breadth first search - Page 609

list permutations in haskell

- by turingcomplete

So I'm new to haskell and I've been playing with it for a while now. I want to get my function that outputs all list permutations to work. I have written 2 implementations, one works well, the other is giving me an error. Any help would be awesome. This is the first (working) implementation: permute [] = [[]] permute xs = [y| x <- xs, y <- map (x:) $ permute $ delete x xs] This one is giving me an error: permute [] = [[]] permute xs = map (\x -> map (x:) $ permute $ delete x xs) xs and here's the error message: Occurs check: cannot construct the infinite type: t0 = [t0] Expected type: [t0] Actual type: [[t0]] In the expression: map (x :) $ permute $ delete x xs In the first argument of `map', namely `(\ x -> map (x :) $ permute $ delete x xs)' I'd appreciate if someone could explain why I'm getting this error. Thanks

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Why the compiler doesn't complain about this error ?

- by M.H

Hi I am writing some java questions to help my friends in the java exam. I wrote a question and I supposed that three errors will occurred in the code but the compiler complained only about two. the code is : class MyClass { static MyClass() { System.out.println("I am The First Statement here!"); this(); } } I expected the following errors : the constructor can't be static this can't be in a static function (since the constructor isn't valid) this here should be the first statement. NetBeans isn't complaining about the second error here. why ?

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Using fixtures with factory_girl

- by deb

When building the following factory: Factory.define :user do |f| f.sequence(:name) { |n| "foo#{n}" } f.resume_type_id { ResumeType.first.id } end ResumeType.first returns nil and I get an error. ResumeType records are loaded via fixtures. I checked using the console and the entries are there, the table is not empty. I've found a similar example in the factory_girl mailing list, and it's supposed to work. What am I missing? Do I have to somehow tell factory_girl to set up the fixtures before running the tests?

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What's the difference between /123 and /?123?

- by BoltClock

I've noticed that some sites (including http://jobs.stackoverflow.com) have query strings that look like this: http://somewebapp.example/?123 as compared to: http://somewebapp.example/123 or http://somewebapp.example/id/123 What are the reasons that developers choose to implement their web apps' URLs using the first example instead of the second and third examples? And as a bonus, how would one implement the first example in PHP, given that 123 is the primary key of some row in a database table? (I just need to know how to retrieve 123 from the URL; I already know how to query the database for a primary key of 123.)

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Why do the following expanded if shorthand statements not work in javascript?

- by PeanutsMonkey

This is my first attempt to write shorthand if statements however am befuddled by why the expanded versions don't work quite the way I imagined they would. Code 1 - Does not work if(document.getElementById == true) { alert("The document object model is supported by: " + navigator.appName); } Code 2 - Does work if(document.getElementById != false) { alert("The document object model is supported by: " + navigator.appName); } Code 3 - The shorthand that does work if(document.getElementById) { alert("The document object model is supported by: " + navigator.appName); } Why is that if I expand the shorthand in 3 to the first code sample not work and why does it work if I have it equal to != false?

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PHP, PEAR, and oci8 configuration

