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  • Array Indexing Properties of A Class

    - by Chris
    I have a class that has several properties: class Person { string Name; int Age; DateTime BirthDate; } Then I have a sort of wrapper class with a List<Person>. Within this wrapper class I want to be able to do something like Wrapper["Name"] that returns a new List<string> using .Select(x=>x.Name). How do I create a wrapper class around an IEnumerable that supports mapping a string to the Property name? Something like the pseudo code below, but obviously it doesn't work. I'm 99.9% sure the solution will have to use Reflection and thats fine. class Wrapper { List<Person> PersonList; List<dynamic> this[string Column] { return PersonList.Select(x => x.[Column]).ToList(); } } This may not seem like a good design, but its a fix to eventually enable the correct design from .NET 2.0 days. As I have it right now, the data is stored in Columns, so there is actually a List of Lists within my class right now. Using the above example there would be three ILists (with a string Title) Name, Age, and Birthdate. Everything is currently predicated on addressing the columns by their "string" name. I'm trying to convert the data structure to row based with an IEnumberable interface to allow Linq eventually while still maintaining the functionality of my current code. Is converting the code to a Row based IEnumberable a good idea?

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  • How to start coding the "Dining Philosophers" simulation?

    - by GrizzlyGuru
    I'm not a beginner at C# but I really need to increase my understanding, so I've picked a classic deadlock problem to code to help teach myself some of the more advanced concepts of C#. The Dining Philosophers Problem seems like a good one, but I need a little help to get started. I know I need to approach the "diners" as objects, but to simulate the random delays between eating, should I look to threading with each diner in a separate thread? Do I need some kind of "master" to monitor all the actions? Any general design concept advice is welcome, but I'd like to do the grunt programming as an exercise. Thanks!

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  • Using pow() for large number

    - by g4ur4v
    I am trying to solve a problem, a part of which requires me to calculate (2^n)%1000000007 , where n<=10^9. But my following code gives me output "0" even for input like n=99. Is there anyway other than having a loop which multilplies the output by 2 every time and finding the modulo every time (this is not I am looking for as this will be very slow for large numbers). #include<stdio.h> #include<math.h> #include<iostream> using namespace std; int main() { unsigned long long gaps,total; while(1) { cin>>gaps; total=(unsigned long long)powf(2,gaps)%1000000007; cout<<total<<endl; } }

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  • Creating objects makes the VM faster?

    - by Sudhir Jonathan
    Look at this piece of code: MessageParser parser = new MessageParser(); for (int i = 0; i < 10000; i++) { parser.parse(plainMessage, user); } For some reason, it runs SLOWER (by about 100ms) than for (int i = 0; i < 10000; i++) { MessageParser parser = new MessageParser(); parser.parse(plainMessage, user); } Any ideas why? The tests were repeated a lot of times, so it wasn't just random. How could creating an object 10000 times be faster than creating it once?

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  • In SQL How do I copy values from one table to another based on another field's value?

    - by Joshua1729
    Okay I have two tables VOUCHERT with the following fields ACTIVATIONCODE SERIALNUMBER VOUCHERDATADBID UNAVAILABLEAT UNAVAILABLEOPERATORDBID AVAILABLEAT AVAILABLEOPERATORDBID ACTIVATIONCODENEW EXT1 EXT2 EXT3 DENOMINATION -- I added this column into the table. and the second table is VOUCHERDATAT with the following fields VOUCHERDATADBID BATCHID VALUE CURRENCY VOUCHERGROUP EXPIRYDATE AGENT EXT1 EXT2 EXT3 What I want to do is copy the corresponding VALUE from VOUCHERDATAT and put it into DENOMINATION of VOUCHERT. The linking between the two is VOUCHERDATADBID. How do I go about it? It is not a 1:1 mapping. What I mean is there may be 1000 SERIALNUMBERS with a same VOUCHERDATADBID. And that VOUCHERDATADBID has only entry in VOUCHERDATAT, hence one value. Therefore, all serial numbers belonging to a certain VOUCHERDATADBID will have the same value. Will JOINS work? What type of JOIN should I use? Or is UPDATE table the way to go? Thanks for the help !!

