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• C++ struct containing unsigned char and int bug

  - by powerfear

  Ok i have a struct in my C++ program that is like this: struct thestruct { unsigned char var1; unsigned char var2; unsigned char var3[2]; unsigned char var4; unsigned char var5[8]; int var6; unsigned char var7[4]; }; When i use this struct, 3 random bytes get added before the "var6", if i delete "var5" it's still before "var6" so i know it's always before the "var6". But if i remove the "var6" then the 3 extra bytes are gone. If i only use a struct with a int in it, there is no extra bytes. So there seem to be a conflict between the unsigned char and the int, how can i fix that?

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• Is there "good" PRNG generating values without hidden state?

  - by actual

  I need some good pseudo random number generator that can be computed like a pure function from its previous output without any state hiding. Under "good" I mean: I must be able to parametrize generator in such way that running it for 2^n iterations with any parameters should cover all or almost all values between 0 and 2^n - 1, where n is the number of bits in output value. Combined generator output of n + p bits must cover all or almost all values between 0 and 2^(n + p) - 1 if I run it for 2^n iterations for every possible combination of its parameters, where p is the number of bits in parameters. For example, LCG can be computed like a pure function and it can meet first condition, but it can not meet second one. Say, we have 32-bit generator, m = 2^32 and it is constant, our p = 64 (two 32-bit parameters a and c), n + p = 96, so we must peek data by three ints from output to meet second condition. Unfortunately, condition can not be meet because of strictly alternating sequence of odd and even ints in output. To overcome this, hidden state must be introduced, but that makes function not pure and breaks first condition (period become much longer). Am I wanting too much?

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• Color blindness: Are you aware of it? Do you design for it?

  - by User

  I'm curious whether many of us who do design or take design decisions have ever heard of this problem. I'm aware there are dangerous color combinations, like green + red. This is probably one of the most popular cases of color blindness. If you have green text on a red background and vice versa some people won't see anything. I've also seen in practice that green text on a blue background was not seen by one guy. What other color compositions should be avoided, and how often these cases are to be expected? Let us make some ranging by encounter probability who has the numbers. Addition: I've just remembered one very bad example that causes problems to just about everyone - blue text on a black background. It's unreadable for all intents and purposes. Never could understand what could possibly compel a web master to use this color combination...

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• Trouble with arraylist and stack

  - by helloman

  I am having trouble starting out this program, I am suppose to write a program that will create an ArrayList, asking the user for 10 numbers. Then this will be put into the Array. Then after the list is made navigate it and if a number is even remove it from the ArrayList and copy it to a stack of integers. import java.io.* ; import java.util.*; public class Test { public static void main(String[] args){ Scanner input = new Scanner (System.in); ArrayList<Integer> integers = new ArrayList<Integer>(); System.out.print ("Enter Number: \n"); for (int i = 0; i < 10; i++){ integers.add(input.nextInt()); } for (int i = 0; i < 10 ; i++){ if (i %2==0) } } }

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• Background thread in C#

  - by Xodarap

  When the user saves some data, I want to spin off a background thread to update my indexes and do some other random stuff. Even if there is an error in this indexing the user can't do anything about it, so there is no point in forcing the main thread to wait until the background thread finishes. I'm doing this from a ASP.NET process, so I think I should be able to do this (as the main thread exiting won't kill the process). When I set a breakpoint in the background thread's method though, the main thread also appears to stop. Is this just an artifact of visual studio's debugger, or is the main thread really not going to return until the background thread stops?

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• speed up calling lot of entities, and getting unique values, google app engine python

  - by user291071

  OK this is a 2 part question, I've seen and searched for several methods to get a list of unique values for a class and haven't been practically happy with any method so far. So anyone have a simple example code of getting unique values for instance for this code. Here is my super slow example. class LinkRating2(db.Model): user = db.StringProperty() link = db.StringProperty() rating2 = db.FloatProperty() def uniqueLinkGet(tabl): start = time.time() dic = {} query = tabl.all() for obj in query: dic[obj.link]=1 end = time.time() print end-start return dic My second question is calling for instance an iterator instead of fetch slower? Is there a faster method to do this code below? Especially if the number of elements called be larger than 1000? query = LinkRating2.all() link1 = 'some random string' a = query.filter('link = ', link1) adic ={} for itema in a: adic[itema.user]=itema.rating2

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• How can I sync three classes?