- by zack_falcon

I'll make this quick. I installed Oracle 11g (with appropriate database, users, etc), Apache 2.4.6, and PHP 5.5.4 on a Fedora 19 system. I wanted to connect PHP to Oracle. What I really wanted to do was to download MDB2_Driver_oci8, which I thought would be easy, but before I can do such a thing, PHP needs to have that plug-in enabled, so here's what I did: Tried to install oci8 via the following: pecl install oci8 When that didn't exactly work the first few times, I figured out I, for some reason, needed "Development tools" - via yum groupinstall "Development Tools" Then I figured out later that PHP actually doesn't do oci8 - it's PHP Devel. So, I had to install that too, via yum install php-devel. And then, I finally got to install oci8. It asked for the Oracle Directory, and that was that. But it said the following: Configuration option 'php_ini' is not set to php.ini location You should add 'extensions=oci8.so' to php.ini First, I did a locate oci8.so - found it in /usr/lib64/php/modules/ Second, I added what it told me to, to the php.ini file. Third, I checked the usual php_info() test page - no mention of OCI8. Uh-oh. Fourth, running both php -i and php -m listed oci8 as one of the modules. Weird. In desperation, I went ahead and downloaded the MDB2_Driver_oci8. Maybe that will fix things. Nope. When I loaded my PHP Webpage, it returned the following: Error message: extension oci8 is not compiled into PHP As well as: MDB2 error: not found Strange. And then I decided to check the error logs: PHP Startup - unable to load dynamic library '/usr/lib64/php/modules/oci8.so' - libclntsh.so.11.1: cannot open shared object file: No such file or directory in Unknown on line 0 And now I'm stuck. I tried going into the php.ini, and found that the extension_dir was commented out. I put it back in, which only seemed to break stuff. Things of note: I followed this (link) guide on how to configure PHP and install oci8. ./configure --with-oci8 doesn't work. Fedora says no such directory. As both the webpage files and the actual server reside on the same PC, I did not install the Oracle Client files. The extension_dir is commented out by default in the php.ini. This is just one of my problems in a long line of problems concerning the replication of an already existing and working, but dying, setup. It seems whenever I want to solve a problem, I have to do X first. And by doing X, I uncover another problem, which I have to solve by doing Y, which has its own problems, etc, etc. Any help would be much appreciated. Thanks.

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Does AsEnumerable() cache all result (LINQ)

- by Akshay

When we call a query operator on a sequence, a sequence-specific operator gets called. I mean if i call Where<>() operator on IEnumerable<>, the operator that will be called will be defined in Enumerable class and if it's called on IQueryable<>, the one defined in Queryable class will be called. Consider the operator Reverse, defined in the Enumerable class. If i want to call it on Iqueryable<> then I must use the AsEnumerable<>() operator to first convert it into IEnumerable<>. db.Countries.OrderBy(cntry=>cntry.CountryName).AsEnumerable().Reverse() But the Reverse operator got to have all records at the same time so that it can reverse them. In the above code do all the records get loaded in memory first and then the Reverse() operator is reversing it ?

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How do I resolve this scope issue in VB .NET?

- by froadie

I have a code structure something like this: For row = 1 To numRows Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Next Dim arrayIndex As Integer = 0 For column As Integer = bucketStartColumn To bucketEndColumn ' whatever code arrayIndex = arrayIndex + 1 Next Not exactly the code, so I don't really need suggestions about refactoring, but my problem is this - with this code I get a compiler error for the first Dim arrayIndex As Integer = 0 - "Variable 'arrayIndex' hides a variable in an enclosing block." As far as I can tell, arrayIndex is local to the first for loop and shouldn't exist by the time we reach the second loop. If I try to change the second declaration of arrayIndex to arrayIndex = 0, I get the error "Name 'arrayIndex' is not declared", as I expected. So is it visible, or not? Does this have something to do with the Dim keyword? Any suggestions of how to get around this, other than naming the second index variable something else?

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Making Django ignore string literals

- by James

UPDATE: It turns out this is a deeper question than I thought at first glance - the issue is that python is replacing the string literals before they ever get to django. I will do more investigating and update this if I find a solution. I'm using django to work with LaTeX templates for report generation, and am running into a lot of problems with the way Django replaces parts of strings. Specficially, I've run into two problems where I try to insert a variable containing latex code. The first was that it would replace HTML characters, such as the less than symbol, with their HTML codes, which are of course gibberish to a LaTeX interpreter. I fixed this by setting the context to never autoescape, like so: c = Context(inputs) c.autoescape = False However, I still have my second issue, which is that Django replaces string literals with their corresponding characers, so a double backslash becomes \, and \b becomes a backspace. How can I force Django to leave these characters in place, so inputs['variable'] = '{\bf this is code} \\' won't get mangled when I use {{variable}} to reference it in the django template?