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  • How to change Hibernate´s auto persistance strategy

    - by Kristofer Borgstrom
    I just noted that my hibernate entities are automatically persisted to the database (or at least to cache) before I call any save() or update() method. To me this is a pretty strange default behavior but ok, as long as I can disable it, it´s fine. The problem I have is I want to update my entity´s state (from 1 to 2) only if the entity in the database still has the state it had when I retrieved [1] (this is to eliminate concurrency issues when another server is updating this same object). For this reason I have created a custom NamedQuery that will only update the entity if state is 1. So here is some pseudo-code: //Get the entity Entity item = dao.getEntity(); item.getState(); //==1 //Update the entity item.setState(2); //Here is the problem, this effectively changes the state of my entity braking my query that verifies that state is still == 1. dao.customUpdate(item); //Returns 0 rows changes since state != 1. So, how do I make sure the setters don´t change the state in cache/db? Thanks, Kristofer

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  • What to do with twitter oauth token once retreived?

    - by mcintyre321
    I'm writing a web app that will use twitter as its primary log on method. I've written code which gets the oauth token back from Twitter. My plan is now to Find the entry in my Users table for the twitter username retreived using the token, or create the entry if necessary Update the Users.TwitterOAuthToken column with the new OAuth token Create a permanent cookie with a random guid on the site and insert a record into my UserCookies table matching Cookie to User when a request comes in I will look for the browser cookie id in the UserCookies table, then use that to figure out the user, and make twitter requests on their behalf Write the oauth token into some pages as a js variable so that javascript can make requests on behalf of the user If the user clears his/her cookies the user will have to log in again to twitter Is this the correct process? Have I created any massive security holes? thanks!

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  • iPhone OS Memory Warnings. What Do The Different Levels Mean?

    - by dugla
    Regarding the black art of managing memory on iPhone OS devices: what do the different levels of memory warning mean. Level 1? Level 2? Does the dial go to 11? Context: After an extensive memory stress testing period - including running my iPad app with the iPod music player app playing, I am inclined to ignore the random yet infrequent memory warnings I am receiving. My app never crashes. Ever. My app is leak free. And, well, the mems warnings just don't seem to matter. Thanks, Doug

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  • Texture repeats even with GL_CLAMP_TO_EDGE set [FIXED]

    - by Lliane
    Hi, i'm trying to put a translucing texture on a face which uses points 1 to 4 (don't mind the numbers) on the following screenshot Sadly as you can see the texture repeats herself in both dimensions, I tried to switch the TEXTURE_WRAP_S from REPEAT to CLAMP_to_EDGE but it doesn't change anything. Texture loading code is here : gl.glBindTexture(gl.GL_TEXTURE_2D, mTexture.get(4)); gl.glActiveTexture(4); gl.glTexParameterf(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR); gl.glTexParameterf(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE); gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, shadowbmp.width, shadowbmp.height, 0, gl.GL_RGBA, gl.GL_UNSIGNED_SHORT_4_4_4_4, shadowbmp.buffer); Texture coordinates are the following : float shadow_bot_text[] = { 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f }; Thanks

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  • Pagination using Ajax in jquery Datatables

    - by kshtjsnghl
    I am using dataTables plugin for a table on a page I am working on. Its basically fetching rows through an ajax call and in this ajax call, I send the search params that the user selects and the page number required. I need the Next, Previous, First and Last buttons to also fire the same ajax call, but with different page numbers, as the back-end interceptor depends on the page number. This api call would return total no. of rows(say 1000) belonging for these search params and the rows with the page size( say 50). Is there any way, I can use data table to do this?

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  • Trouble converting string/character to byte in lisp

    - by WanderingPhd
    I've some data that I'm reading in using read-line and I want to convert it into a byte-array. babel:string-to-octet works for the most part except when the character\byte is larger (above 200) in which case it returns two numbers. As an example, if the character is ú using babel:string-to-octet returns (195 185) instead of 250 which is what I'm looking for. I tried a number of encodings in babel but none of them seem to work. If I use read-byte or read-sequence it does read in 250. But for reasons of backward compatibility, I'm left with using read-line and I would like to know if there is something I'm missing when using babel:string-to-octet to convert ú to 250. I'm using ccl 1.8 btw.

