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  • a completely decoupled OO system ?

    - by shrini1000
    To make an OO system as decoupled as possible, I'm thinking of the following approach: 1) we run an RMI/directory like service where objects can register and discover each other. They talk to this service through an interface 2) we run a messaging service to which objects can publish messages, and register subscription callbacks. Again, this happens through interfaces 3) when object A wants to invoke a method on object B, it discovers the target object's unique identity through #1 above, and publishes a message on the message service for object B 4) message services invokes B's callback to give it the message 5) B processes the request and sends the response for A on message service 6) A's callback is called and it gets the response. I feel this system is as decoupled as practically possible, but it has the following problems: 1) communication is typically asynchronous 2) hence it's non real time 3) the system as a whole is less efficient. Are there any other practical problems where this design obviously won't be applicable ? What are your thoughts on this design in general ?

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  • Optimize master-detail insert statements

    - by Dave Jarvis
    Quest After a day of running (against nearly 1 GB of data), a set of statements are tumbling down to 40 inserts per second. I am looking to increase that by an order of magnitude or two. SQL Code The code to insert the information comes in two parts: a master record and detail records. The master record: INSERT INTO MONTH_REF (DISTRICT_ID, STATION_ID, CATEGORY_ID, YEAR, MONTH) VALUES ('101', '0066', '010', 1984, 07); The detail records: INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES ((SELECT ID FROM MONTH_REF M WHERE M.DISTRICT_ID = '101' AND M.STATION_ID = '0066' AND M.CAT EGORY_ID = '010' AND M.YEAR = 1984 AND M.MONTH = 07), 0, ' ', 1); INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES ((SELECT ID FROM MONTH_REF M WHERE M.DISTRICT_ID = '101' AND M.STATION_ID = '0066' AND M.CAT EGORY_ID = '010' AND M.YEAR = 1984 AND M.MONTH = 07), 0.5, ' ', 2); INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES ((SELECT ID FROM MONTH_REF M WHERE M.DISTRICT_ID = '101' AND M.STATION_ID = '0066' AND M.CAT EGORY_ID = '010' AND M.YEAR = 1984 AND M.MONTH = 07), 0, 'T', 3); Proposed Solution INSERT INTO MONTH_REF (DISTRICT_ID, STATION_ID, CATEGORY_ID, YEAR, MONTH) VALUES ('101', '0066', '010', 1984, 07); SET @month_ref_id := (SELECT LAST_INSERT_ID()); INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES (@month_ref_id, 0, ' ', 1); INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES (@month_ref_id, 0.5, ' ', 2); INSERT INTO DAILY (MONTH_REF_ID, AMOUNT, DAILY_FLAG_ID, DAY) VALUES (@month_ref_id, 0, 'T', 3); Constraints The MONTH_REF table has an AUTO_INCREMENT primary key and is indexed on it. The DAILY table has no index and no primary key. A primary key can be added to the DAILY table, if it would help. Question Is there a more efficient way to execute the (billion or so) insert statements than the proposed solution? Thank you!

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  • Questions about my program and Polymorphism

    - by Strobe_
    Ok, so basically I'm creating a program which allows the user to select a shape (triangle, square, circle) and then it takes in a int and calculates the boundary length and area. I have no problem doing this and have a program that's working perfectly. (https://gist.github.com/anonymous/c63a03c129560a7b7434 4 classes) But now I have to implement this with polymorphism concepts and I'm honestly struggling as to how to do it. I have a basic idea of what I want to do when it comes to inheritance Main | Shapes / | \ triangle circle square But I don't understand how I'm supposed to override when all the methods within the triangle/square/circle classes are unique, there are no "abstract" methods as such that I could inherit from the "Shapes" class. If somebody could make look quickly at the code I linked and suggest a way to do this it would be much appreciated. Sorry if I was bad at explaining this. Thanks.

