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  • Why is my number being rounded incorrectly?

    - by izb
    This feels like the kind of code that only fails in-situ, but I will attempt to adapt it into a code snippet that represents what I'm seeing. float f = myFloat * myConstInt; /* Where myFloat==13.45, and myConstInt==20 */ int i = (int)f; int i2 = (int)(myFloat * myConstInt); After stepping through the code, i==269, and i2==268. What's going on here to account for the difference?

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  • What was the most refreshingly honest non-technical comment you saw?

    - by DVK
    OK, so we all saw the lists of "funny" or "bad" comments. However, today, when maintaining an old stored procedure, I stumbled upon a comment which I couldn't classify other than "refreshingly brutally honest", left by a previous maintainer around a really freakish (both performance and readability-wise) page-long query: -- Feel free to optimize this if you can understand what it means So, in the first (and hopefully only) poll type question in my history of Stack Overflow, I'd like to hear some other "refreshingly brutally honest" code comments you encountered or written.

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  • JavaScript Object literal notation confusion

    - by Ding
    In Firefox console, this code will generate error: {"d" : ["bankaccountnumber", "$1234.56"] } SyntaxError: invalid label { message="invalid label", more...} this code works just fine {d : ["bankaccountnumber", "$1234.56"] } ["bankaccountnumber", "$1234.56"] this code works fine as well var act = {'d' : ["bankaccountnumber", "$1234.56"] } a.d Can someone help to explain why is the diference? thanks!

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  • NSAutoreleasePool carrying across methods?

    - by Tim
    I'm building an iPhone application where I detach some threads to do long-running work in the background so as not to hang the UI. I understand that threads need NSAutoreleasePool instances for memory management. What I'm not sure about is if the threaded method calls another method - does that method also need an NSAutoreleasePool? Example code: - (void)primaryMethod { [self performSelectorInBackground:@selector(threadedMethod) withObject:nil]; } - (void)threadedMethod { NSAutoreleasePool *aPool = [[NSAutoreleasePool alloc] init]; // Some code here [self anotherMethod]; // Maybe more code here [aPool drain]; } - (void)anotherMethod { // More code here } The reason I ask is I'm receiving errors that objects are being autoreleased with no pool in place, and are "just leaking." I've seen other questions where people didn't have autorelease pools in place at all, and I understand why an autorelease pool is needed. I'm specifically interested in finding out whether an autorelease pool created in (in this example) threadedMethod applies to objects created in anotherMethod.

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  • cpu floating operations cost

    - by wiso
    I'm interesting in the time cost on a modern desktop cpu of some floating point operations in order to optimize a mathematical evaluation. In particular I'm interested on the comparison between complex operations like exp, log and simple operation like +, *, /. I tried to search for these information, but I can't find a source.

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  • Just a small problem regarding javscript BOM question

    - by caramel1991
    The question is this: Create a page with a number of links. Then write code that fires on the window onload event, displaying the href of each of the links on the page. And this is my solution <html> <body language="Javascript" onload="displayLink()"> <a href="http://www.google.com/">First link</a> <a href="http://www.yahoo.com/">Second link</a> <a href="http://www.msn.com/">Third link</a> <script type="text/javascript" language="Javascript"> function displayLink() { for(var i = 0;document.links[i];i++) { alert(document.links[i].href); } } </script> </body> </html> This is the answer provided by the book <html> <head> <script language=”JavaScript” type=”text/javascript”> function displayLinks() { var linksCounter; for (linksCounter = 0; linksCounter < document.links.length; linksCounter++) { alert(document.links[linksCounter].href); } } </script> </head> <body onload=”displayLinks()”> <A href=”link0.htm” >Link 0</A> <A href=”link1.htm”>Link 2</A> <A href=”link2.htm”>Link 2</A> </body> </html> Before I get into the javascript tutorial on how to check user browser version or model,I was using the same method as the example,by acessing the length property of the links array for the loop,but after I read through the tutorial,I find out that I can also use this alternative ways,by using the method that the test condition will evalute to true only if the document.links[i] return a valid value,so does my code is written using the valid method??If it's not,any comment regarding how to write a better code??Correct me if I'm wrong,I heard some of the people say "a good code is not evaluate solely on whether it works or not,but in terms of speed,the ability to comprehend the code,and could posssibly let others to understand the code easily".Is is true??

