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  • Can hash tables really be O(1)

    - by drawnonward
    It seems to be common knowledge that hash tables can achieve O(1) but that has never made sense to me. Can someone please explain it? A. The value is an int smaller than the size of the hash table, so the value is its own hash, so there is no hash table but if there was it would be O(1) and still be inefficient. B. You have to calculate the hash, so the order is O(n) for the size of the data being looked up. The lookup might be O(1) after you do O(n) work, but that still comes out to O(n) in my eyes. And unless you have a perfect hash or a large hash table there are probably several items per bucket so it devolves into a small linear search at some point anyway. I think hash tables are awesome, but I do not get the O(1) designation unless it is just supposed to be theoretical.

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  • Validating a phone number in Android PreferenceScreen

    - by djechelon
    I have a PreferenceScreen in which the user is capable, if system can't autodetect it, to enter the device's phone number. I'm still learning this part of Android but I managed to understand a bit of PreferenceScreens by examples provided by Android SDK itself and a few tutorials. What I want is that the user can save the phone number only if null or valid, where by "valid" I mean running a generic validation logic (ie. an anonymous method that returns true or false, that can be reused in any possible situation*) or better, just to simplify things, ^(\+39)?3[0-9]{9}$ For now I have the following XML snip <EditTextPreference android:inputType="phone" android:key="@string/preference_phoneNo" android:selectAllOnFocus="true" android:singleLine="true" android:summary="@string/pref_phoneNumber_description" android:title="@string/pref_phoneNumber" /> and following code by courtesy of Eclipse New Activity wizard: private void setupSimplePreferencesScreen() { if (!isSimplePreferences(this)) { return; } addPreferencesFromResource(R.xml.pref_general); bindPreferenceSummaryToValue(findPreference(getString(R.string.preference_phoneNo))); } addPreferenceFromResource is supposed to load the XML node and add the preference to the screen, while binPreferenceSummaryToValue is supposed to make description text change when preference is updated. Just for sake of completeness for those who don't like code courtesy of the IDE, the second method is provided by Eclipse who also provides a private class in the code file that is /** * A preference value change listener that updates the preference's summary * to reflect its new value. */ In the general case, what should I do to perform validation logic before the preference gets saved when I click OK on the preference editor? Where is the validation logic to be put in a PreferenceScreen? *Aren't we all here to learn?

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  • Adding up row number and displaying total using COUNT (PHP MySQL)

    - by Yvonne
    I'm attempting to run a query that adds up the total number of subjects in a class. A class has many subjects. There is a 'teachersclasses' table between teachers (the user table) and classes. The principles sounds pretty simple but I'm having some trouble in getting my page to display the number of subjects for each class (directly associated with the teacher) This is what I have so far, trying to make use of the COUNT with a nested SELECT: SELECT (SELECT count(*) FROM subjects WHERE subjects.classid = class.classid) AS total_subjects, class.classname, class.classid FROM class Then I am calling up 'num_subjects' to present the total within a while loop: <?php echo $row['total_subjects']?> From the above, I am receiving the total subjects for a class, but within the same table row (for one class) and my other while loop doesnt run anymore, which returns all of the classes associated with a teacher :( ... Bit of a mess now! I know to return the classes for a particular teacher, I can do an additional WHERE clause on the session of 'teacherid' but I think my query is getting too complicated for me that errors are popping up everywhere. Anyone have a quick fix for this! Thanks very much

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  • Sort vector<int>(n) in O(n) time using O(m) space?

    - by Adam
    I have a vector<unsigned int> vec of size n. Each element in vec is in the range [0, m], no duplicates, and I want to sort vec. Is it possible to do better than O(n log n) time if you're allowed to use O(m) space? In the average case m is much larger than n, in the worst case m == n. Ideally I want something O(n). I get the feeling that there's a bucket sort-ish way to do this: unsigned int aux[m]; aux[vec[i]] = i; Somehow extract the permutation and permute vec. I'm stuck on how to do 3. In my application m is on the order of 16k. However this sort is in the inner loops and accounts for a significant portion of my runtime.

