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Search found 1696 results on 68 pages for 'textbook mistake'.

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• How to drop a primary key using ActiveRecord migrations

  - by knoopx

  Due to a mistake I forgot to add :id => false to a has_many :trough table creation migration. Now I reverted the association back to a has_and_belongs_to_many and ActiveRecord throws an exception complaining about the presence of the primary key. I couldn't find any reference on the ActiveRecord documentation so, do you know if there is any standard, clean way of doing it?

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• regexp exclusion

  - by Vlad

  Hello everyone! I have regexp to change smileys to images. Here it is (?:(?![0]:\)|:\)\)|:-\)\)))(:\)|:-\)) The point is not to change 0:) and :)) and :-)) while changing :) and :-) It works pretty well with :)) and :-)) but somehow still grabs :) in 0:) Where's my mistake?

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• Drawbacks with reading and writing a big file to or from disk at once instead of small chunks?

  - by Johann Gerell

  I work mainly on Windows and Windows CE based systems, where CreateFile, ReadFile and WriteFile are the work horses, no matter if I'm in native Win32 land or in managed .Net land. I have so far never had any obvious problem writing or reading big files in one chunk, as opposed to looping until several smaller chunks are processed. I usually delegate the IO work to a background thread that notifies me when it's done. But looking at file IO tutorials or "textbook examples", I often find the "loop with small chunks" used without any explanation of why it's used instead of the more obvious (I dare to say!) "do it all at once". Are there any drawbacks to the way I do that I haven't understood?

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• How to use MOV instruction in ARM with an immediate number as the second operand

  - by Summer_More_More_Tea

  Hi everyone: I just begin to study ARM assembly language, and am not clear about how to use MOV to transfer an immediate number into a register. From both the ARM reference manual and my textbook, it's said that range of immediate number following MOV instruction is 0-255. But when I test on my own PC in ADS 1.2 IDE, instruction MOV R2, #0xFFFFFFFF performs well. Isn't number 0xFFFFFFFF out of range according to the specification? Hope someone can give me a hand. Regards.

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• Reading all compile errors in Windows command-line?

  - by ArdillaRoja

  Noob question, apologies. I'm compiling Java in Windows Vista's command-line and have so many syntax errors that some are being pushed off the top (a lot of 'class, interface or enum expected' errors which leads me to believe it's an obvious syntax mistake early on in the code that I can't spot). Does anyone know how I could get it to display those first errors? Thanks in advance for the help.

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• What is a practical, real world example of the Linked List?

  - by JStims

  I understand the definition of a Linked List, but how can it be represented and related to a common concept or item? For example, inheritance in OOP can be related to automobiles. All (most) automobiles in real life are the essentially same thing; an automobile has an Engine, you can start() it, you can make the car go(), stop() and so on. An automobile would typically have a maximum passenger capacity but it would differ between a Bus and a SportsCar, which are both automobiles. Is there some real life, intuitive example of the plain ole' singly Linked List like we have with inheritance? The typical textbook Linked List example shows a node with an integer and a pointer to the next, and it just doesn't seem very useful. Your input is appreciated.

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• change session property in zend

  - by Behrang

  I made session using zend authentication it works good but my problem is I want to change some property of it from another action in other controller my code is: $auth = Zend_Auth::getInstance(); if($auth-hasIdentity()) { $blogId = new model_blog request; $auth-getIdentity()-user_current_blog = $blogId; print "Current Blog"; print_r($auth-getIdentity()-user_current_blog); } in this action user_current_blog change but in other action it not works!!! where I made a mistake???

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• Create .alx file in Blackberry eclips

  - by upendra

  Hi Friends, I developed blackberry application in Eclipse its working fine in simulator now i need to create .alx file, so i right click on project then clicked on generate alx file but it is not creating and not giving any error..... can u please tell me any other way to create alx file or i am doing any mistake please give me the suggestion Thanking you

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• Prevent SQL Server Table operations (INSERT and DELETE) on some tables

  - by stckvrflw

  While working with some random sql queries on our databases, we may not want to insert or delete items to some of the database tables by just typing their names by mistake. So how to make them locked to the "editing", to be able to work safe. Thanks.

