Search Results

Search found 11015 results on 441 pages for 'explain plan'.

Page 291/441 | < Previous Page | 287 288 289 290 291 292 293 294 295 296 297 298  | Next Page >

• PropelBundle database:create for postgres

  - by Karol85

  I've installed propel bundle for symfony2. my database configuration is: propel: dbal: driver: pgsql user: postgres password: postgres dsn: pgsql:host=localhost;port=5432;dbname=test_database options: {} attributes: {} When i wan to create this database from console (console propel: database:create) i have got strange error : Unable to open PDO connection [wrapped: SQLSTATE[08006] [7] FATAL: database "pgsql" does not exist. i created pgsql database on my localhost and everything was good. Database "test_database" was succesfull created. Can somebody explain me why i got this previous error? On mysql i've created database without any problems.

  Read the article

• Hebbian learning

  - by Bane

  I have asked another question on Hebbian learning before, and I guess I got a good answer which I accepted, but, the problem is that I now realize that I've mistaken about Hebbian learning completely, and that I'm a bit confused. So, could you please explain how it can be useful, and what for? Because the way Wikipedia and some other pages describe it - it doesn't make sense! Why would we want to keep increasing the weight between the input and the output neuron if the fire together? What kind of problems can it be used to solve, because when I simulate it in my head, it certainly can't do the basic AND, OR, and other operations (say you initialize the weights at zero, the output neurons never fire, and the weights are never increased!)

  Read the article

• What exactly does it mean when $_FILES is empty?

  - by Mike

  I am working on an upload script and when testing my error checks, I attempted to upload a 17MB TIFF file. When I do this the $_FILES array is empty. The script works fine for what I need it to do, which is to upload JPEG files. My solution is to test if $_FILES is empty or not before continuing with the upload script. Can anybody explain why $_FILES is empty when a TIFF is attempted to be uploaded? Is my solution, to check if $_FILES is empty or not, an okay one?

  Read the article

• Explanation needed for sum of prime below n numbers

  - by Bala Krishnan

  Today I solved a problem given in Project Euler its problem no 10 and it took 7 hrs for my python program to show the result. But in that forum itself a person named lassevk posted solution for this and it took only 4 sec. And its not possible for me to post this question in that forum because its not discussion forum. So, think about this if you want to mark this question as non-constructive. marked = [0] * 2000000 value = 3 s = 2 while value < 2000000: if marked[value] == 0: s += value i = value while i < 2000000: marked[i] = 1 i += value value += 2 print s If any one understand this code please explain it simple as possible. Link to the Problem 10 question.

  Read the article

• does adding static library need xcode project of static library for linking?

  - by mirdad

  I have seen some static library projects in iOS.I see two different types of linking static library. 1)adding .a static library to new xcode project and its header files only. 2)adding .a static library to new xcode project and adding the xcode project through which static library has created. when I remove the the xcode project through which static library has created from the 2nd project, it gives error.I tried first approach for 2nd one.But it is not working. Can you please explain why it is differed? Will it be differed by the xcode versions we use? is The second approach for old xcode versions?

  Read the article

• Lucene .NET IndexWriter lock

  - by Pini Salim

  My question related to the next code snippet: static void Main(string[] args) { Lucene.Net.Store.Directory d = FSDirectory.Open(new DirectoryInfo(/*my index path*/)); IndexWriter writer = new IndexWriter(d, new WhitespaceAnalyzer()); //Exiting without closing the indexd writer... } In this test, I opened an IndexWriter without closing it - so even after the test exits, the write.lock file still exists in the index directory, so I expected that the next time I open an instance of IndexWriter to that index, a LockObatinFailedException will be thrown. Can someone please explain to me why am I wrong? I mean, does the meaning of the write.lock file is to protect creation of two IndexWriters in the same process only? that doesnt seems the right answer to me...