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  • concatenate multi values in one record without duplication

    - by mikehjun
    I have a dbf table like below which is the result of one to many join from two tables. I want to have unique zone values from one Taxlot id field. table name: input table tid ----- zone 1 ------ A 1 ------ A 1 ------ B 1 ------ C 2 ------ D 2 ------ E 3 ------ C Desirable output table table name: input table tid ----- zone 1 ------ A, B, C 2 ------ D, E 3 ------ C I got some help but couldn't make it to work. inputTbl = r"C:\temp\input.dbf" taxIdZoningDict = {} searchRows = gp.searchcursor(inputTbl) searchRow = searchRows.next() while searchRow: if searchRow.TID in taxIdZoningDict: taxIdZoningDict[searchRow.TID].add(searchRow.ZONE) else: taxIdZoningDict[searchRow.TID] = set() #a set prevents dulpicates! taxIdZoningDict[searchRow.TID].add(searchRow.ZONE) searchRow = searchRows.next() outputTbl = r"C:\temp\output.dbf" gp.CreateTable_management(r"C:\temp", "output.dbf") gp.AddField_management(outputTbl, "TID", "LONG") gp.AddField_management(outputTbl, "ZONES", "TEXT", "", "", "20") tidList = taxIdZoningDict.keys() tidList.sort() #sorts in ascending order insertRows = gp.insertcursor(outputTbl) for tid in tidList: concatString = "" for zone in taxIdZoningDict[tid] concatString = concatString + zone + "," insertRow = insertRows.newrow() insertRow.TID = tid insertRow.ZONES = concatString[:-1] insertRows.insertrow(insertRow) del insertRow del insertRows

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  • Should I aim for fewer HTTP requests or more cacheable CSS files?

    - by Jonathan Hanson
    We're being told that fewer HTTP requests per page load is a Good Thing. The extreme form of that for CSS would be to have a single, unique CSS file per page, with any shared site-wide styles duplicated in each file. But there's a trade off there. If you have separate shared global CSS files, they can be cached once when the front page is loaded and then re-used on multiple pages, thereby reducing the necessary size of the page-specific CSS files. So which is better in real-world practice? Shorter CSS files through multiple discrete CSS files that are cacheable, or fewer HTTP requests through fewer-but-larger CSS files?

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  • insert into several inheritance tables with OUTPUT - sql servr 2005

    - by csetzkorn
    Hi, I have a bunch of items – for simplicity reasons – a flat table with unique names seeded via bulk insert: create table #items ( ItemName NVARCHAR(255) ) The database has this structure: create table Statements ( Id INT IDENTITY NOT NULL, Version INT not null, FurtherDetails varchar(max) null, ProposalDateTime DATETIME null, UpdateDateTime DATETIME null, ProposerFk INT null, UpdaterFk INT null, primary key (Id) ) create table Item ( StatementFk INT not null, ItemName NVARCHAR(255) null, primary key (StatementFk) ) Here Item is a child of Statement (inheritance). I would like to insert items in #items using a set based approach (avoiding triggers and loops). Can this be achieved with OUTPUT in my scenario. A ‘loop based’ approach is just too slow where I use something like this: insert into Statements (Version, FurtherDetails, ProposalDateTime, UpdateDateTime, ProposerFk, UpdaterFk) VALUES (1, null, getdate(), getdate(), @user_id, @user_id) etc. This is a start for the OUTPUT based approach – but I am not sure whether this would work in my case as ItemName is only inserted into Item: insert into Statements ( Version, FurtherDetails, ProposalDateTime, UpdateDateTime, ProposerFk, UpdaterFk ) output inserted.Id ... ??? Thanks. Best wishes, Christian

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  • Does Microsoft Access use the PK fields for anything?