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  • tight (T) bound

    - by tomwu
    Can someone explain this to me? Such as this: Given a function: for k = 1 to lg(n) for j = 1 to n x=x+1 How would I analyze the tight (T) bound?

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  • MVC HTML.RenderAction – Error: Duration must be a positive number

    - by BarDev
    On my website I want the user to have the ability to login/logout from any page. When the user select login button a modal dialog will be present to the user for him to enter in his credentials. Since login will be on every page, I thought I would create a partial view for the login and add it to the layout page. But when I did this I got the following error: Exception Details: System.InvalidOperationException: Duration must be a positive number. There are other ways to work around this that would not using partial views, but I believe this should work. So to test this, I decided to make everything simple with the following code: Created a layout page with the following code @{Html.RenderAction("_Login", "Account");} In the AccountController: public ActionResult _Login() { return PartialView("_Login"); } Partial View _Login <a id="signin">Login</a> But when I run this simple version this I still get this error: Exception Details: System.InvalidOperationException: Duration must be a positive number. Source of error points to "@{Html.RenderAction("_Login", "Account");}" There are some conversations on the web that are similar to my problem, which identifies this as bug with MVC (see links below). But the links pertain to Caching, and I'm not doing any caching. OuputCache Cache Profile does not work for child actions http://aspnet.codeplex.com/workitem/7923 Asp.Net MVC 3 Partial Page Output Caching Not Honoring Config Settings Asp.Net MVC 3 Partial Page Output Caching Not Honoring Config Settings Caching ChildActions using cache profiles won't work? Caching ChildActions using cache profiles won't work? I'm not sure if this makes a difference, but I'll go ahead and add it here. I'm using MVC 3 with Razor. Update Stack Trace [InvalidOperationException: Duration must be a positive number.] System.Web.Mvc.OutputCacheAttribute.ValidateChildActionConfiguration() +624394 System.Web.Mvc.OutputCacheAttribute.OnActionExecuting(ActionExecutingContext filterContext) +127 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) +72 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) +784922 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList1 filters, ActionDescriptor actionDescriptor, IDictionary2 parameters) +314 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +784976 System.Web.Mvc.Controller.ExecuteCore() +159 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +335 System.Web.Mvc.<c_DisplayClassb.b_5() +62 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +20 System.Web.Mvc.<c_DisplayClasse.b_d() +54 System.Web.Mvc.<c_DisplayClass4.b_3() +15 System.Web.Mvc.ServerExecuteHttpHandlerWrapper.Wrap(Func`1 func) +41 System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) +1363 [HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerAsyncWrapper'.] System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) +2419 System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage) +275 System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) +94 System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter) +838 System.Web.Mvc.Html.ChildActionExtensions.RenderAction(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues) +56 ASP._Page_Views_Shared_SiteLayout_cshtml.Execute() in c:\Projects\Odat Projects\Odat\Source\Presentation\Odat.PublicWebSite\Views\Shared\SiteLayout.cshtml:80 System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +280 System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +104 System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +173 System.Web.WebPages.WebPageBase.Write(HelperResult result) +89 System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action1 body) +234 System.Web.WebPages.WebPageBase.PopContext() +234 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +384 System.Web.Mvc.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() +33 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +784900 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +784900 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +265 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +784976 System.Web.Mvc.Controller.ExecuteCore() +159 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +335 System.Web.Mvc.<c_DisplayClassb.b_5() +62 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +20 System.Web.Mvc.<c_DisplayClasse.b_d() +54 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +453 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +371 Update When I Break in Code, it errors at @{Html.RenderAction("_Login", "Account");} with the following exception. The inner exception Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerAsyncWrapper'. at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage) at System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) at System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter) at System.Web.Mvc.Html.ChildActionExtensions.RenderAction(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues) at ASP._Page_Views_Shared_SiteLayout_cshtml.Execute() in c:\Projects\Odat Projects\Odat\Source\Presentation\Odat.PublicWebSite\Views\Shared\SiteLayout.cshtml:line 80 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.WebPages.WebPageBase.Write(HelperResult result) at System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action1 body) at System.Web.WebPages.WebPageBase.PopContext() at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) Answer Thanks Darin Dimitrov Come to find out, my AccountController had the following attribute [System.Web.Mvc.OutputCache(NoStore =true, Duration = 0, VaryByParam = "*")]. I don't believe this should caused a problem, but when I removed the attribute everything worked. BarDev

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  • Ruby number_to_currency displays a totally wrong number!