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  • Slow MySQL query....only sometimes

    - by Shane N
    I have a query that's used in a reporting system of ours that sometimes runs quicker than a second, and other times takes 1 to 10 minutes to run. Here's the entry from the slow query log: # Query_time: 543 Lock_time: 0 Rows_sent: 0 Rows_examined: 124948974 use statsdb; SELECT count(distinct Visits.visitorid) as 'uniques' FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime>=1275721200 and visittime<=1275807599 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9 AND Visits.visitorid NOT IN (SELECT Visits.visitorid FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime<1275721200 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9); It's basically counting unique visitors, and it's doing that by counting the visitors for today and then substracting those that have been here before. If you know of a better way to do this, let me know. I just don't understand why sometimes it can be so quick, and other times takes so long - even with the same exact query under the same server load. Here's the EXPLAIN on this query. As you can see it's using the indexes I've set up: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY Visits range visittime_visitorid,visitorid visittime_visitorid 4 NULL 82500 Using where; Using index 1 PRIMARY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where 2 DEPENDENT SUBQUERY Visits ref visittime_visitorid,visitorid visitorid 8 func 1 Using where 2 DEPENDENT SUBQUERY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where I tried to optimize the query a few weeks ago and came up with a variation that consistently took about 2 seconds, but in practice it ended up taking more time since 90% of the time the old query returned much quicker. Two seconds per query is too long because we are calling the query up to 50 times per page load, with different time periods. Could the quick behavior be due to the query being saved in the query cache? I tried running 'RESET QUERY CACHE' and 'FLUSH TABLES' between my benchmark tests and I was still getting quick results most of the time. Note: last night while running the query I got an error: Unable to save result set. My initial research shows that may be due to a corrupt table that needs repair. Could this be the reason for the behavior I'm seeing? In case you want server info: Accessing via PHP 4.4.4 MySQL 4.1.22 All tables are InnoDB We run optimize table on all tables weekly The sum of both the tables used in the query is 500 MB MySQL config: key_buffer = 350M max_allowed_packet = 16M thread_stack = 128K sort_buffer = 14M read_buffer = 1M bulk_insert_buffer_size = 400M set-variable = max_connections=150 query_cache_limit = 1048576 query_cache_size = 50777216 query_cache_type = 1 tmp_table_size = 203554432 table_cache = 120 thread_cache_size = 4 wait_timeout = 28800 skip-external-locking innodb_file_per_table innodb_buffer_pool_size = 3512M innodb_log_file_size=100M innodb_log_buffer_size=4M

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  • select all values from a dimension for which there are facts in all other dimensions

    - by ideasculptor
    I've tried to simplify for the purposes of asking this question. Hopefully, this will be comprehensible. Basically, I have a fact table with a time dimension, another dimension, and a hierarchical dimension. For the purposes of the question, let's assume the hierarchical dimension is zip code and state. The other dimension is just descriptive. Let's call it 'customer' Let's assume there are 50 customers. I need to find the set of states for which there is at least one zip code in which EVERY customer has at least one fact row for each day in the time dimension. If a zip code has only 49 customers, I don't care about it. If even one of the 50 customers doesn't have a value for even 1 day in a zip code, I don't care about it. Finally, I also need to know which zip codes qualified the state for selection. Note, there is no requirement that every zip code have a full data set - only that at least one zip code does. I don't mind making multiple queries and doing some processing on the client side. This is a dataset that only needs to be generated once per day and can be cached. I don't even see a particularly clean way to do it with multiple queries short of simply brute-force iteration, and there are a heck of a lot of 'zip codes' in the data set (not actually zip codes, but the there are approximately 100,000 entries in the lower level of the hierarchy and several hundred in the top level, so zipcode-state is a reasonable analogy)

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  • Global variables in Javascript across multiple files

    - by Goro
    Hello, A bunch of my JavaScript code is in an external file called helpers.js. Inside the HTML that calls this JavaScript code I find myself in need of knowing if a certain function from helpers.js has been called. I have attempted to create a global variable by defining: var myFunctionTag = true; In global scope both in my HTML code and in helpers.js. Heres what my html code looks like: <html> ... <script type='text/javascript' src='js/helpers.js'></script> ... <script> var myFunctionTag = false; ... //I try to use myFunctionTag here but it is always false, even though it has been se t to 'true' in helpers.js </script> Is what I am trying to do even doable? Thanks,