    - by chrismay
    Ok this is going to sound strange, but I have inherited an app that is an Access front end with a SQL Server backend. I am in the process of writing a new front end for it, but... we need to continue using the access front end for a while even after we deploy my new front end for reasons I won't go into. So both the existing Access app and my new app will need to be able to access and work with the data. The problem is the database design is a nightmare. For example some simple parent-child table relationships have like 4 and 5 part composite primary keys. I would REALLY like to remove these PKs and replace them with unique constraints or whatever, and add a new column to each of these tables called ID that is just an identity. If I change the PK and FKs on these tables to more managable fields, will the Access app have problems? What I mean is, does access use the meta data from the tables (PK and FK info) in such a way that it would break the app to change these?

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  • Saving an IP adddress to DB

    - by Mark
    I want to save a user's IP address to my database just in case any legal issues come up and we need to track down who performed what action. Since I highly doubt I will ever actually need to use this data (well, maybe for counting unique hits or something) do you think I can just dump the REMOTE_ADDR into a field? If so, what should the length of that field be? 39 chars should fit an IPv6 address, no? I don't know if I'll ever get any of those, but just in case...

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  • More than one profile in Django?

    - by JPC
    Is it possible to use Django's user authentication features with more than one profile? Currently I have a settings.py file that has this in it: AUTH_PROFILE_MODULE = 'auth.UserProfileA' and a models.py file that has this in it: from django.db import models from django.contrib.auth.models import User class UserProfileA(models.Model): company = models.CharField(max_length=30) user = models.ForeignKey(User, unique=True) that way, if a user logs in, I can easily get the profile because the User has a get_profile() method. However, I would like to add UserProfileB. From looking around a bit, it seems that the starting point is to create a superclass to use as the AUTH_PROFILE_MODULE and have both UserProfileA and UserProfileB inherit from that superclass. The problem is, I don't think the get_profile() method returns the correct profile. It would return an instance of the superclass. I come from a java background (polymorphism) so I'm not sure exactly what I should be doing. Thanks!

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  • JAXB code generation: how to remove a zero occurrence field?

    - by reef
    Hi all, I use JAXB 2.1 to generate Java classes from several XSD files, and I have a problem related to complex type restriction. On of the restrictions modifies the occurence configuration from minOccurs="0" maxOccurs="unbounded" to minOccurs="0" maxOccurs="0". Thus this field is not needed anymore in the restricted type. But actually JAXB generates the restricted class with a [0..1] cardinality instead of 0. By the way the generation is tuned with <xjc:treatRestrictionLikeNewType / so that a XSD restriction is not mapped to a Java class inheritance. Here is an example: Here is the way a field is defined in a complex type A: <element name="qualifier" type="CR" maxOccurs="unbounded" minOccurs="0"/ Here is the way the same field is restricted in another complex type B that restricts A: <element name="qualifier" type="CR" minOccurs="0" maxOccurs="0"/ In the A generated class I have: @XmlElement(name = "qualifier") protected List<CR qualifiers; And in the B generated class I have: protected CR qualifiers; With my poor understanding of JAXB the absence of the XmlElement annotation tells JAXB not to marshall/unmarshall this field. Am I wrong? If I am right is there a way to tell JAXB not to generate the qualifiers field at all? This would be in my opinion a much better generation as it respects the constraints. Any idea, thougths on the topic? Thanks!!

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  • How to access a website's url programmatically from within the page

    - by Jeff
    For work, I am working on a site that has a feature that lets users make custom instances of the site depending on who they want to show it to. So if they want to show their potential employer a little bit about themselves, they can send them a custom url, that has a uid on the end of it that tells the database what to show and what not to when the site is loaded up. Now, I need to be able to take the value that is on the end of the url, this unique uid that corresponds with their preferences in the db, accessable on run time. Meaning that when someone types in this custom url, I need to be able to show the name of the person whose portfolio is being viewed BEFORE password authentication takes place... If I could get the URL, I suppose I could parse through it to find the necessary UID...but how do I get the url? Maybe I am just missing something here, but if anyone has any thoughts or ideas, it would be appreciated!! Thanks

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  • How to handle set based consistency validation in CQRS?

