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  • FluentNHibernate error -- "Invalid object name"

    - by goober
    I'm attempting to do the most simple of mappings with FluentNHibernate & Sql2005. Basically, I have a database table called "sv_Categories". I'd like to add a category, setting the ID automatically, and adding the userid and title supplied. Database table layout: CategoryID -- int -- not-null, primary key, auto-incrementing UserID -- uniqueidentifier -- not null Title -- varchar(50) -- not null Simple. My SessionFactory code (which works, as far as I can tell): _SessionFactory = Fluently.Configure().Database( MsSqlConfiguration.MsSql2005 .ConnectionString(c => c.FromConnectionStringWithKey("SVTest"))) .Mappings(x => x.FluentMappings.AddFromAssemblyOf<CategoryMap>()) .BuildSessionFactory(); My ClassMap code: public class CategoryMap : ClassMap<Category> { public CategoryMap() { Id(x => x.ID).Column("CategoryID").Unique(); Map(x => x.Title).Column("Title").Not.Nullable(); Map(x => x.UserID).Column("UserID").Not.Nullable(); } } My Class code: public class Category { public virtual int ID { get; private set; } public virtual string Title { get; set; } public virtual Guid UserID { get; set; } public Category() { // do nothing } } And the page where I save the object: public void Add(Category catToAdd) { using (ISession session = SessionProvider.GetSession()) { using (ITransaction Transaction = session.BeginTransaction()) { session.Save(catToAdd); Transaction.Commit(); } } } I receive the error Invalid object name 'Category'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Invalid object name 'Category'. I think it might be that I haven't told the CategoryMap class to use the "sv_Categories" table, but I'm not sure how to do that. Any help would be appreciated. Thanks!

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  • File upload issue

    - by Varun
    I am working on a PHP based, ticket management system. While creating a ticket, one can upload an attachment. I want to put a limit (say 10 MB) per file upload. To implement this I plan the following- 1. In php.ini set post_max_size = 10M 2.In PHP script which receives the POST- Since the file is larger than post_max_size, $_FILES[] will be empty. But I can still check the content-length header and discard the upload, if size more than 10M. While testing this I tried uploading a file of 1 GB and analysed the http traffic and this is what I found. - the entire 1 GB data is first uploaded to a to the server temporarily and discarded once the http request completes. Though I couldn't exactly find out where the file was getting saved(as it was not there in the temporary directory in the server.), but my http traffic analyzer showed that the browser did send 1 GB data to the server. - the PHP script execution started only after completion of the http request(i.e after uploading the entire 1 GB) Now I have 2 concerns: a) People may exploit my server bandwidth by trying to upload large file, which I will have to discard anyways. b) Even worse, if someone starts uploading a huge file (say 100 GB), entire 100 GB data is first uploaded to the server temporarily, that means for that period, it will consume that much of memory on my server. What's the common solution for this. Am I missing something here?

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  • I need a fast runtime expression parser

    - by Chris Lively
    I need to locate a fast, lightweight expression parser. Ideally I want to pass it a list of name/value pairs (e.g. variables) and a string containing the expression to evaluate. All I need back from it is a true/false value. The types of expressions should be along the lines of: varA == "xyz" and varB==123 Basically, just a simple logic engine whose expression is provided at runtime. UPDATE At minimum it needs to support ==, !=, , =, <, <= Regarding speed, I expect roughly 5 expressions to be executed per request. We'll see somewhere in the vicinity of 100/requests a second. Our current pages tend to execute in under 50ms. Usually there will only be 2 or 3 variables involved in any expression. However, I'll need to load approximately 30 into the parser prior to execution. UPDATE 2012/11/5 Update about performance. We implemented nCalc nearly 2 years ago. Since then we've expanded it's use such that we average 40+ expressions covering 300+ variables on post backs. There are now thousands of post backs occurring per second with absolutely zero performance degradation. We've also extended it to include a handful of additional functions, again with no performance loss. In short, nCalc met all of our needs and exceeded our expectations.