  - by TheMachineCharmer

  class Foo { Bar b; List<Foo> Neighbours; } class Bar { Spam s; List<Bar> Neighbours; } class Spam { List<string> Neighbours; } Each of these classes have AddNeighbour,RemoveNeighbour methods. User can add/remove Neighbours from any of the class at random. I want these three objects to be in sync. How can I do this?

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• Display constantly updating information in-place in command-line window using python?

  - by AndyL

  I am essentially building a timer. I have a python script that monitors for an event and then prints out the seconds that have elapsed since that event. Instead of an ugly stream of numbers printed to the command line, I would like to display only the current elapsed time "in-place"-- so that only one number is visible at any given time. Is there a simple way to do this? If possible I'd like to use built-in python modules. I'm on Windows, so simpler the better. (E.g. no X11).

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• To not iterate through function of Array object if it is added to Array prototype

  - by Rishat Muhametshin

  According to the way to add indexOf method to Array class in IE6, how do I now reject this method from iterating through any random array? For example: Array.prototype.indexOf = function(needle) { ... }; var array = [1, 2, 3]; for (var i in array) { document.write(i + ': ' + array[i]); } gives output 0: 1 1: 2 2: 3 indexOf: function ... How can I skip indexOf property and stop iterating on it without adding any code to where for(...) is called?

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• Diff/Merge functionality for objects (not files!)

  - by gehho

  I have a collection of objects of the same type, let's call it DataItem. The user can view and edit these items in an editor. It should also be possible to compare and merge different items, i.e. some sort of diff/merge for DataItem instances. The DIFF functionality should compare all (relevant) properties/fields of the items and detect possible differences. The MERGE functionality should then be able to merge two instances by applying selected differences to one of the items. For example (pseudo objects): DataItem1 { DataItem2 { Prop1 = 10 Prop1 = 10 Prop2 = 25 Prop2 = 13 Prop3 = 0 Prop3 = 5 Coll = { 7, 4, 8 } Coll = { 7, 4, 8, 12 } } } Now, the user should be provided with a list of differences (i.e. Prop2, Prop3, and Coll) and he should be able to select which differences he wants to eliminate by assigning the value from one item to the other. He should also be able to choose if he wants to assign the value from DataItem1 to DataItem2 or vice versa. Are there common practices which should be used to implement this functionality? Since the same editor should also provide undo/redo functionality (using the Command pattern), I was thinking about reusing the ICommand implementations because both scenarios basically handle with property assignments, collection changes, and so on... My idea was to create Difference objects with ICommand properties which can be used to perform a merge operation for this specific Difference. Btw: The programming language will be C# with .NET 3.5SP1/4.0. However, I think this is more of a language-independent question. Any design pattern/idea/whatsoever is welcome!

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• 0/1 Knapsack with irrational weights

  - by user356106

  Consider the 0/1 knapsack problem. The standard Dynamic Programming algorithm applies only when the capacity as well as the weights to fill the knapsack with are integers/ rational numbers. What do you do when the capacity/weights are irrational? The issue is that we can't memoize like we do for integer weights because we may need potentially infinite decimal places for irrational weights - leading to an infinitely large number of columns for the Dynamic Programming Table . Is there any standard method for solving this? Any comments on the complexity of this problem? Any heuristics? What about associated recurrences like (for example): f(x)=1, for x< sqrt(2) f(x)=f(x-sqrt(2))+sqrt(3)

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• How to read a file line using php in a javascript variable without the breakline character ?

  - by coolboycsaba

  I have a txt file on the server which contains 10 lines of text. The text file is rewritten sometimes, and I get new lines using "\r\n". My problem shows when I want to load the lines in javascript variables. I do it like this, but this work only for numbers or for the last line of the file, because its not using the breakline tag: var x = '<?php echo $file[0]; ?>'; Ive tried to alert(x) but it`s not working.... (working only if I read the last line) Any idead ?

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• pyschool is wrong ?