    - by SueP
    Greetings! I’m an old Delphi programmer making the leap to the Mac, Ruby, Rails, and web programming in general. I’m signed up for the Advanced Rails workshop at the end of the month. In the meantime, I’ve been working on porting a mission-critical (of course) app from Delphi to RAILS. It feels like I’ve spent most of the past year with my head buried in a book or podcast. Right now, I’ve hit a major issue and I’m tearing my hair out. I literally don’t know where to go with this, I desperately don’t want to deploy with this bug, and I’m feeling a bit frantic. (The company database is currently running on an ancient XP box that’s looking rustier by the day.) So, I set up a test database that shows the problem. I’m running: OS/X 10.6.3 Rails 2.3.5 ruby 1.8.7 (2009-06-08 patchlevel 173) [universal-darwin10.0] MySQL 5.1.38-log via socket MySQL Client Version 5.1.8 ActiveRecord::Schema.define(:version => 20100406222528) do create_table “money”, :force => true do |t| t.decimal “amount_due”, :precision => 10, :scale => 2, :default => 0.0 t.decimal “balance”, :precision => 10, :scale => 2, :default => 0.0 t.text “memofield” t.datetime “created_at” t.datetime “updated_at” end The index view is right out of the generator, slightly modified to add the formatting that's breaking on me. Listing money <table> <tr> <th>Amount</th> <th>Amount to_s </th> <th>Balance to $</th> <th>Balance with_precision </th> <th>Memofield</th> </tr> <% @money.each do |money| %> <tr> <td><%=h money.amount_due %></td> <td><%=h money.amount_due.to_s(‘F’) %></td> <td><%=h number_to_currency(money.balance) %></td> <td><%=h number_with_precision(money.balance, :precision => 2) %></td> <td><%=h money.memofield %></td> <td><%= link_to ‘Show’, money %></td> <td><%= link_to ‘Edit’, edit_money_path(money) %></td> <td><%= link_to ‘Destroy’, money, :confirm => ‘Are you sure?’, :method => :delete %></td> </tr> *<% end %> *</table> <%= link_to ‘New money’, new_money_path %> This seemed to work pretty well. Then I started testing with production data and hit a major problem with number_to_currency. The number in the database is: 10542.28, I verified it with the MySQL Query Browser. RAILS will display this as 10542.28 unless I call number_to_currency, then that number is displayed as: $15422.80 The error seems to happen with any number between 10,000.00 and 10,999.99 So far, I haven’t seen it outside of that range, but I obviously haven’t tested everything. I guess my workaround is to remove number_to_currency, but that leaves the views looking really sloppy and unprofessional. The formatting is messed up, things don’t line up properly and I can’t force the display to 2 decimal places. I’m seriously hoping there is an easy fix for this. I can’t imagine this being a widespread problem. It would affect so many people that someone would have fixed it! But I don’t know where to go from here. I’d desperately like some help. (Later – number_with_precision fails the same way number_to_currency does.) Sue Petersen

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  • Performance considerations for common SQL queries