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margin-bottom property of a div's last element doesn't "extend" the div

- by kitsched

I have an element in a div, which has a background image. Below the div I have another div with another background image. Now the problem is that if the last element contained in the first div has margin-bottom applied there will be a gap between the 2 divs like this: Notice the gray gap caused by the margin-bottom property of the h2 element contained within the first div. I know this can be solved if I switch margin-bottom to padding-bottom but what if I need margin-bottom? How to fix this?

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Cascading Dropdown List

- by user333831

I am working on a web app and trying to code a form with two dropdown lists. The list in the second dropdown will be dependent on the selection from the first one. The task itself isn’t too complicated except that once the first selection is made, I need to make a database call to pull the data for the second dropdown. This is where I am having difficulty. Both lists are in fact populated from a database. I am working on this in a python script and have been trying to do this w/ an onChange javascript function. The web app is built in Zope and page templates may be an option along w/ the python scripts.

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DTPicker: how to open up an control expanded (by default)?

- by Olli

Hi all, in my windows form (Visual C++ 6.0) I'm using an Active x control called "CDTPicker" (CDTPicker : public CWnd). My control is opened up by the click event of another button. like this (works fine): void CProducerDlg::OnSelect() { ... m_wndDatePicker.SetValue(varVariant); // hide date combo box if first entry has been chosen m_wndDate.ShowWindow(SW_HIDE); // show date picker if first entry is chosen m_wndDatePicker.ShowWindow(SW_SHOW); // open up calendar view [tbd] ... } What I need is the calendar view to open up expanded (showing the complete month). I don't find any method to do this... Who can help me? Thanks in advance Olli

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a Facebook app beginner question

- by Robert

Dear all, I have written up my first php script to learn facebook API stuff.It goes like this: require_once('facebook/client/facebook.php'); $facebook = new Facebook('0fff13540b7ff2ae94be38463cb4fa67','8a029798dd463be6c94cb8d9ca851696'); http://stackoverflow.com/questions/ask $fb_user = $facebook-require_login(); ? Hello ' useyou='false' possessive='true' /! Welcome to my first application! I put "facebook.php" in the same directory as my php script. However,after I deploy the php on a web server and link it with facebook and run it,I got error saying: "Fatal error: Call to undefined method Facebook::require_login() in /home/a2660104/public_html/facebook-php-sdk-94fcb13/src/default.php on line 16" Could anyone help me a bit on this?I am a beginner to the facebook app programming.Thanks a lot!

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How to query range of data in DB2 with highest performance?

- by Fuangwith S.

Usually, I need to retrieve data from a table in some range; for example, a separate page for each search result. In MySQL I use LIMIT keyword but in DB2 I don't know. Now I use this query for retrieve range of data. SELECT * FROM( SELECT SMALLINT(RANK() OVER(ORDER BY NAME DESC)) AS RUNNING_NO , DATA_KEY_VALUE , SHOW_PRIORITY FROM EMPLOYEE WHERE NAME LIKE 'DEL%' ORDER BY NAME DESC FETCH FIRST 20 ROWS ONLY ) AS TMP ORDER BY TMP.RUNNING_NO ASC FETCH FIRST 10 ROWS ONLY but I know it's bad style. So, how to query for highest performance?

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Escape characters in MySQL, in Ruby

- by Swards

I have a couple escaped characters in user-entered fields that I can't figure out. I know they are the "smart" single and double quotes, but I don't know how to search for them in mysql. The characters in ruby, when output from Ruby look like \222, \223, \224 etc irb> "\222".length => 1 So - do you know how to search for these in mysql? When I look in mysql, they look like '?'. I'd like to find all records that have this character in the text field. I tried mysql> select id from table where field LIKE '%\222%' but that did not work. Some more information - after doing a mysqldump, this is how one of the characters is represented - '\\xE2\\x80\\x99'. It's the smart single quote. Ultimately, I'm building an RTF file and the characters are coming out completely wrong, so I'm trying to replace them with 'dumb' quotes for now. I was able to do a gsub(/\222\, "'"). Thanks.