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  • Selecting and Copying a Random File Several Times

    - by user1252778
    [Edit: see below for final code] I have the following code and I'm trying to figure out where to insert the random.choice code to make it select a single file, copy it, and repeat (here 6 times). import os import shutil import random dir_input = str(input("Enter Source Directory: ")) src_files = (os.listdir(dir_input)) for x in range (0,5): print ('This is the %d time' % x) for file_name in src_files: full_file_name = (os.path.join(dir_input, file_name)) if (os.path.isfile(full_file_name)): print ('copying...' + full_file_name) shutil.copy(full_file_name, r'C:\Dir')) else: print ('Finished!')

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  • How do Ruby and Python implement their interactive consoles?

    - by sxa
    When implementing the interpreter for my programming language I first thought of a simple console window which allows the user to enter some code which is then executed as a standalone program as a shell. But there are severe problems: If every line of code the user enters is handled as a standalone program, it has to go through the tokenizer and parser and is then just executed by the interpreter - what about functions then? How can the Python/Ruby interactive consoles (IDLE, irb) "share" the code? How is the code entered handled? Example: >> def x: >> print("Blah") >> >> x() Where is the function stored so it can be called at any time again? How can the interactive console take everything entered as obviously one program without executing everything over and over again?

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  • alternative to check, whether a value is in a set

    - by stanleyxu2005
    Hi All, I have the following code. It looks ugly, if the value equals to one of the following value then do something. var Value: Word; begin Value := 30000; if (Value = 30000) or (Value = 40000) or (Value = 1) then do_something; end; I want to refactor the code as follows: var Value: Word; begin Value := 30000; if (Value in [1, 30000, 40000]) then // Does not work do_something; end; However, the refactored code does not work. I assume that a valid set in Delphi accepts only elements with type byte. If there any good alternative to refactor my original code (besides using case)?

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  • Run time Debugging

    - by Prakash
    We have recently downloaded, installed and compiled gcc-3.0.4 code. gcc compiler has built successfully and we where able to compile some same test cpp file. I would like to know how we can modify gcc source code so that we add additional run time debugging statements like the binary in execution compiled by my gcc should print below statement in a log file: filename.cpp::FunctionName#linenumber-statement or any additional information that I can insert via this tailored compiler code Any references would be highly appreciable.

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  • how to aggregate this data in R

    - by stevejb
    Hello, I have a data frame in R with the following structure. > testData date exch.code comm.code oi 1 1997-12-30 CBT 1 468710 2 1997-12-23 CBT 1 457165 3 1997-12-19 CBT 1 461520 4 1997-12-16 CBT 1 444190 5 1997-12-09 CBT 1 446190 6 1997-12-02 CBT 1 443085 .... 77827 2004-10-26 NYME 967 10038 77828 2004-10-19 NYME 967 9910 77829 2004-10-12 NYME 967 10195 77830 2004-09-28 NYME 967 9970 77831 2004-08-31 NYME 967 9155 77832 2004-08-24 NYME 967 8655 What I want to do is produce a table the shows for a given date and commodity the total oi across every exchange code. So, the rows would be made up of unique(testData$date) and the columns would be unique(testData$comm.code) and each cell would be the total oi over all exch.codes on a given day. Thanks,

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  • php preg_replace, regexp

    - by Michael
    I'm trying to extract the postal codes from yell.com using php and preg_replace. I successfully extracted the postal code but only along with the address. Here is an example $URL = "http://www.yell.com/ucs/UcsSearchAction.do?scrambleSeed=17824062&keywords=shop&layout=&companyName=&location=London&searchType=advance&broaderLocation=&clarifyIndex=0&clarifyOptions=CLOTHES+SHOPS|CLOTHES+SHOPS+-+LADIES|&ooa=&M=&ssm=1&lCOption32=RES|CLOTHES+SHOPS+-+LADIES&bandedclarifyResults=1"; //get yell.com page in a string $htmlContent = $baseClass-getContent($URL); //get postal code along with the address $result2 = preg_match_all("/(.*)/", $htmlContent, $matches); print_r($matches); The above code ouputs something like Array ( [0] = Array ( [0] = 7, Royal Parade, Chislehurst, Kent BR7 6NR [1] = 55, Monmouth St, London, WC2H 9DG .... the problem that I have is that I don't know how to extract the the postal code because it doesn't have an exact number of digits (sometimes it has 6 digits and sometimes has only 5 times). Basically I should extract the lasted 2 words from each array . Thank you in advance for any help !