    - by Jim Giercyk
    Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results.  There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set.  Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient.  For the queries below, I downloaded the test database from SQLSkills:  http://www.sqlskills.com/sql-server-resources/sql-server-demos/.  There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554.  Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table.   /*************/ /* Sub Query  */ /*************/ SELECT  a.[Member Number] ,         m.lastname ,         m.firstname ,         a.[Number Of Payments] ,         a.[Average Payment] ,         a.[Total Paid] FROM    ( SELECT    member_no 'Member Number' ,                     AVG(payment_amt) 'Average Payment' ,                     SUM(payment_amt) 'Total Paid' ,                     COUNT(Payment_No) 'Number Of Payments'           FROM      dbo.payment           GROUP BY  member_no           HAVING    COUNT(Payment_No) > 1         ) a         JOIN dbo.member m ON a.[Member Number] = m.member_no         /***************/ /* Cross Apply  */ /***************/ SELECT  ca.[Member Number] ,         m.lastname ,         m.firstname ,         ca.[Number Of Payments] ,         ca.[Average Payment] ,         ca.[Total Paid] FROM    dbo.member m         CROSS APPLY ( SELECT    member_no 'Member Number' ,                                 AVG(payment_amt) 'Average Payment' ,                                 SUM(payment_amt) 'Total Paid' ,                                 COUNT(Payment_No) 'Number Of Payments'                       FROM      dbo.payment                       WHERE     member_no = m.member_no                       GROUP BY  member_no                       HAVING    COUNT(Payment_No) > 1                     ) ca /********/                    /* CTEs  */ /********/ ; WITH    Payments           AS ( SELECT   member_no 'Member Number' ,                         AVG(payment_amt) 'Average Payment' ,                         SUM(payment_amt) 'Total Paid' ,                         COUNT(Payment_No) 'Number Of Payments'                FROM     dbo.payment                GROUP BY member_no                HAVING   COUNT(Payment_No) > 1              ),         MemberInfo           AS ( SELECT   p.[Member Number] ,                         m.lastname ,                         m.firstname ,                         p.[Number Of Payments] ,                         p.[Average Payment] ,                         p.[Total Paid]                FROM     dbo.member m                         JOIN Payments p ON m.member_no = p.[Member Number]              )     SELECT  *     FROM    MemberInfo /************************/ /* SELECT with Grouping   */ /************************/ SELECT  p.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         COUNT(Payment_No) 'Number Of Payments' ,         AVG(payment_amt) 'Average Payment' ,         SUM(payment_amt) 'Total Paid' FROM    dbo.payment p         JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no ,         m.lastname ,         m.firstname HAVING  COUNT(Payment_No) > 1   We can see what is going on in SQL’s brain by looking at the execution plan.  The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes.  SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan.  We can settle this once and for all.  Here is what SQL did with these queries:   Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them.  Everybody is right…..I guess we can all finally go to lunch together!  But wait a second, I may not be a fighter, but I AM an instigator.     Let’s see how a table variable stacks up.  Here is the code I executed: /********************/ /*  Table Variable  */ /********************/ DECLARE @AggregateTable TABLE     (       member_no INT ,       AveragePayment MONEY ,       TotalPaid MONEY ,       NumberOfPayments MONEY     ) INSERT  @AggregateTable         SELECT  member_no 'Member Number' ,                 AVG(payment_amt) 'Average Payment' ,                 SUM(payment_amt) 'Total Paid' ,                 COUNT(Payment_No) 'Number Of Payments'         FROM    dbo.payment         GROUP BY member_no         HAVING  COUNT(Payment_No) > 1   SELECT  at.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         at.NumberOfPayments 'Number Of Payments' ,         at.AveragePayment 'Average Payment' ,         at.TotalPaid 'Total Paid' FROM    @AggregateTable at         JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query.  Here’s what I got:     Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps.  BUT, the combination of the 2 steps is only 22% of the batch.  It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan.  The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan.  While this is true, the estimate does not come in to play until you read from the table variable.  In this case, the table variable had 6,706 rows, but it still outperformed the other queries.  People argue that table variables should only be used for hash or lookup tables.  The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results.  My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style.  If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate.  If you have a company standard, I strongly recommend you follow it.    If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule.  Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment.  Download the database and try it!

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  • Regular Expressions

    - by Rocky
    Hello Everyone, I am new to Stackoverflow and I have a quick question. Let's assume we are given a large number of HTML files (large as in theoretically infinite). How can I use Regular Expressions to extract the list of Phone Numbers from all those files? Explanation/expression will be really appreciated. The Phone numbers can be any of the following formats: (123) 456 7899 (123).456.7899 (123)-456-7899 123-456-7899 123 456 7899 1234567899 Thanks a lot for all your help and have a good one!