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  • Characters with jquery json

    - by Mikk
    Hi everyone, I'm using jquery $.getJSON to retrieve list of cities. Everything works fine, but I'm from Estonia (probably most of you don't know much about this country =D) and we are using some characters like õ, ü. ä, ö. When I pass letters like this to callback function, I keep getting empty strings. I've tried to base64 encode(server-side)-decode(jquery base64 plugin) strings (i thought it was a good idea as long as I can compress pages with php, so I don't have to worry about bandwidth), but in this way I end up with some random chinese symbols. What would be the best workaround for this problem. Thank you.

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  • How can I check with a regex that a string contains only certain allowed characters?

    - by Camran
    I need a special regular expression, have no experience in them whatsoever so I am turning to you guys on this one: I need to validate a classifieds title field so it doesn't have any special characters in it, almost. Only letters and numbers should be allowed, and also the swedish three letters å, ä, ö, and also not case sensitive. Besides the above, these should also be allowed: The "&" sign. Parenthesis sign "()" Mathematical signs "-", "+", "%", "/", "*" Dollar and Euro signs One accent signed letter: "é". //Only this one is required Double quote and singel quote signs. The comma "," and point "." signs Thanks

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  • += Overloading in C++ problem.

    - by user69514
    I am trying to overload the += operator for my rational number class, but I don't believe that it's working because I always end up with the same result: RationalNumber RationalNumber::operator+=(const RationalNumber &rhs){ int den = denominator * rhs.denominator; int a = numerator * rhs.denominator; int b = rhs.numerator * denominator; int num = a+b; RationalNumber ratNum(num, den); return ratNum; } Inside main //create two rational numbers RationalNumber a(1, 3); a.print(); RationalNumber b(6, 7); b.print(); //test += operator a+=(b); a.print(); After calling a+=(b), a is still 1/3, it should be 25/21. Any ideas what I am doing wrong?

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  • Solr adding document cycle & wait on response issue

    - by user1585896
    I am trying to send http post request to Solr for adding 50000 documents (all individual request one after another in while loop). I am using DefaultHttpClient in java to connect to Solr and when I use execute method on my HttpPost Solr takes 3 to 4 ms to response. I have commit=false, autoCommit=false, autoSoftCommit=false. My question is why it takes that much time to response and why cycle it follows to add new document. Basically I want to send add request but do not want to commit to see how many request can Solr handle without doing any kind of commits(without having to do any disk access). My guess is with above parameter tuned off I should be hitting Solr about 10000 times every second, but my result is 300 times a second. I am generating random data to add in my code.

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  • Declaring an integer Range with step != 1 in Ruby

    - by Dan Tao
    Hey guys, I'm completely new to Ruby, so be gentle. Say I want to iterate over the range of even numbers from 2 to 100; how would I do that? Obviously I could do: (2..100).each do |x| if x % 2 == 0 # my code end end But, obviously (again), that would be pretty stupid. I know I could do something like: i = 2 while i <= 100 # my code i += 2 end I believe I could also write my own custom class that provides its own each method (?). I am almost sure that would be overkill, though. I'm interested in two things: Is it possible to do this with some variation of the standard Range syntax (i.e., (x..y).each)? Either way, what would be the most idiomatic "Ruby way" of accomplishing this (using a Range or otherwise)? Like I said, I'm new to the language; so any guidance you can offer on how to do things in a more typical Ruby style would be much appreciated.

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  • (Python) algorithm to randomly select a key based on proportionality/weight

    - by LaundroMat
    Hi - I'm a bit at a loss as to how to find a clean algorithm for doing the following: Suppose I have a dict k: >>> k = {'A': 68, 'B': 62, 'C': 47, 'D': 16, 'E': 81} I now want to randomly select one of these keys, based on the 'weight' they have in the total (i.e. sum) amount of keys. >>> sum(k.values()) >>> 274 So that there's a >>> 68.0/274.0 >>> 0.24817518248175183 24.81% percent change that A is selected. How would you write an algorithm that takes care of this? In other words, that makes sure that on 10.000 random picks, A will be selected 2.481 times?

