every sql/stored proc invocation in a transaction?

    - by MatthewMartin
    The following code executes one stored procedure. The stored procedure has only one command in it. Is there any benefit to wrapping everything in a transaction, even it only has one SQL statement in it (or one stored proc that has only one sql statement)? In the sample code below, if the delete fails, it fails. There is nothing else to be rolled back (it seems). So why is everything wrapped in a transaction anyhow? using (ITransactionManager transMan = repository.TransactionManager()) using (IController controller = repository.Controller()) { transMan.BeginTransaction(); try { //DELETE FROM myTable where Id=@id controller.Delete(id); transMan.CommitTransaction(); } catch { transMan.RollbackTransaction(); throw; } }

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  • Learning Python Basics

    - by StaticExtasy
    So I'm trying to learn python better and i've been using this website http://www.learnpython.org/ I'm on to functions right now, heres the code #Add your functions here (before the existing functions) def list_benefits(): myList = ['More organized code','More readable code','Easier code reuse','Allowing programmers to share and connect code together'] return myList def build_sentence(info): addMe = " is a benefit of functions!" for i in info: meInfo = i + addMe return meInfo def name_the_benefits_of_functions(): list_of_benefits = list_benefits() for benefit in list_of_benefits: print build_sentence(benefit) name_the_benefits_of_functions() the output being e is a benefit of functions! e is a benefit of functions! e is a benefit of functions! r is a benefit of functions! What am i missing to return the whole scentence

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  • How much did it cost our competitor to DDoS us at 50 Gbps for two weeks?

    - by MiniQuark
    I know that this question may sound like an invalid serverfault question, but I believe that it's quite valid: the amount of time and effort that a sysadmin should spend on DDoS protection is a direct function of typical DDoS prices. Let me rephrase this: protecting a web site against small attacks is one thing, but resisting 50 Gbps of UDP flood is another and requires time & money. Deciding whether or not to spend that time & money depends on whether such an attack is likely or not, and this in turn depends on how cheap and simple such an attack is for the attacker. So here's the full story: our company has been victim to a massive DDoS attack (over 50 Gbps of UDP traffic, full-time during 2 weeks). We are pretty sure that it's one of our competitors, and we actually know which one, because we were the only two remaining competitors on a very big request for proposal, and the DDoS attack magically stopped the day we won (double hurray, by the way)! These people have proved in the past that they are very dishonest, but we know that they are not technical at all, so we believe that they simply paid for some botnet DDoS service. I would like to know how much these services typically cost, for such a large scale attack. Please do not give any link to such services, I would really hate to give these people any publicity. I understand that a hacker could very well do this for free, but what's a typical price for such an attack if our competitors paid for it through some kind of botnet service? It is really starting to scare me (if we're talking thousands of dollars here, then I am really going to freak off: who knows, they might just hire a hit-man one day?). Of course we filed a complaint, but the police says that they cannot do much about it (DDoS attacks are virtually untraceable, so they say), and our suspicions are not enough to justify them raiding our competitor's offices to search for proofs. For your information, we now changed our infrastructure to be able to sustain such attacks: we now use a major CDN service so that our servers are not directly affected by DDoS attacks. Requests for dynamic pages do get proxied to our servers, but for low level attacks (UDP flood, or Syn floods, for example) we only receive legitimate trafic, so we're fine. If they decide to launch higher level attacks (HTTP flood or slowloris attacks for example), most of the load should be handled by the CDN... at least I hope so! Thank you very much for your help.

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