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  • can JockerSoft.Media read/get video file from remote location?

    - by Lynx
    here is the code for JockerSoft.Media // Path of the video and frame storing path string _videopath = "http://www.test.com/Video/test.avi"; //"C:\\test.avi"; string _imagepath = "C:\\test.jpg" Bitmap bmp = FrameGrabber.GetFrameFromVideo(_videopath, 0.1d); bmp.Save(_imagepath, System.Drawing.Imaging.ImageFormat.Gif); // Save directly frame on specified location FrameGrabber.SaveFrameFromVideo(_videopath, 0.1d, _imagepath); it work perfectly is the video file is from my own computer, but when i try to get video file from remote location it not getting the frame. well, all the example is for windwos form app and i trying to use this for web-application. is there maybe an additional coding that enable me to use jockersoft to grab a video frame from remote location? here is the error that i got: Attempted to access an unloaded appdomain. (Exception from HRESULT: 0x80131014) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.AppDomainUnloadedException: Attempted to access an unloaded appdomain. (Exception from HRESULT: 0x80131014) New Learner, please guide me..

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  • Preprocessor #define vs. function pointer - best practice?

    - by Dustin
    I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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  • Templates, Function Pointers and C++0x

    - by user328543
    One of my personal experiments to understand some of the C++0x features: I'm trying to pass a function pointer to a template function to execute. Eventually the execution is supposed to happen in a different thread. But with all the different types of functions, I can't get the templates to work. #include `<functional`> int foo(void) {return 2;} class bar { public: int operator() (void) {return 4;}; int something(int a) {return a;}; }; template <class C> int func(C&& c) { //typedef typename std::result_of< C() >::type result_type; typedef typename std::conditional< std::is_pointer< C >::value, std::result_of< C() >::type, std::conditional< std::is_object< C >::value, std::result_of< typename C::operator() >::type, void> >::type result_type; result_type result = c(); return result; } int main(int argc, char* argv[]) { // call with a function pointer func(foo); // call with a member function bar b; func(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); // call with a lambda expression func( [](void)->int {return 12;} ); return 0; } The result_of template alone doesn't seem to be able to find the operator() in class bar and the clunky conditional I created doesn't compile. Any ideas? Will I have additional problems with const functions?

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  • Trouble tunneling my local Wordpress install to the mysql database on appfog

    - by alanmoo
    I've set up a wordpress install on appfog (using rackspace), and cloned the install to my local machine for development. I know the install works (using MAMP) because I created a local mysql database and changed wp-config.php to point to it. However, I want to develop without having to change wp-config.php every time I commit. After doing some research, it seems like the Appfog service Caldecott lets me tunnel into the mysql database on the server, using af tunnel. Unfortunately, I'm having issues with getting it working. Even if I change my MAMP mysql port to something like 8889, and tunnel mysql through port 3306, it looks like it's connected but I still get "Error establishing a database connection" when loading my localhost Wordpress. When I quit the mysql monitor (using ctrl+x, ctrl+c), I get a message stating "Error: 'mysql' execution failed; is it in your $PATH?'. Originally, no, it wasn't, but I've fixed my PATH variable on my local machine so that when I go to Terminal and just type mysql, it loads up. So I guess my question is 2 parts: 1.)Am I going with the right approach for Wordpress development on my local machine and 2.)If so, why is the tunnel not working?

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  • Scheme Function to reverse elements of list of 2-list

    - by sudhirc
    This is an exercise from EOPL. Procedure (invert lst) takes lst which is a list of 2-lists and returns a list with each 2-list reversed. (define invert (lambda (lst) (cond((null? lst ) '()) ((= 2 (rtn-len (car lst))) ( cons(swap-elem (car lst)) (invert (cdr lst)))) ("List is not a 2-List")))) ;; Auxiliry Procedure swap-elements of 2 element list (define swap-elem (lambda (lst) (cons (car (cdr lst)) (car lst)))) ;; returns lengh of the list by calling (define rtn-len (lambda (lst) (calc-len lst 0))) ;; calculate length of the list (define calc-len (lambda (lst n) (if (null? lst) n (calc-len (cdr lst) (+ n 1))))) This seems to work however looks very verbose. Can this be shortened or written in more elegant way ? How I can halt the processing in any of the individual element is not a 2-list? At the moment execution proceed to next member and replacing current member with "List is not a 2-List" if current member is not a 2-list.