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  • Simple hardware RNG

    - by roygbiv
    I made a tongue-in-cheek comment to this question about making a hardware RNG. Does anyone know of any simple plans or can anyone descibe a simple hardware based RNG and the software to drive it? Go to Radio Shack. Buy a diode, an NTR resistor, a capacitor and serial cable. Cut off the end of the serial cable that does not fit on your computer. Solder the diode and resistor in series between pins DTR and DSR of the cable. Solder the capacitor between DSR and TXD pins. Write a small C program to do the following: Set DTR to 1. Start Timer. Monitor DSR until it goes to 1. Stop Timer. Calculate resistance from elapsed time. Retreive serveral bits from that value to use as part of random number. Repeat until enough bits have accumulated.

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  • Regular Expression for finding phone numbers

    - by Rocky
    Hello Everyone, I am new to Stackoverflow and I have a quick question. Let's assume we are given a large number of HTML files (large as in theoretically infinite). How can I use Regular Expressions to extract the list of Phone Numbers from all those files? Explanation/expression will be really appreciated. The Phone numbers can be any of the following formats: (123) 456 7899 (123).456.7899 (123)-456-7899 123-456-7899 123 456 7899 1234567899 Thanks a lot for all your help and have a good one!

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  • Generating random numbers in C

    - by moonstruckhorrors
    While searching for Tutorials on generating random numbers in C I found This Topic When I try to use the rand() function with parameters, I always get the random number generated 0. When I try to use the rand() function with parameters, I always get the value 41. And whenever I try to use arc4random() and random() functions, I get a LNK2019 error. Here's what I'm doing: #include <stdlib.h> int main() { int x; x = rand(6); printf("%d", x); } This code always generate 41. Where am I going wrong?? P.S. : I'm running Windows XP SP3 and using VS2010 Command Prompt as compiler. P.P.S. : Took me 15 minutes to learn how to format properly.

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  • Using the mpz_powm functions from the GMP/MPIR libraries with negative exponents

    - by Mihai Todor
    Please consider the following code: mpz_t x, n, out; mpz_init_set_ui(x, 2UL); mpz_init_set_ui(n, 7UL); mpz_init(out); mpz_invert(out, x, n); gmp_printf ("%Zd\n", out);//prints 4. 2 * 4 (mod 7) = 1. OK mpz_powm_ui(out, x, -1UL, n);//prints 1. 2 * 1 (mod 7) = 2. How come? gmp_printf ("%Zd\n", out); mpz_clear(x); mpz_clear(n); mpz_clear(out); I am unable to understand how the mpz_powm functions handle negative exponents, although, according to the documentation, it is supposed to support them. I would expect that raising a number to -1 modulo n is equivalent to inverting it modulo n. What am I missing here?

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  • Actionscript NetStream.play drops port in relative URLs

    - by Steve Middleton
    Hi, the current page my flash application is running from is http://localhost:3000/. I'm trying to play a video using NetStream.play(relativeURL) by using a relative URL (e.g. "myVideo.flv"), but when I look at the actual request made by actionscript, it's dropping the port number. (e.g. http://localhost/myVideo.flv). Is there something I can do on the flash side to make this work? Is anyone else having this problem?

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  • Simple, Custom Parsing with c++

    - by bradkovach
    Hi! I have been reading SO for some time now, but I truly cannot find any help for my problem. I have a c++ assignment to create an IAS simulator. Here is some sample code... 0 1 a 1 2 b 2 c 3 1 10 begin 11 . load a, subtract b and offset by -1 for jump+ 11 load M(0) 12 sub M(1) 13 sub M(3) 14 halt Using c++, I need to be able to read these lines and store them in a "memory register" class that I already have constructed... For example, the first line would need to store "1 a" in register zero. How can I parse out the number at the line beginning and then store the rest as a string? I have setup storage using a class that is called using mem.set(int, string);. int is the memory location at the beginning of the line and string is the stored instruction.

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  • How to specify VNC port number with Mac OS X built-in VNC client?

    - by Eonil
    Is it possible to specify VNC port number in built-in VNC client of Mac OS X? I'm trying to connect to Xen VPS machine with Finder's built-in VNC client. I used address like this. vnc://server:port But it fails because it uses another port, and Finder's built-in VNC cannot handle port number. As I know it handles the number after colon as display-number, not a port number. Is there a way to specify port number on the VNC client? Or any workaround for this? (port forwarding??? I have no idea about it...)

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  • How to specify VNC port number with Mac OS X built-in VNC client?