    - by JD Courtoy
    I have a fairly simple domain model involving a list of Facility aggregate roots. Given that I'm using CQRS and an event-bus to handle events raised from the domain, how could you handle validation on sets? For example, say I have the following requirement: Facility's must have a unique name. Since I'm using an eventually consistent database on the query side, the data in it is not guaranteed to be accurate at the time the event processesor processes the event. For example, a FacilityCreatedEvent is in the query database event processing queue waiting to be processed and written into the database. A new CreateFacilityCommand is sent to the domain to be processed. The domain services query the read database to see if there are any other Facility's registered already with that name, but returns false because the CreateNewFacilityEvent has not yet been processed and written to the store. The new CreateFacilityCommand will now succeed and throw up another FacilityCreatedEvent which would blow up when the event processor tries to write it into the database and finds that another Facility already exists with that name.

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  • How to 'insert if not exists' in MySQL?

    - by warren
    I started by googling, and found this article which talks about mutex tables. I have a table with ~14 million records. If I want to add more data in the same format, is there a way to ensure the record I want to insert does not already exist without using a pair of queries (ie, one query to check and one to insert is the result set is empty)? Does a unique constraint on a field guarantee the insert will fail if it's already there? It seems that with merely a constraint, when I issue the insert via php, the script croaks.

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  • How to filter node list based on the contents of another node list

    - by ~otakuj462
    Hi, I'd like to use XSLT to filter a node list based on the contents of another node list. Specifically, I'd like to filter a node list such that elements with identical id attributes are eliminated from the resulting node list. Priority should be given to one of the two node lists. The way I originally imagined implementing this was to do something like this: <xsl:variable name="filteredList1" select="$list1[not($list2[@id_from_list1 = @id_from_list2])]"/> The problem is that the context node changes in the predicate for $list2, so I don't have access to attribute @id_from_list1. Due to these scoping constraints, it's not clear to me how I would be able to refer to an attribute from the outer node list using nested predicates in this fashion. To get around the issue of the context node, I've tried to create a solution involving a for-each loop, like the following: <xsl:variable name="filteredList1"> <xsl:for-each select="$list1"> <xsl:variable name="id_from_list1" select="@id_from_list1"/> <xsl:if test="not($list2[@id_from_list2 = $id_from_list1])"> <xsl:copy-of select="."/> </xsl:if> </xsl:for-each> </xsl:variable> But this doesn't work correctly. It's also not clear to me how it fails... Using the above technique, filteredList1 has a length of 1, but appears to be empty. It's strange behaviour, and anyhow, I feel there must be a more elegant approach. I'd appreciate any guidance anyone can offer. Thanks.

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  • How to remove a single event in a recuring event

    - by albertos
    hi all. I' m having an issue with fullCalendar. I created a script that, adds an event to fullCalendar, along a day range, and set a unique id in order to have this event recur. let say for example that i have a recuring event from 1/1/10 till 10/1/10. i create 10 single event Objects with the same id, and place then on fullCalendar. my question is, that i want to exclude a single day over this recuring event. (for example 3/1/10). i found out, that if i remove that particural event from the sources table and then update the event its fine. but how can i get on runtime the actucal index of this eventObj on sources table? Note that, i add the events on the fullCalendar using the .fullCalendar("renderEvent") method. Thanks.

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  • GWT Strength compared to other framework??

    - by Noor
    One of the main strength of GWT is to code in java and everything gets compiled and is loaded by several browsers through gwt deferred binding?? Apart from this, i.e. working only on a single code base, do GWT has any other advantage compared to other existing framework?? Edit: I'm trying to say why should we use gwt and not another framework?? What is there in GWT that makes it special for web application development?? What GWT makes for us and another framework or toolkit don't do?? As i said above GWT makes deferred binding which is a plus, so I wanted what other things it do that makes it special and unique??

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  • Should HTTP POST be discouraged?