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  • What is a modern C++ approach to structures containing symbolic constants?

    - by Ken
    enum bool { FALSE = 0, TRUE = 1 }; I'm wondering how to translate this in a modern C++ approach and if there is a well suited container for that; i know that the enum are not really that appreciated, but i can't think about a real alternative in the C++ world. What if would like to associate the execution of a particular method with a state? Ok, this is the part where i will be more verbose. I would like to stress the fact that i'm asking about structures symbolic constants and not about TRUE and FALSE, i'm not that "needy". Suppose that i have a structure that can represent several states with their own constants enum semaphore { GREEN = 0, ORANGE = 1, RED = 2 }; this is C code, now my question is about how to do the same in C++ if there is a better way. My question continue when i ask about the possibility to do something like an automatic triggering when a change of state will occur, for example: int main{ ... semaphore = 1; ... } and without any extra statements this has to trigger a method() just because the semaphore is now orange. I hope that is more clear now.

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  • Slow query. Wrong database structure?

    - by Tin
    I have a database with table that contains tasks. Tasks have a lifecycle. The status of the task's lifecycle can change. These state transitions are stored in a separate table tasktransitions. Now I wrote a query to find all open/reopened tasks and recently changed tasks but I already see with a rather small number of tasks (<1000) that execution time has becoming very long (0.5s). Tasks +-------------+---------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------+------+-----+---------+----------------+ | taskid | int(11) | NO | PRI | NULL | auto_increment | | description | text | NO | | NULL | | +-------------+---------+------+-----+---------+----------------+ Tasktransitions +------------------+-----------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------+-----------+------+-----+-------------------+----------------+ | tasktransitionid | int(11) | NO | PRI | NULL | auto_increment | | taskid | int(11) | NO | MUL | NULL | | | status | int(11) | NO | MUL | NULL | | | description | text | NO | | NULL | | | userid | int(11) | NO | | NULL | | | transitiondate | timestamp | NO | | CURRENT_TIMESTAMP | | +------------------+-----------+------+-----+-------------------+----------------+ Query SELECT tasks.taskid,tasks.description,tasklaststatus.status FROM tasks LEFT OUTER JOIN ( SELECT tasktransitions.taskid,tasktransitions.transitiondate,tasktransitions.status FROM tasktransitions INNER JOIN ( SELECT taskid,MAX(transitiondate) AS lasttransitiondate FROM tasktransitions GROUP BY taskid ) AS tasklasttransition ON tasklasttransition.lasttransitiondate=tasktransitions.transitiondate AND tasklasttransition.taskid=tasktransitions.taskid ) AS tasklaststatus ON tasklaststatus.taskid=tasks.taskid WHERE tasklaststatus.status IS NULL OR tasklaststatus.status=0 or tasklaststatus.transitiondate>'2013-09-01'; I'm wondering if the database structure is best choice performance wise. Could adding indexes help? I already tried to add some but I don't see great improvements. +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | tasktransitions | 0 | PRIMARY | 1 | tasktransitionid | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | taskid_date_ix | 1 | taskid | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | taskid_date_ix | 2 | transitiondate | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | status_ix | 1 | status | A | 3 | NULL | NULL | | BTREE | | | +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ Any other suggestions?