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• passing form values from one jsp to another

  - by shil

  hi i need to access form data given entered in one jsp in another.. this is how my code looks fisrt jsp: second jsp: <%=request.getParameter("firstame")% now this prints a null value.. what is the mistake here? how do i get to access the values in my second jsp?

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• How can I extract the original image stream from a System.Drawing.Bitmap object?

  - by skolima

  I am embedding images into my assembly using .resx files. Upon runtime, I need to save the images into standalone files, restoring the original content. How can I extract the original file stream from an System.Drawing.Bitmap instance? I know I can create a stream using Bitmap.Save(), but this transcodes (and in effect - inflates) the images, even when saving a PNG back as PNG. Or perhaps my mistake is reading them from Resource as Bitmap in the first place?

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• Matlab code help. Backward Euler method.

  - by m0s

  Here is the matlab/freemat code I got to solve ODE numerically using backward Euler method. However the results are inconsistent with my textbook results, and sometimes even ridiculously inconsistent. Please point out what is wrong with the code. I have already asked this question on mathoverflow.com no help there, hope someone here can help. function [x,y]=backEuler(f,xinit,yinit,xfinal,h) %f - this is your y prime %xinit - initial X %yinit - initial Y %xfinal - final X %h - step size n=(xfinal-xinit)/h; %Calculate steps %Inititialize arrays... %1st elements take xinit and yinit corespondigly, the rest fill with 0s x=[xinit zeros(1,n)]; y=[yinit zeros(1,n)]; %Numeric routine for i=1:n x(i+1)=x(i)+h; ynew=y(i)+h*(f(x(i),y(i))); y(i+1)=y(i)+h*f(x(i+1),ynew); end end

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• Reset ID autoincrement ? phpmyadmin

  - by Marcelo

  Hi, I was testing some data in my tables of my database, to see if there was any error, now I cleaned all the testing data, but my id (auto increment) does not start from 1 anymore, can (how do) I reset it ? Sorry for any mistake in English, and thanks for the attention.

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• How to solve following issue in java?

  - by lakshmi

  Im getting following error while running the query. org.hibernate.hql.ast.QuerySyntaxException: expecting CLOSE, found 'LIMIT' near line 1, column 194 [from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' and gpsdate in (select id.gpsdate from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' ORDER BY id.gpsdate DESC LIMIT 1 ) and gpsstatus='true'] This is my Query.Please give the suggession what is the mistake in this query? data=session.createQuery[from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' and gpsdate in (select id.gpsdate from com.claystone.db.Gpsdata where id.mobileunitid = '2090818044' ORDER BY id.gpsdate DESC LIMIT 1 ) and gpsstatus='true']

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• Overriding or overloading?

  - by atch

  Guys I know this question is silly but just to make sure: Having in my class method: boolean equal(Document d) { //do something } I'm overloading this method nor overriding right? I know that this or similiar question will be on upcoming egzam and would be stupid to not get points for such a simple mistake;

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• ActionScript Bitmap Filter Tweening

  - by TheDarkIn1978

  i can't seem to tween any bitmap filters. here's my code: var dropShadow:DropShadowFilter = new DropShadowFilter(); mySprite.filters = [dropShadow]; var dropShadowTween:Tween = new Tween(dropShadow, "distance", Regular.easeOut, 4.0, 20, 2, true); what is my mistake? i've also tried the following but it doesn't work: var dropShadowTween:Tween = new Tween(mySprite.filters[0], "distance", Regular.easeOut, 4.0, 20, 2, true);

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• ido freezes when a non-existent file match is entered

  - by dericbytes

  Sometimes when I enter a non-existent file match in ido, by mistake, it freezes.... is there an option I can turn off.... it works really well the rest of the time.