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mysql add auto increment and a additional key

- by Lee

Hey all I am trying to alter a table with adding a new column setting it as auto increment and with a key. The table already has one key and this one will be an addition. The error I get is the following. error : Multiple primary key defined My code is: alter table user add column id int (11) NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST; I have also tries wrapping the key name ie alter table user add column id int (11) NOT NULL AUTO_INCREMENT PRIMARY (id) KEY FIRST; But still no luck. How can it be done ?

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The unary increment operator in pointer arithmetic

- by RhymesWithDuck

Hello, this is my first post. I have this function for reversing a string in C that I found. void reverse(char* c) { if (*c != 0) { reverse(c + 1); } printf("%c",*c); } It works fine but if I replace: reverse(c + 1); with: reverse(++c); the first character of the original string is truncated. My question is why would are the statements not equivalent in this instance? Thanks

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Statistical analysis on large data set to be published on the web

- by dassouki

I have a non-computer related data logger, that collects data from the field. This data is stored as text files, and I manually lump the files together and organize them. The current format is through a csv file per year per logger. Each file is around 4,000,000 lines x 7 loggers x 5 years = a lot of data. some of the data is organized as bins item_type, item_class, item_dimension_class, and other data is more unique, such as item_weight, item_color, date_collected, and so on ... Currently, I do statistical analysis on the data using a python/numpy/matplotlib program I wrote. It works fine, but the problem is, I'm the only one who can use it, since it and the data live on my computer. I'd like to publish the data on the web using a postgres db; however, I need to find or implement a statistical tool that'll take a large postgres table, and return statistical results within an adequate time frame. I'm not familiar with python for the web; however, I'm proficient with PHP on the web side, and python on the offline side. users should be allowed to create their own histograms, data analysis. For example, a user can search for all items that are blue shipped between week x and week y, while another user can search for sort the weight distribution of all items by hour for all year long. I was thinking of creating and indexing my own statistical tools, or automate the process somehow to emulate most queries. This seemed inefficient. I'm looking forward to hearing your ideas Thanks

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Tabbed application troubles in xcode

- by trludt

I am working with my first tabbed application in xcode. I am just testing with some stuff since I'm relatively new to programming. I am just using the 2 views already put into the template. I am putting a slider into the first view and am going to attach it to a text box with numbers. But that isn't the problem! This is probably really stupid and simple, but when i run the application just to see the stuff on the simulator, it is just showing a black screen. NO CLUE WHY! But its killing me and would love some help!

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Most proper way to use inherited classes with shared scopes in Mongo?

- by Trip

I have the TestVisual class that is inherited by the Game class : class TestVisual < Game include MongoMapper::Document end class Game include MongoMapper::Document belongs_to :maestra key :incorrect, Integer key :correct, Integer key :time_to_complete, Integer key :maestra_id, ObjectId timestamps! end As you can see it belongs to Maestra. So I can do Maestra.first.games But I can not to Maestra.first.test_visuals Since I'm working specifically with TestVisuals, that is ideally what I would like to pull. Is this possible with Mongo. If it isn't or if it isn't necessary, is there any other better way to reach the TestVisual object from Maestra and still have it inherit Game ?

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How cast in c#/.net 3.5 works? for types with '?'

- by Inez

This is my code which works public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : (decimal?) null; } and this one doesn't work public decimal? Get() { var res = ... return res.Count() > 0 ? res.First() : null; } giving the compilator error: Error 1 Type of conditional expression cannot be determined because there is no implicit conversion between 'decimal' and '' I wonder why? any ideas?

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How to retrieve the location of a control on the view?