  - by geekkid

  I'm currently learning python and trying to do exercises at pyschools (if anyone knows what it is). Anyway, i have an exercise that asks me to do the following : Write a function percent(value, total) that takes in two numbers as arguments, and returns the percentage value as an integer. Here's my code: def percent(value, total): percent = value / total * 100 return int(percent) It works great in my Python Idle and it gives all the correct answers. however, when i run it in the pyschools website, it says that , for example , when the function is called with parameters 46 and 90 , the function returns 0. However, in my python idle , it correctly returns 51. What might be the problem ? Thank you very much for your help!

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• Simple Serialization Faster Than JSON? (in Ruby)

  - by Sinan Taifour

  I have an application written in ruby (that runs in the JRuby VM). When profiling it, I realized that it spends a lot (actually almost all of) its time converting some hashes into JSON. These hashes have keys of symbols, values of other similar hashes, arrays, strings, and numbers. Is there a serialization method that is suitable for such an input, and would typically run faster than JSON? It would preferable if it is has a Java or JRuby-compatible gem, too. I am currently using the jruby-json gem, which is the fastest JSON implementation in JRuby (as I am told), so the move will most likely be to a different serialization method rather than just a different library. Any help is appreciated! Thanks.

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• IPhone: different system timers??

  - by matt

  I have been using mach_absolute_time() for all my timing functions so far. calculating how long between frames ect. I now want to get the exact time touch input events happen using event.timestamp in the touch callbacks. the problem is these two seem to use completely different timers. sure, you can get them both in seconds, but their origins are different and seemingly random... is there any way to sync the two different timers? or is there anyway to get access to the same timer that the touch input uses to generate that timestamp property? otherwise its next to useless.

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• How to profile object creation in Java?

  - by gooli

  The system I work with is creating a whole lot of objects and garbage collecting them all the time which results in a very steeply jagged graph of heap consumption. I would like to know which objects are being generated to tune the code, but I can't figure out a way to dump the heap at the moment the garbage collection starts. When I tried to initiate dumpHeap via JConsole manually at random times, I always got results after GC finished its run, and didn't get any useful data. Any notes on how to track down excessive temporary object creation are welcome.

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• Which method of adding items to the ASP.NET Dictionary class is more efficient?

  - by ahmd0

  I'm converting a comma separated list of strings into a dictionary using C# in ASP.NET (by omitting any duplicates): string str = "1,2, 4, 2, 4, item 3,item2, item 3"; //Just a random string for the sake of this example and I was wondering which method is more efficient? 1 - Using try/catch block: Dictionary<string, string> dic = new Dictionary<string, string>(); string[] strs = str.Split(','); foreach (string s in strs) { if (!string.IsNullOrWhiteSpace(s)) { try { string s2 = s.Trim(); dic.Add(s2, s2); } catch { } } } 2 - Or using ContainsKey() method: string[] strs = str.Split(','); foreach (string s in strs) { if (!string.IsNullOrWhiteSpace(s)) { string s2 = s.Trim(); if (!dic.ContainsKey(s2)) dic.Add(s2, s2); } }

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• Haskell - mapping the odd placed values and the even placed values differently

  - by Abstract

  Hey guys, is there an easy way. To take a list of numbers, say 123456. Then multiply the odd placed by three and the even placed by 1. i.e. (1 * 3) + (2 * 1) + (3 * 3) + (4*1) + (5*3) + (6*1) i was thinking the map function somewhere along the lines. But i don't know how to map *3 to just the odd placed values. Oh and if you could give me the version not in prelude that would be great like the actual function or functions, as if its being imported from an external haskell file Thanks for the help

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• number with sign in combobox dataprovider

  - by gauravgr8

  Hi, I am trying to display country codes(+91, +60, +01) in the combobox. Although the dataprovider(array) contains + sign but is removed. I am not getting how to show it with sign. <mx:Array id="countryArray"> <mx:Object label="India" data="+91" /> <mx:Object label="Malaysia" data="+60" /> <mx:Object label="Usa" data="+01" /> </mx:Array> Is this the problem with dataprovider? How can I treate them as text not numbers? Please help. Thanks in advance.