  Read the article

• Analyzing Python Code: Modulus Operator

  - by Bhubhu Hbuhdbus

  I was looking at some code in Python (I know nothing about Python) and I came across this portion: def do_req(body): global host, req data = "" s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, 80)) s.sendall(req % (len(body), body)) tmpdata = s.recv(8192) while len(tmpdata) > 0: data += tmpdata tmpdata = s.recv(8192) s.close() return data This is then called later on with body of huge size, as in over 500,000 bytes. This is sent to an Apache server that has the max request size on the default 8190 bytes. My question is what is happening at the "s.sendall()" part? Obviously the entire body cannot be sent at once and I'm guessing it is reduced by way of the modulus operator. I don't know how it works in Python, though. Can anyone explain? Thanks.

  Read the article

• SQL statement HAVING MAX(some+thing)=some+thing

  - by Andreas

  I'm having trouble with Microsoft Access 2003, it's complaining about this statement: select cardnr from change where year(date)<2009 group by cardnr having max(time+date) = (time+date) and cardto='VIP' What I want to do is, for every distinct cardnr in the table change, to find the row with the latest (time+date) that is before year 2009, and then just select the rows with cardto='VIP'. This validator says it's OK, Access says it's not OK. This is the message I get: "you tried to execute a query that does not include the specified expression 'max(time+date)=time+date and cardto='VIP' and cardnr=' as part of an aggregate function." Could someone please explain what I'm doing wrong and the right way to do it? Thanks

  Read the article

• Why does concatenating a boolean value return an integer?

  - by joshhunt

  In python, you can concatenate boolean values, and it would return an integer. Example: >>> True True >>> True + True 2 >>> True + False 1 >>> True + True + True 3 >>> True + True + False 2 >>> False + False 0 Why? Why does this make sense? I understand that True is often represented as 1, whereas False is represented as 0, but that still does not explain how adding two values together of the same type returns a completely different type.

  Read the article

• A simple group-by (no count) in Django

  - by Daniel Quinn

  If this were raw-SQL, it'd be a no-brainer, but in Django, this is proving to be quite difficult to find. What I want is this really: SELECT user_id FROM django_comments WHERE content_type_id = ? AND object_pk = ? GROUP BY user_id It's those last two lines that're the problem. I'd like to do this the "Django-way" but the only thing I've found is mention of aggregates and annotations, which I don't think solve this issue... do they? If someone could explain this to me, I'd really appreciate it.

  Read the article

• CSS: How to affect OTHER elements when a div is hovered

  - by Trufa

  I think this is a very basic question but I not sure how/if it can be done. What I want to do is to is a certain div is hovered, affect the properties of another div. For example, in this simple example when you hover over #cube it changes the background-color but what I that when I hover over #container, #cubeis affected. I don't want to explain further cause I think it might be confusing, but please ask the the question is no clear enough!! Thanks in advance!! jQueriers: abstain yourselves!! only CSS answers :)

  Read the article

• Purpose of Instance Methods vs. Class Methods in Objective-C

  - by qegal

  I have checked out all these questions... Difference Class and Instance Methods Difference between class methods and instance methods? Objective-C: Class vs Instance Methods? ...and all they explain is how instance methods are used on instances of a class and class methods are used with the class name, when a message is sent to a class object. This is helpful, but I'm curious to know why one would use a class method vs. an instance method. I'm fairly new to iOS application development, and usually use class methods, and I feel like I'm doing something wrong. Thanks in advanced!

  Read the article

• What do you do when you feel you need a variadic list comprehension?

  - by cspyr0

  I would like to make a method where I could give it a list of lengths and it would return all combinations of cartesian coordinates up to those lengths. Easier to explain with an example: cart [2,5] Prelude> [ [0,0],[0,1],[0,2],[0,3],[0,4],[1,0],[1,1],[1,2],[1,3],[1,4] ] cart [2,2,2] Prelude> [ [0,0,0],[0,0,1],[0,1,0],[0,1,1],[1,0,0],[1,0,1],[1,1,0],[1,1,1] ] A simple list comprehension won't work because I don't know how long the lists are going to be. While I love Haskell's simplicity for many problems, this is one that I could write procedurally (in C or something) in 5 minutes whereas Haskell gives me an aneurysm! A solution to this specific problem would help me out a lot; I'd also love to hear about your thought processes when tackling stuff like this.