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  • Csharp: I am trying to get the top nth values from and rectangular array

    - by user355925
    I am reading a txt file for strings that represent intergers. the file is space delimited. I have created an array[10,2]. evertime the the strings 1~10 is found in the file I increment array[n,0] by 1. I also feed array[n,1] with numbers 1~10. ie txt file contents: 1/1/1 10/1/2001 1 1 10 2 2 3 1 5 10 word word 3 3 etc.. streamreader reads 1/1/1 and determines that is is not 1~10 streamreader reads 10/1/2001 and determines that it is not 1~10 streamreader reads 1 and ++array[0,0] streamreader reads 1 and ++array[0,0] streamreader reads 10 and ++array[9,0] etc.. the result will be: '1' was found 3 times '2' was found 2 times '3' was found 3 times '5' was found 1 time '10' was found 2 times My problem is that I need this array placed in order(sorted) by value of column 0 so that it would be: 1 3 2 10 5

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  • Collection was modified; enumeration operation may not execute

    - by Rita
    I have the below code. I am trying to remove the record and it is throwing Exception when it is removing the Record. "Collection was modified; enumeration operation may not execute." Any ideas on how to get rid of the message. Appreciate your time. //validClaimControlNo has valid ClaimControl Numbers. List<string> validClaimControlNo = new List<string>(); int count = 0; foreach (List<Field> f in records) { foreach (Field fe in f) { if (i == 0) if (!(validClaimControlNo.Contains(fe.Value))) { //if this claim is not in the Valid list, Remove that Record records.RemoveAt(count); } i++; } i = 0; count++; }

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  • PHP split string into integer element and string

    - by David19801
    Hello, I have a string say: Order_num = "0982asdlkj" How can I split that into the 2 variables, with the number element and then another variable with the letter element in php? The number element can be any length from 1 to 4 say and the letter element fills the rest to make every order_num 10 characters long in total. I have found the php explode function...but don't know how to make it in my case because the number of numbers is between 1 and 4 and the letters are random after that, so no way to split at a particular letter. Please help as specifically as possible!

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  • Limiting object allocation over multiple threads

    - by John
    I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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  • group by, order by, with join

    - by Scarface
    Hey guys, quick question, I have this query, and I am trying to get the latest comment for each topic and then sort those results in descending order (therefore one comment per topic). I have what I think should work, but my join always messes my results up. Somehow, it seems to have sorted the end results properly, but has not taken the latest comment from each topic instead it seems to have just taken a random comment. If anyone has any ideas, would really appreciate any advice SELECT * FROM comments JOIN topic ON topic.topic_id=comments.topic_id WHERE topic.creator='admin' GROUP BY comments.topic_id ORDER BY comments.time DESC table comments is structured like id time user message topic_id table topic is structured like topic_id subject_id topic_title creator timestamp description

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  • Forking Multiple Apps Under Python Subprocess

    - by noxtion
    Hello all. I have been looking through Google and SO for something that could help me solve this but I have run into a block. I am a bit new to Python but I am looking for a way to run multiple apps that will continuously run in the background. For example, I need 4 apps to start up with a param -appnum set to a different value. I would like to use python to count up and then start up a new app that will continue to run. I assumed I would use subprocess but I feel a bit overwhelmed by the documentation. I also plan to have the app print out sequences of numbers and would like to redirect this to a file. I noticed some of the SO questions talked about this, but I am a little confused on what to do. -Mike

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  • functions in assembler

    - by stupid_idiot
    hi, i have philosophised about the purpose of stack a little bit and after some coding i figured out what is it's strength. The only thing that lies in my stomache is how does it work with functions? I tried to make some easy function for adding two numbers using universal registers but I suppose that's not how does it work in C for example.. where are all the parameters, local variables and where is the result stored? how would you rewrite this to assembler?(how would compiler for C rewrite it?) int function(int a, int &b, int *c){ return a*(b++)+(*c); } i know this example kinda sucks.. but this way i can understand all the possibilities

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