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• Automatically creating C# wrappers from c headers?

  - by Winner

  Is there a way to automatically create p/invoke wrappers for .net from a c header? Of course I could create them by hand, but maintaining them would be painful, and I'd probably make a mistake somewhere resulting in hard to debug crashes. I tried SWIG, but it created full classes where simple structs would be sufficient. I'd prefer if the output worked on mono too, but that is not necessary.

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• Write a function in c that includes the following sequence of statements [Wont Compile]

  - by Cody

  There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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• Wordpress: How to be redirected to the page when inserting it's page ID into numeric form input with

  - by Daniel

  I would like to know if there's exists some simple code to get to the page i know its ID , I would like to create small input (no matter where in templates)from where the people can easily get to the page if they know it's page ID (4numeric ID is better to remember - permalink name you can mistake . I have the girls portfolio in wordpress - portfolio=pages x jobs in clubs offers=posts , I would like the girls portfolios to be easily findable by ID(s) , if possible the same for the posts=jobs in clubs The best solution little 4-5numeric input and send=go button in sidebar.php - index.php etc

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• CouchDB Versioning / Auditing

  - by Cory

  I'm attempting to use CouchDB for a system that requires full auditing of all data operations. Because of its built in revision-tracking, couch seemed like an ideal choice. But then I read in the O'Reilly textbook that "CouchDB does not guarantee that older versions are kept around." I can't seem to find much more documentation on this point, or how couch deals with its revision-tracking internally. Is there any way to configure couch either on a per-database, or per-document level to keep all versions around forever? If so, how?

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• Kernel thread exit in linux

  - by Raffo

  Hi guys, I'm here to ask you the difference between a process and a thread in linux. I know that a thread for linux is just a "task", which shares with the father process things that they need to have in common (the address space and other important informations). I also know that the two are creating calling the same function ('clone()'), but there's still something that I'm missing: what really happens when a thread exit? What function is called inside the linux kernel? I know that when a process exits calls the do_exit function, but here or somewhere else there should be a way to understand if it is just a thread exiting or a whole process. Can you explain me this thing or redirect to some textbook?? I tried 'Understanding the linux kernel' but I was not satisfied with it. I'm asking this thing because a need to add things to the task_struct struct, but I need to discriminate how to manage those informations for a process and its children. Thank you.

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• Passing URL as parameter using mod_rewrite

  - by Dusan

  I would like to rewrite dynamic URL /index.php?pid=login&redirect=/previous-page.html to something like this /login.html-r-previous-page.html I tried this RewriteRule ^login.html-r-(.*)$ /index.php?pid=login&redirect=$1 [L] But no succes. I was also trying to change the regex to .+ or some other forms, but it seems useless. Maybe I am making mistake somewhere else. I am new to regular expressions and also mod_rewrite. Thank you for help

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• What's the logical value of "string" in python?

  - by Kamran

  I erroneously wrote this code in python: name = input("what is your name?") if name == "Kamran" or "Samaneh": print("That is a nice name") else: print("You have a boring name ;)") It always prints out "That is a nice name" even when the input is neither "Kamran" nor "Samaneh". Am I correct in saying that it considers "Samaneh" as a true? why? By the way, I already noticed my mistake. The correct form is: if name == "Kamran" or name == "Samaneh":

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• Problem in converting ToDictionary<Datetime,double>() using LINQ(C#3.0)

  - by Newbie

  I have written the below return (from p in returnObject.Portfolios.ToList() from childData in p.ChildData.ToList() from retuns in p.Returns.ToList() select new Dictionary<DateTime, double> () { p.EndDate, retuns.Value } ).ToDictionary<DateTime,double>(); Getting error No overload for method 'Add' takes '1' arguments Where I am making the mistake I am using C#3.0 Thanks

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