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• Uncommitted reads in SSIS

  - by OldBoy

  I'm trying to debug some legacy Integration Services code, and really want some confirmation on what I think the problem is: We have a very large data task inside a control flow container. This control flow container is set up with TransactionOption = supported - i.e. it will 'inherit' transactions from parent containers, but none are set up here. Inside the data flow there is a call to a stored proc that writes to a table with pseudo code something like: "If a record doesn't exist that matches these parameters then write it" Now, the issue is that there are three records being passed into this proc all with the same parameters, so logically the first record doesn't find a match and a record is created. The second record (with the same parameters) also doesn't find a match and another record is created. My understanding is that the first 'record' passed to the proc in the dataflow is uncommitted and therefore can't be 'read' by the second call. The upshot being that all three records create a row, when logically only the first should. In this scenario am I right in thinking that it is the uncommitted transaction that stops the second call from seeing the first? Even setting the isolation level on the container doesn't help because it's not being wrapped in a transaction anyway.... Hope that makes sense, and any advice gratefully received. Work-arounds confer god-like status on you.

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• How efficient is an if statement compared to a test that doesn't use an if? (C++)

  - by Keand64

  I need a program to get the smaller of two numbers, and I'm wondering if using a standard "if x is less than y" int a, b, low; if (a < b) low = a; else low = a; is more or less efficient than this: int a, b, low; low = b + ((a - b) & ((a - b) >> 31)); (or the variation of putting int delta = a - b at the top and rerplacing instances of a - b with that). I'm just wondering which one of these would be more efficient (or if the difference is to miniscule to be relevant), and the efficiency of if-else statements versus alternatives in general.

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• Diff multiple files in perforce across a revision range

  - by Thanatos

  I'd like to diff a bunch of lines across several revisions. Like, I'd like to see a.c, b.c, and c.c from changelist X to changelist Y. p4 diff2 a.c@X a.c@Y (where X & Y are changelist numbers) seems to work, but only sometimes. Specifically, if a.c is non-existent at X, I don't get a diff. I'd like to be able to get the diff (even though it'll be the whole file with only adds) anyways. To get the bigger picture: I have several files, across several commits, and I'd like to merge the diffs of these files in these commits, to basically say "this is a diff of what changed in this set of files during this set of changelists"

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• How to get Field Labels from PIMItem - Blackberry

  - by Taha

  How can we get Field Labels from PIMItem. The following code is with PIMList String label = pimList.getAttributeLabel(blackBerryContact.getAttributes(Contact.TEL, i)); But i have PIMItem. There is a method PIMItem.getPIMList() which returns null for me in the code below. THE API at http://www.blackberry.com/developers/docs/5.0.0api/index.html says "getPIMList() Gets the PIMList associated with this item." Below is sample code that i am trying to achive - // Load the address Book and allow the user to select a contact BlackBerryContactList contactList = (BlackBerryContactList) PIM.getInstance().openPIMList(PIM.CONTACT_LIST,PIM.READ_ONLY); PIMItem userSelectedContact = contactList.choose(); // Now get the Field labels for contact numbers for userSelectedContact

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• Eclipse organization: workspaces, working sets, projects, folders, multiple source folders, ....!!!

  - by Ricket

  There is quite a tier of organization in Eclipse. You can have multiple workspaces, each of which can have projects, these projects can be assigned to working sets, and then each project can have source folders... How do you use all this organization? Do you even use it all? Working sets are so hidden that I hardly know what they are; are they commonly used, or are they hidden because they are so uncommonly used? What is even the methodology behind all this? I'd like a good explanation of the recommended way to use all these different organizational layers, because at the moment I basically just have a bunch of random projects in a single workspace (the default %USER%/workspace folder) and it's getting to be quite an alphabetical mess. So in essence: How do you keep your Eclipse workspace(s) organized?

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• Sending out 20,000+ emails with asp.net

  - by Kyle

  I am writing an application that will need to send a massive amount of emails to our students who will be selected from our database (each email will be personalized to the extent that will include their name, course of study etc...so needs to be sent one at a time). I could do this looping over an SmtpClient, but I'm afraid that with the numbers I'm trying to send, I'll ultimately run into timeout issues or my thread being killed because of lack of machine resources. At this point I'm just looking for suggestions of a better way to handle this, or if looping over SmtpClient is an ok solution, how I should go about handling it to prevent what I posted above. Would a web service be a better alternative? Please advise, TIA

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