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  • Connection string problems on shared hosting with sql server 2005 express

    - by dagogo
    hi i have problem connecting to my db on a shared hosting, my host provider says they deployed sql 2005 express on their database and i prepared my connection string as follows to take advantage of sql express. \ the data source nae i used originally was ./SQLExpress but my host provider asked that i change it to local host, although with the former it didnt connect, but still with the change as indicated above the error still comes up on access to my default page. the error is as follows; Server Error in '/' Application. Invalid value for key 'attachdbfilename'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.ArgumentException: Invalid value for key 'attachdbfilename'. Source Error: Line 120: Public Function GetID(ByVal sLgaName As String) As Integer Line 121: Dim q As String = "Select PLID " & "From LGA " & "Where LGAName = " & "'" & sLgaName & "'" Line 122: Dim cn As New SqlConnection(Me.ConnectionString) Line 123: Dim cmd As New SqlCommand(q, cn) Line 124: ive read up a lot on the web and googled ma fingers numb on this, i have a deadline to deliver this project and having successfully built the app it frustrating for this to happen. pls help me.

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  • How to speed-up a simple method (preferably without changing interfaces or data structures)?

    - by baol
    I have some data structures: all_unordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::tr1::unordered_map<size_t, size_t> position_m; const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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  • Extra NotifyIcon shown in system tray

    - by Kettch19
    I'm having an issue with an app where my NotifyIcon displays an extra icon. The steps to reproduce it are easy, but the problem is that the extra icon shows up after any of the actual codebehind we've added fires. Put simply, clicking a button triggers execution of method FooBar() which runs all the way through fine but its primary duty is to fire a backgroundworker to log into another of our apps. It only appears if this particular button is clicked. Strangely enough, we have a WndProc method override and if I step through until the extra NotifyIcon appears, it always appears during this method so something else beyond the codebehind must be triggering the behavior. Our WndProc method is currently (although I don't think it's caused by the WndProc): Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message) 'Check for WM_COPYDATA message from other app or drag/drop action and handle message If m.Msg = NativeMethods.WM_COPYDATA Then ' get the standard message structure from lparam Dim CD As NativeMethods.COPYDATASTRUCT = m.GetLParam(GetType(NativeMethods.COPYDATASTRUCT)) 'setup byte array Dim B(CD.cbData) As Byte 'copy data from memory into array Runtime.InteropServices.Marshal.Copy(New IntPtr(CD.lpData), B, 0, CD.cbData) 'Get message as string and process ProcessWMCopyData(System.Text.Encoding.Default.GetString(B)) 'empty array Erase B 'set message result to 'true', meaning message handled m.Result = New IntPtr(1) End If 'pass on result and all messages not handled by this app MyBase.WndProc(m) End Sub The only place in the code where the NotifyIcon in question is manipulated at all is in the following event handler (again, don't think this is the culprit, but just for more info): Private Sub TrayIcon_MouseDoubleClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TrayIcon.MouseDoubleClick If Me.Visible Then Me.Hide() Else PositionBottomRight() Me.Show() End If End Sub The backgroundworker's DoWork is as follows (just a class call to log in to our other app, but again just for info): Private Sub LoginBackgroundWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles LoginBackgroundWorker.DoWork Settings.IsLoggedIn = _wdService.LogOn(Settings.UserName, Settings.Password) End Sub Does anyone else have ideas on what might be causing this or how to possibly further debug this? I've been banging my head on this without seeing a pattern so another set of eyes would be extremely appreciated. :) I've posted this on MSDN winforms forums as well and have had no luck there so far either.

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  • Getting values from another winform and passing it to current!

    - by klm9971
    Hello: I have 2 windows forms. The 1st one who gets active during start of the program has a button in which another 2nd windows form appears which has text field in which user type their name and HIT okay. Now in the 1st form I have a variable name: nameproccessed which takes the name from the second form. But the problem is my button which is in the 1st form has more functions besides taking name, how can I stop the flow of the compiler to take first the name from the second form and then process the rest execution of the function??? Here is the snippet of my code: //1st form //Class1 public string _nameProcessed = ""; private void btnGetSomething_Click(object sender, EventArgs e) { showdial(); //some more functionalities in this function!!! } private void showdial() { InputName inm = new InputName(); inm.Show(); } //2nd form //Class2 public string name; private void btnEnterName_Click(object sender, EventArgs e) { name = tbxName.Text; Class1 ict = new Class1(); ict._nameProcessed = name; this.Close(); } Now I want to take the 'name' from the second form put it on the _nameprocessed in the 1st form and then execute the rest of the function. How can I do that? Any help!