    - by Tomas Sedovic
    Quoting from the CouchDB documentation: It is recommended that you avoid POST when possible, because proxies and other network intermediaries will occasionally resend POST requests, which can result in duplicate document creation. To my understanding, this should not be happening on the protocol level (a confused user armed with a doubleclick is a completely different story). What is the best course of action, then? Should we really try to avoid POST requests and replace them by PUT? I don't like that as they convey a different meaning. Should we anticipate this and protect the requests by unique IDs where we want to avoid accidental duplication? I don't like that either: it complicates the code and prevents situations where multiple identical posts may be desired.

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  • Capacity Allocation

    - by user1708730
    I am new to VB in Excel. I have a unique requirement for capacity allocation which I want to automate using excel VB and facing hard time doing so, hope you can help. The objective is to maximize profit by allocating maximum capacity to those products which have highest profit potential first. Every Month I get demand along with backlogs of previous month. I need to allocate capacity to backlogs of previous month first and then only the remaining capacity for fresh demand. There are two primary constraints: 1.The number of working days in a month (variable) 2. Not all products can be made on every production line and out of same product may be different for each production line Also there will be losses whenever there is a change over from one SKU to another depending upon the Variant Type and size of next product. If there is variant change then 8 hours of production loss needs to be accounted and 4 hours in case of size change(8 hours in case of both). I have attached sample data(Actual data has 10 production lines and 50 products) https://rapidshare.com/files/1822719405/Sample%20Data.xlsx?bin=1 Thanks in advance for help!

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  • How to find nearest week day for an arbitrary date?

    - by Stig Brautaset
    Is there a more elegant way than the below to find the nearest day of the week for a given date using JodaTime? I initially thought setCopy() would be it, but this sets the day to the particular day in the same week. Thus, if ld is 2011-11-27 and day is "Monday" the following function returns 2011-11-21, and not 2011-11-28 as I want. // Note that "day" can be _any_ day of the week, not just weekdays. LocalDate getNearestDayOfWeek(LocalDate ld, String day) { return ld.dayOfWeek().setCopy(day); } Below is a work-around I came up with that works for the particular constraints in my current situation, but I'd love to get help find a completely generic solution that works always. LocalDate getNearestDayOfWeek(LocalDate ld, String day) { LocalDate target = ld.dayOfWeek().setCopy(day); if (ld.getDayOfWeek() > DateTimeConstants.SATURDAY) { target = target.plusWeeks(1); } return target; } Looking more into this I came up with this, which seems to be a more correct solution, though it seems awfully complicated: LocalDate getNearestDayOfWeek(LocalDate ld, String day) { LocalDate target = ld.dayOfWeek().setCopy(day); if (target.isBefore(ld)) { LocalDate nextTarget = target.plusWeeks(1); Duration sincePrevious = new Duration(target.toDateMidnight(), ld.toDateMidnight()); Duration untilNext = new Duration(ld.toDateMidnight(), nextTarget.toDateMidnight()); if (sincePrevious.isLongerThan(untilNext)) { target = nextTarget; } } return target; }

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  • Customizing the Stars Image for Ajaxful_Rating RoR plugin

    - by Kevin
    I'm trying to come up with my own star image that's slightly smaller and different style than the one provided in the gem/plugin, but Ajaxful_rating doesn't have an easy way to do this. Here's what I've figured out so far: The stars.png in the public folder is three 25x25 pixel tiles stacked vertically, ordered empty star, normal star, and hover star. I'm assuming as long as you keep the above constraints, you should be fine without modifying any other files. But what if you want to change the image size of the stars to larger or smaller? I've found where you can change the height in the stylesheets/ajaxful_rating.css .ajaxful-rating{ position: relative; /*width: 125px; this is setted dynamically */ height: 25px; overflow: hidden; list-style: none; margin: 0; padding: 0; background-position: left top; } .ajaxful-rating li{ display: inline; } .ajaxful-rating a, .ajaxful-rating span, .ajaxful-rating .show-value{ position: absolute; top: 0; left: 0; text-indent: -1000em; height: 25px; line-height: 25px; outline: none; overflow: hidden; border: none; } You just need to change every place that says "25px" above to whatever height your new star image is. This works fine but doesn't display the horizontal part correctly. Anyone know where I would look to set the horizontal part as well? (I'm assuming it's in an .rb file somewhere based upon how many stars you specified in your ajaxful_rating setup)