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  • Converting an empty string into nil in Ruby

    - by adi92
    I have a string called word and a function called infinitive such that word.infinitive would return another string on some occasions and an empty string otherwise I am trying to find an elegant ruby one line expression for the code-snippet below if word.infinitive == "" return word else return word.infinitive Had infinitive returned nil instead of "", I could have done something like (word.infinitive or word) But since it does not, I can't take advantage of the short-circuit OR Ideally I would want 1) a single expression that I could easily embed in other code 2) the function infinitive being called only once 3) to not add any custom gems or plugins into my code

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  • Getting the first of a GROUP BY clause in SQL

    - by Michael Bleigh
    I'm trying to implement single-column regionalization for a Rails application and I'm running into some major headaches with a complex SQL need. For this system, a region can be represented by a country code (e.g. us) a continent code that is uppercase (e.g. NA) or it can be NULL indicating the "default" information. I need to group these items by some relevant information such as a foreign key (we'll call it external_id). Given a country and its continent, I need to be able to select only the most specific region available. So if records exist with the country code, I select them. If, not I want a records with the continent code. If not that, I want records with a NULL code so I can receive the default values. So far I've figured that I may be able to use a generated CASE statement to get an arbitrary sort order. Something like this: SELECT *, CASE region WHEN 'us' THEN 1 WHEN 'NA' THEN 2 ELSE 3 END AS region_sort FROM my_table WHERE region IN ('us','NA') OR region IS NULL GROUP BY external_id ORDER BY region_sort The problem is that without an aggregate function the actual data returned by the GROUP BY for a given row seems to be untameable. How can I massage this query to make it return only the first record of the region_sort ordered groups?

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  • Overriding fetch in multiple spine models

    - by Adam Charnock
    I need to override Spine's @fetch() method in all of my Spine models. Currently I have code duplication as follows: TastypieEndpointMixin = fromJSON: (data) -> return unless data return Spine.Model.fromJSON(data.objects) class App.models.Position extends Spine.Model @configure 'Position', 'code', 'name' @extend Spine.Model.Ajax @extend TastypieEndpointMixin @url: '/api/v1/position/?format=json' validate: -> 'code is required' unless @code @fetch: -> defer = $.Deferred() @one "refresh", -> defer.resolve() super return defer class App.models.Player extends Spine.Model @configure 'Player', 'first_name', 'last_name', ... @extend Spine.Model.Ajax @extend TastypieEndpointMixin @url: '/api/v1/player/?format=json' @fetch: -> defer = $.Deferred() @one "refresh", -> defer.resolve() super return defer My question is: How can I create some form of parent class which contains @fetch()? I know this should be a simple problem to solve. I have tried many options (including extending Spine.Model and Spine.Model.Ajax), but nothing works and I cannot seem to get my head around it.

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  • Save image in Windows Mobile 5.0 using C#

    - by Vijay V
    Hi I am saving image in windows mobile application using C#.My code is SaveFileDialog dialog = new SaveFileDialog(); if (dialog.ShowDialog() == DialogResult.OK) { aspectRatioPictureBox1.Photo.Save(dialog.FileName, System.Drawing.Imaging.ImageFormat.Bmp); } In the above code i am able to save only in folders of MyDocument But i am not able to browse to save in other folders.. Please let know the code to save image through browsing the location Thanks in Advance

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  • formatting sourcecode using jQuery

    - by Sorskoot
    Does anyone know if there's a jQuery plugin to format code, XML or HTML? I'm showing the user some code on an html page. I used google prettify to make the code look pretty, but would like some indentation and linebreaks too. any suggestions?

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  • Upgrading From EF 4x to 6 breaks everything

    - by dan h
    Attempted to upgrade my project from EF4 to EF6, I get build errors It appears that if i swap out the namespaces manually to include the entity.core it works, but if i change the .edmx file at all, the code reverts back to the old references and i have to manually edit the code generation files to include the update namespace references. I have attempted to "add code generation item" that does not resolve the issue at all. When i open the .edmx file in the IDE it shows me everything correctly.

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