- by amok

I have a button on a view, I want to add another button next to it when the first button is touched. Therefore I need it's top left corner to do the math. Here's what is puzzling me greatly: // this code is executed when the button is pressed NSLog(@"X:%f",moreButton.frame.origin.x); that returns on the first and second click the followings: 2010-04-24 22:58:25.883 iPad PopOver[8095:40b] X:-1.999002 2010-04-24 22:58:25.884 iPad PopOver[8095:40b] Y:0.000000 why and how can I get the x,y of an existing button on the view? (button created via IB) Thanks! mE ps: I have looked at similar posts and my code looks fine but I keep getting zeros (it's an ipad app if matters in any way)

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Difference in displaying inner div between IE and Chrome

- by Gaara

I have this code that has one "outerDIV" that contains an "innerDIV". On chrome the "innerDIV" size is 491px, whereas on IE it is 425px (same as outerDIV). Hence, on Chrome I can see the first two children of "innerdiv": "My test string #1" and "test2". But for IE I can only see the first child. I am not quite sure what the "right" behavior should be, as firefox does the same as IE. However I would like to have IE do the same as Chrome. I have been experimenting with some css styles (mainly overflow and display), but still can't make it right: IE will expand its height instead of its width to make the elements fit. Can you guys help me figure out a way to change the css so that IE will wraps the div elements inline? As a restriction though, I cannot change the width on the HTML. As a benefit, I am using a css that only loads for IE to patch these kind of IE inconsistencies. The same css will NOT load for chrome, so I don't need to worry about messing with chrome when changing the IE CSS. Thanks in advance! <html> <head> <style type="text/css">  </style> </head> <body> <div id="outerDIV" class="myContainer" style="display: block; width: 425px;"> <div id="innerDIV"> <div class="item"> --------My test string #1-------- </div> <div class="item"> ------test2------- </div> <div class="item"> test </div> </div> </div> </body> </html>

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Django. default=datetime.now() problem

- by Shamanu4

Hello. I've such db model: from datetime import datetime class TermPayment(models.Model): dev_session = models.ForeignKey(DeviceSession, related_name='payments') user_session = models.ForeignKey(UserSession, related_name='payment') date = models.DateTimeField(default=datetime.now(),blank=True) sum = models.FloatField(default=0) cnt = models.IntegerField(default=0) class Meta: db_table = 'term_payments' ordering = ['-date'] and here new instance is added: # ... tp = TermPayment() tp.dev_session = self.conn.session # device session hash tp.user_session = self.session # user session hash tp.sum = sum tp.cnt = cnt tp.save() But i've a problem: all records in database have the same value in date field - the date of the first payment. After server restart - one record have new date and others have the same as first after restart. It's look like some data cache is using but I can't found where. database: mysql 5.1.25 django v1.1.1

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schedule task with spring mvc

- by user3586352

I want to run the following method every specific time in spring mvc project it works fine and print first output but it doesn't access the database so it doesn't display list the method public class ScheduleService { @Autowired private UserDetailService userDetailService; public void performService() throws IOException { System.out.println("first output"); List<UserDetail> list=userDetailService.getAll(); System.out.println(list); } config file  <task:scheduled-tasks scheduler="taskScheduler"> <task:scheduled ref="ScheduleService" method="performService" fixed-delay="2000"/> </task:scheduled-tasks>  <bean id="ScheduleService" class="com.ctbllc.ctb.scheduling.ScheduleService" />  <task:scheduler id="taskScheduler" pool-size="1"/>

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- by turingcomplete

- by M.H

- by deb

- by BoltClock

- by PeanutsMonkey

- by zack_falcon

- by Akshay

- by froadie

- by James

- by kitsched

- by user333831

- by Olli

- by Robert

- by Fuangwith S.

- by Swards

- by Lee

- by RhymesWithDuck

- by dassouki

- by trludt

- by Trip

- by Inez

- by amok

- by Gaara

- by Shamanu4

- by user3586352

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