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  • Could someone give me their two cents on this optimization strategy

    - by jimstandard
    Background: I am writing a matching script in python that will match records of a transaction in one database to names of customers in another database. The complexity is that names are not unique and can be represented multiple different ways from transaction to transaction. Rather than doing multiple queries on the database (which is pretty slow) would it be faster to get all of the records where the last name (which in this case we will say never changes) is "Smith" and then have all of those records loaded into memory as you go though each looking for matches for a specific "John Smith" using various data points. Would this be faster, is it feasible in python, and if so does anyone have any recommendations for how to do it?

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  • Django: Extending User Model - Inline User fields in UserProfile

    - by Jack Sparrow
    Is there a way to display User fields under a form that adds/edits a UserProfile model? I am extending default Django User model like this: class UserProfile(models.Model): user = models.OneToOneField(User, unique=True) about = models.TextField(blank=True) I know that it is possible to make a: class UserProfileInlineAdmin(admin.TabularInline): and then inline this in User ModelAdmin but I want to achieve the opposite effect, something like inverse inlining, displaying the fields of the model pointed by the OneToOne Relationship (User) in the page of the model defining the relationship (UserProfile). I don't care if it would be in the admin or in a custom view/template. I just need to know how to achieve this. I've been struggling with ModelForms and Formsets, I know the answer is somewhere there, but my little experience in Django doesn't allow me to come up with the solution yet. A little example would be really helpful!

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  • Randomly sorting an array

    - by Cam
    Does there exist an algorithm which, given an ordered list of symbols {a1, a2, a3, ..., ak}, produces in O(n) time a new list of the same symbols in a random order without bias? "Without bias" means the probability that any symbol s will end up in some position p in the list is 1/k. Assume it is possible to generate a non-biased integer from 1-k inclusive in O(1) time. Also assume that O(1) element access/mutation is possible, and that it is possible to create a new list of size k in O(k) time. In particular, I would be interested in a 'generative' algorithm. That is, I would be interested in an algorithm that has O(1) initial overhead, and then produces a new element for each slot in the list, taking O(1) time per slot. If no solution exists to the problem as described, I would still like to know about solutions that do not meet my constraints in one or more of the following ways (and/or in other ways if necessary): the time complexity is worse than O(n). the algorithm is biased with regards to the final positions of the symbols. the algorithm is not generative. I should add that this problem appears to be the same as the problem of randomly sorting the integers from 1-k, since we can sort the list of integers from 1-k and then for each integer i in the new list, we can produce the symbol ai.

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  • How do I trigger a single event defined for a class of objects

    - by mrbinky3000
    I have a question. I have 8 buttons that have unique incrementing id's and a shared class. <button class="btnChapter" id="btnChapter_1" value="1">1</button> <button class="btnChapter" id="btnChapter_2" value="2">2</button> <button class="btnChapter" id="btnChapter_3" value="3">3</button> ... In order to prevent me from duplicating code, I bound a click event to the btnChapter class instead of binding an event individually to each button's ID. $('.btnChapter').click(function(){ .. do stuff .. }); How do I trigger() the click() event only for #btnChapter_2? The following doesn't seem to work. $('#btnChapter_2').click()

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  • Removing Duplicates in an array in C

    - by LuckySlevin
    The question is a little complex. The problem here is to get rid of duplicates and save the unique elements of array into another array with their original sequence. For example : If the input is entered b a c a d t The result should be : b a c d t in the exact state that the input entered. So, for sorting the array then checking couldn't work since I lost the original sequence. I was advised to use array of indices but I don't know how to do. So what is your advise to do that?

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