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  • jQuery and executing code until mouseout is called

    - by Tomaszewski
    Good day all, I am tasked with building a slider for our site. Here is my goal: <div id="abc"> <div id="slider">...</div> </div> I need to move "slider" left 30px at a time when a button is hovered over, and right 30px when another button is hovered over. My problem is that there doesn't seem to be a reliable method for telling the code that the mouse hasn't left the are in question, unless there is something I did not think about or read yet. In other words, when the mouse is OVER the a button, the code to move "slider" left is executed until the mouseout is called. I'm not really sure how to do this. The only way I can think of is to look at the offsetTop and offsetLeft and offsetTop DOM properties and compare them to the mouse position, than run checks to see if the mouse is within the bounds of the box, and if not than it will stop the execution of code. Is there a better way to do this?

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  • What do you call a set of Javascript closures that share a common context?

    - by Ed Stauff
    I've been trying to learn closures (in Javascript), which kind of hurts my brain after way too many years with C# and C++. I think I now have a basic understanding, but one thing bothers me: I've visited lots of websites in this Quest for Knowledge, and nowhere have I seen a word (or even a simple two-word phrase) that means "a set of Javascript closures that share a common execution context". For example: function CreateThingy (name, initialValue) { var myName = name; var myValue = initialValue; var retObj = new Object; retObj.getName = function() { return myName; } retObj.getValue = function() { return myValue; } retObj.setValue = function(newValue) { myValue = newValue; } return retObj; }; From what I've read, this seems to be one common way of implementing data hiding. The value returned by CreateThingy is, of course, an object, but what would you call the set of functions which are properties of that object? Each one is a closure, but I'd like a name I can used to describe (and think about) all of them together as one conceptual entity, and I'd rather use a commonly accepted name than make one up. Thanks! -- Ed

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  • How to speed-up a simple method? (possibily without changing interfaces or data structures)

    - by baol
    Hello. I have some data structures: all_unordered_mordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::map<size_t, size_t> position_m; // positions of strings in ordered_m const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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  • segmentation fault while using format string to scan input

    - by Aman Deep Gautam
    consider the code and its result: while ((row = mysql_fetch_row (table_info)) != NULL) { answer='\0'; printf ( "%s: ", row[0] ); scanf ( "%c", &answer ); getchar(); if ( answer == 'y') { printf ( "*****\n" ); table_name[index] = malloc ( strlen(row[0]) + 1 ); printf ( "*****\n" ); memcpy ( &table_name[index], &row[0], strlen(row[0]) + 1 ); } printf ( "finally inserted: %s \n", table_name[index]); } The result on execution: 1_time_access: y ***** ***** finally inserted: 1_time_access 2_time_access: y ***** ***** finally inserted: 2_time_access 39_time_access: y ***** ***** finally inserted: 39_time_access Explanation of result: row[0] has value 1_time_access, 2_time_access, 39_time_access. Now Consider a better way of doing it which is using a format string to escape the \n. I run the following code but it gives segentation fault, I cannot understand why. Code: while ((row = mysql_fetch_row (table_info)) != NULL) { answer='\0'; printf ( "%s: ", row[0] ); scanf ( "%[^\n]%*c", &answer ); if ( answer == 'y') { printf ( "*****\n" ); fflush(stdout); table_name[index] = malloc ( strlen(row[0]) + 1 ); printf ( "*****\n" ); fflush(stdout); memcpy ( &table_name[index], &row[0], strlen(row[0]) + 1 ); } printf ( "finally inserted: %s \n", table_name[index]); fflush(stdout); } Result: 1_time_access: y ***** ./set-env.sh: line 17: 15263 Segmentation fault (core dumped) ./exec dataset_one (do not worry about set-env.sh, it is the script running th program.) I canot understand why this is happening.