    - by Eonil
    Is it possible to specify VNC port number in built-in VNC client of Mac OS X? I'm trying to connect to Xen VPS machine with Finder's built-in VNC client. I used address like this. vnc://server:port But it fails because it uses another port, and Finder's built-in VNC cannot handle port number. As I know it handles the number after colon as display-number, not a port number. Is there a way to specify port number on the VNC client? Or any workaround for this? (port forwarding??? I have no idea about it...)

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  • Why are bugs responsible for big deficiencies in functionality given such low priority?

    - by keepitsimpleengineer
    Well, first of all, change is inevitable and mostly good. Furthermore attempts at simplifying the User Interface such as Gnome 3, Unity to make Linux more inclusive hold much promise, even though they adversely affect my style of working. Additionally, though now retired, I have worked with computers for 47 years, and though I do nothing serious for others now, I still do heavy duty things. 10.04 LTS is my big workstation, and I had three 10.10 systems for Mythtv, and one of which is further adapted for video & related. The Mythtv were 10.10 because of a dormant bug regarding installing to 10.04. My work habits consistently use dual monitors and compiz cube and 3D windows with the computing horsepower to support them. The dual monitors with separate X screens has been not been functional since 11.04, and cube/3D windows not functional in Unity, and with diminished functionality Gnome. There is a bug filed (after upgrade to 12.04 amd64 Gnome Classic not properly draw second screen) I have mitigated the situation some by switching to Xubuntu and eschewing Unity. The question that comes to mind is why this bug is not given more attention in that it nearly cuts functionality in half for more competent workstations. Sample workspace... Please know that I appreciate all the hard work, dedication require to pull off something as big as Ubuntu et al.

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  • Is a big name computer science degree worth the cost?

    - by Serplat
    I'm currently in High School and trying to look into what I want to do after I graduate. I know that I will be going to college, and that I want a degree in Computer Science, however, I'm not entirely sure where I want to go (I haven't started the application process yet). I already have built up a decent amount of experience in programming (over the summers I have been hired to program at a local university), and I'm pretty capable of teaching myself most of the material I've come across through either books or web documentation. I'm interested in whether it is worth it to get a degree from a major, big-name computer science university for $50,000 each year, as opposed to going to a local state school for only $20,000. For my Bachelor's degree alone, this would be $120,000 more than the state school. I've also heard that where you get your Bachelor's doesn't matter much if you plan to get a Master's degree. Many people recommend going somewhere like a state school for your Bachelor's, and then try to get into a more major school for your Master's. Has anybody found any truth in this? Basically, is going to a big name computer science school for a Bachelor's degree really worth the added expense?

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  • "Malformed version number string mingw32" when starting rails

    - by Freewind
    My os: windows xp, ruby: 1.8.7, rails: 2.3.5 Everything was fine, but I just installed a "gcc-4.4.0-mingw32-bin", and run gem install rdiscount, then my rails can't start. Now when I run ruby script/server, or rake gems:install, the following error will occur: rake aborted! Malformed version number string mingw32 (See full trace by running task with --trace) E:\WORKSPACE_TOPCODER\wenda_ror>ruby script/server => Booting Mongrel => Rails 2.3.5 application starting on http://0.0.0.0:3000 E:/Ruby/ruby-187/lib/ruby/site_ruby/1.8/rubygems/version.rb:182:in `initialize': Malformed version number string mingw32 (ArgumentError) from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:105:in `new' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:105:in `version_for_dir' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:47:in `refresh!' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:45:in `each' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:45:in `refresh!' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/vendor_gem_source_index.rb:29:in `initialize' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/gem_dependency.rb:21:in `new' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/gem_dependency.rb:21:in `add_frozen_gem_path' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:298:in `add_gem_load_paths' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:132:in `process' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run' from E:/WORKSPACE_TOPCODER/wenda_ror/config/environment.rb:9 from E:/Ruby/ruby-187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from E:/Ruby/ruby-187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' from E:/Ruby/ruby-187/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' Now I have re-installed my ruby and rails, but the same error still occurs. And I have searched in google, found no solution. It seems I have to re-install my windows xp. Somebody knows the reason? Help...

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