  Read the article

• Do you have to create a View Controller to move between views?

  - by Frames84

  I want a single startup view with a button and a welcome screen. When the button is pressed I then want to navigate to a second view which contains a table view and toolbar. I've tried creating a ViewController but my button is shown on all views. I just want a single view, then when it's pressed i go to the next view and the 'real' app starts. Can someone please try and explain the best architecture to do this? (like in chapter 6 of beginning iPhone 3 Development by Dave Mark and Jeff LaMarche ) Thanks

  Read the article

• Custom components vs default components in GUI Design. Which is more practical? (.NET)

  - by AlexRednic

  Ok, so is it better to create my own components (Either inherit them from existing ones or creating them from scratch) or to use the ones that come by default? I'm asking this under the umbrella of scalability, overhead and other factors that my contribute on each of the choices. UPDATE: Sorry if I'm to vague. I don't really know how to explain myself better. Isn't it a good idea to inherit each default component? For example what if I'm to design a rather large application and for example i need to change the display format on a DateTimePicker. Wouldn't it better to think ahead and inherit it and use the inherited component instead of the defaults? But, wouldn't it add a lot of overhead in small applications?

  Read the article

• functions in F# .. why is it not compiling

  - by Tanmoy

  Hi, I have written two versions of code. The first one works as expected and print "Hi". the second one gives me error that "block following this let is unfinished" 1st version #light let samplefn() = let z = 2 let z = z * 2 printfn "hi" samplefn() 2nd version #light let samplefn() = let z = 2 let z = z * 2 samplefn() Only difference is the printfn is absent in the second version. I am using Visual Studio 2010 as my IDE. I am very new to F# but this error seems very strange to me. I guess I am missing some very important concept. Please explain. Edit: Also if I do it outside the function I get error even with the first version of code. #light let z = 2 let z = z * 2 printfn "Error: Duplicate definition of value z"

  Read the article

• How to find scrollable elements in DOM using XPath?

  - by ak.

  Basically I need to find all elements on the page that have a scrollbar (vertical or horizontal) How to tell if an element has a scrollbar and can actually be scrolled? I found this code snippet on jsperf. Is it possible to capture the logic behind the code into and XPath expression? Or are there any other ways to check for scrollbars? Added: Just to explain what I'm trying to do: I'm developing extension for Firefox. Basically it introduces Vim-style mouseless shortcuts (I know there is Vimperator and Pentadactyl...). One of the features I'd like to implement is to allow the use to select the container that's scrolled with j/k keys. That's why I need to discover all scrollable elements on any given random page.

  Read the article

• segmentation fault

  - by gcc

  int num_arrays; char *p[20]; char tempc; int i=0; do { p[i]=malloc(sizeof(int)); scanf("%s",p[i]); tempc=p[i]; ++i; }while(tempc=='x'); num_arrays=atoi(p[0]); When i write num_arrays=atoi(..),gcc give me segmentation fault or memory stack is exceeded, I don't understand why it behaves like that can anyone explain, why?

  Read the article

• Deriving PathInfo class in web routes?

  - by drozzy

  I am reading the web-routes tutorial in Happstack, and I have no idea what this is doing: $(derivePathInfo ''Sitemap) class PathInfo a where toPathSegments :: a -> [String] fromPathSegments :: URLParser a The doc simply says: we use template-haskell to derive an instance of PathInfo for the Sitemap type. but where does it "store" it? I thought haskell had no state, and is PathInfo our own thing, or is it part of happstack? If someone could explain this, for dummies? Thanks.