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  • What wrapper class in C++ should I use for automated resource management?

    - by Vilx-
    I'm a C++ amateur. I'm writing some Win32 API code and there are handles and weirdly compositely allocated objects aplenty. So I was wondering - is there some wrapper class that would make resource management easier? For example, when I want to load some data I open a file with CreateFile() and get a HANDLE. When I'm done with it, I should call CloseHandle() on it. But for any reasonably complex loading function there will be dozens of possible exit points, not to mention exceptions. So it would be great if I could wrap the handle in some kind of wrapper class which would automatically call CloseHandle() once execution left the scope. Even better - it could do some reference counting so I can pass it around in and out of other functions, and it would release the resource only when the last reference left scope. The concept is simple - but is there something like that in the standard library? I'm using Visual Studio 2008, by the way, and I don't want to attach a 3rd party framework like Boost or something.

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  • Why does reusing arrays increase performance so significantly in c#?

    - by Willem
    In my code, I perform a large number of tasks, each requiring a large array of memory to temporarily store data. I have about 500 tasks. At the beginning of each task, I allocate memory for an array : double[] tempDoubleArray = new double[M]; M is a large number depending on the precise task, typically around 2000000. Now, I do some complex calculations to fill the array, and in the end I use the array to determine the result of this task. After that, the tempDoubleArray goes out of scope. Profiling reveals that the calls to construct the arrays are time consuming. So, I decide to try and reuse the array, by making it static and reusing it. It requires some additional juggling to figure out the minimum size of the array, requiring an extra pass through all tasks, but it works. Now, the program is much faster (from 80 sec to 22 sec for execution of all tasks). double[] tempDoubleArray = staticDoubleArray; However, I'm a bit in the dark of why precisely this works so well. Id say that in the original code, when the tempDoubleArray goes out of scope, it can be collected, so allocating a new array should not be that hard right? I ask this because understanding why it works might help me figuring out other ways to achieve the same effect, and because I would like to know in what cases allocation gives performance issues.

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  • Trouble with go tour crawler exercise

    - by David Mason
    I'm going through the go tour and I feel like I have a pretty good understanding of the language except for concurrency. On slide 71 there is an exercise that asks the reader to parallelize a web crawler (and to make it not cover repeats but I haven't gotten there yet.) Here is what I have so far: func Crawl(url string, depth int, fetcher Fetcher, ch chan string) { if depth <= 0 { return } body, urls, err := fetcher.Fetch(url) if err != nil { ch <- fmt.Sprintln(err) return } ch <- fmt.Sprintf("found: %s %q\n", url, body) for _, u := range urls { go Crawl(u, depth-1, fetcher, ch) } } func main() { ch := make(chan string, 100) go Crawl("http://golang.org/", 4, fetcher, ch) for i := range ch { fmt.Println(i) } } The issue I have is where to put the close(ch) call. If I put a defer close(ch) somewhere in the Crawl method, then I end up writing to a closed channel in one of the spawned goroutines, since the method will finish execution before the spawned goroutines do. If I omit the call to close(ch), as is shown in my example code, the program deadlocks after all the goroutines finish executing but the main thread is still waiting on the channel in the for loop since the channel was never closed.

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  • How to execute python script on the BaseHTTPSERVER created by python?

    - by user1731699
    I have simply created a python server with : python -m SimpleHTTPServer I had a .htaccess (I don't know if it is usefull with python server) with: AddHandler cgi-script .py Options +ExecCGI Now I am writing a simple python script : #!/usr/bin/python import cgitb cgitb.enable() print 'Content-type: text/html' print ''' <html> <head> <title>My website</title> </head> <body> <p>Here I am</p> </body> </html> ''' I make test.py (name of my script) an executed file with: chmod +x test.py I am launching in firefox with this addres: (http : //) 0.0.0.0:8000/test.py Problem, the script is not executed... I see the code in the web page... And server error is: localhost - - [25/Oct/2012 10:47:12] "GET / HTTP/1.1" 200 - localhost - - [25/Oct/2012 10:47:13] code 404, message File not found localhost - - [25/Oct/2012 10:47:13] "GET /favicon.ico HTTP/1.1" 404 - How can I manage the execution of python code simply? Is it possible to write in a python server to execute the python script like with something like that: import BaseHTTPServer import CGIHTTPServer httpd = BaseHTTPServer.HTTPServer(\ ('localhost', 8123), \ CGIHTTPServer.CGIHTTPRequestHandler) ###  here some code to say, hey please execute python script on the webserver... ;-) httpd.serve_forever() Or something else...