  Read the article

• typedef declaration syntax

  - by mt_serg

  Some days ago I looked at boost sources and found interesting typedef. There is a code from "boost\detail\none_t.hpp": namespace boost { namespace detail { struct none_helper{}; typedef int none_helper::*none_t ; } // namespace detail } // namespace boost I didn't see syntax like that earlier and can't explain the sense of that. This typedef introduces name "none_t" as pointer to int in boost::detail namespace. What the syntax is? And what difference between "typedef int none_helper::*none_t" and for example "typedef int *none_t" ?

  Read the article

• Different behaviour of browsers while caching the same file.

  - by Amrita

  I am trying to implement mod_disk_caching. i wrote a php code as shown in the example of the tutorial i was following. i fired the following in the terminal a2enmod cache a2enmod disk_cache /etc/init.d/apache2 force-reload then in the php code "; ? now i tried running it using firefox. In the first execution i got the following timestamp. 1308643975 here, when i press refresh, the timestamp changes (as the file is reloaded from the server) and remains the same when i click the link again (as the file is retrieved from the cache). Now i am trying the same with IExplorer. As per my understanding, the timestamp should be the same as the subsequent request for the file will be retrieved only from the cache. But i got a different timestamp. Can anyone explain me the reason for this? Why is it giving separate timestamps when the browsers are different? Thanks and Regards, AMJ

  Read the article

• Objective C for Windows

  - by Luther Baker

  What would be the best way to write Objective-C on the Windows platform? Cygwin and gcc? Is there a way I can somehow integrate this into Visual Studio? Along those lines - are there any suggestions as to how to link in and use the Windows SDK for something like this. Its a different beast but I know I can write assembly and link in the Windows DLLs giving me accessibility to those calls but I don't know how to do this without googling and getting piecemeal directions. Is anyone aware of a good online or book resource to do or explain these kinds of things?

  Read the article

• Choosing the right and learning assembler for compiler-writing

  - by X A

  I'm writing a compiler and I have gone through all the steps (tokenizing, parsing, syntax tree structures, etc.) that they show you in all the compiler books. (Please don't comment with the link to the "Resources for writing a compiler" question!). I have chosen to use NASM together with alink as my backend. Now my problem is: I just can't find any good resources for learning NASM and assembly in general. The wikibook (german) on x86 assembly is horrible. They don't even explain the code they write there, I currently can't even get simple things like adding 1 to 2 and outputting the result working. Where can I learn NASM x86 assembly?

  Read the article

• How do I use a UIView subclass as a container?

  - by dxq

  I'm trying to subclass UIView to create a custom view that is essentially a container. The subclass contains a UILabel and a UIImageView- I can't make either of them show up. Here's an example of what I've been trying: In my main view controller: - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { ViewClass *myView = [[ViewClass alloc] initWithFrame:CGRectMake(100, 100, 150, 150)]; [view addSubview:myView]; } return self; } In my UIView subclass: - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { UILabel *word = [[[UILabel alloc] initWithFrame:[self bounds]] autorelease]; word.text = @"WHY ISN'T THIS SHOWING UP!?"; [self addSubview:word]; } return self; } Can anyone explain what I'm doing wrong? I'm way out of practice with UIKit and Obj-C, and I figure I'm probably missing something obvious.

  Read the article

• How to execute a large PHP Script ?

  - by atif089

  Well basically I may want to execute a script that may take as much as 1 hours as well. What I really want to do is Send SMS to my users using a third party API. So its basically like I supply my script with an array of phone numbers and fire the method to send SMS. However assuming it take 5 seconds to send 1 SMS and I want to send 1000 SMS which is roughly 1 - 2 hours. I can use set_time_limit() because I am on shared host. One way to do this is store numbers in a session and execute each SMS and use javascript to refresh that page until end. This way I need to keep my browser open and the execution will stop if my Internet Connection is disconnected. So, Is there any better way to do this ? Hope I am clear enough to explain what I want? I want to execute a large script that may take hours to execute without getting timeout.

  Read the article

< Previous Page | 287 288 289 290 291 292 293 294 295 296 297 298  | Next Page >