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  • If I cast an IQueryable as an IEnumerable then call a Linq extension method, which implementation gets called?

    - by James Morcom
    Considering the following code: IQueryable<T> queryable; // something to instantiate queryable var enumerable = (IEnumerable<T>) queryable; var filtered = enumerable.Where(i => i > 3); In the final line, which extension method gets called? Is it IEnumerable<T>.Where(...)? Or will IQueryable<T>.Where(...) be called because the actual implementation is still obviously a queryable? Presumably the ideal would be for the IQueryable version to be called, in the same way that normal polymorphism will always use the more specific override. In Visual Studio though when I right-click on the Where method and "Go to Definition" I'm taken to the IEnumerable version, which kind of makes sense from a visual point-of-view. My main concern is that if somewhere in my app I use Linq to NHibernate to get a Queryable, but I pass it around using an interface that uses the more general IEnumerable signature, I'll lose the wonders of deferred database execution!

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  • Add Source file link to the default ASP.NET Server Error page?

    - by Max Schilling
    Has anyone ever thought to attempt to modify the default ASP.NET Server error page to provide a link BACK to the error source in Visual Studio? Consider the following standard error page in ASP.NET: Server Error in '/myproject' Application. Invalid object name 'usp_DoSomething'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Invalid object name 'usp_DoSomething'. Source Error: Line 4323: cmd.CommandText = "usp_DoSomething"; Line 4324: Line 4325: using (var dr = cmd.ExecuteReader()) Line 4326: { Line 4327: if (dr != null) Source File: c:\development\myproject\myproject.components\providers\sql\sqldataprovider.cs Line: 4325 When an error like this is generated, the HTML has the source back to the file the error occurs in and the line number. Has anyone ever written or thought of writing some mechanism to turn the text into a link back to the error in Visual Studio? I've never seen anything that does it, but it just seems like it would be a helluva nice feature and I think about it in the back of my mind every time an error occurs when I have to manually go find it in the source. It would just be nice to be able to click a link to take me straight there. Anyone written any, or know of any solutions for this. I use Chrome or Firefox as my browsers of choice, but I'd even consider using IE again if someone found a plugin that did this. Thanks, Max

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  • Error with threads during automatic testing on TeamCity 5

    - by yeyeyerman
    Hello, I'm having some problems executing the tests of the application I'm developing. All the tests execute normally with ReSharper and in NCover. However, the execution of one of these tests in TeamCity is generating an error. This test initializes two objects, the object under test and a simulator of a real object. Both objects will communicate throug a serial link in a representation of the real scenario. ObjectSimulator r_simulator = new ObjectSimulator(...); ObjectDriver r_driver = new ObjectDriver(...); Assert.IsTrue(r_driver.Connect() == ErrorCode.Success); The simulator just do the following in the constructor public class ObjectSimulator { ... public ObjectSimulator() { // serial port configuration m_port = new SerialPort(); m_port.DataReceived += DataReceivedEvent; } ... } The main object has two threads. The main thread of the application and a timer to refresh a watchdog timer in the real object. public ErrorCode Connect() { ... StartSynchroTimer(); Thread.Sleep(4); // to check if the timer is working properly ... } The problem is comming from the Thread.Sleep() call, as when I remove it everything works. It seems like the ObjectSimulator also sleeps and doesn't receive the DataReceived event. How can I resolve this issue?

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