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  • Strange compiler complaint when using similar code

    - by Jason
    For a project, I have to ask the user for a file name, and I'm reading it in character by character using getchar. From the main, I call the function char *coursename= introPrint(); //start off to print the usage directions and get the first bit of input. That function is defined as char *introPrint(){ int size= 20; int c; int length=0; char buffer[size]; //instructions printout, cut for brevity //get coursename from user and return it while ( (c=getchar()) != EOF && (c != '\n') ){ buffer[length++]= c; if (length==size-1) break; } buffer[length]=0; return buffer; } This is basically identical code I wrote to ask the user for input, replace the character echo with asterisks, then print out the results. Here, though, I'm getting a function returns address of local variable warning for the return statement. So why am I getting no warnings from the other program, but trigger one for this code?

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  • Is it possible to create multi-tiered WHERE statements in mySQL

    - by Brendan
    I'm currently developing a program that will generate reports based upon lead data. My issue is that I'm running 3 queries for something that I would like to only have to run one query for. For instance, I want to gather data for leads generated in the past day submission_date > (NOW() - INTERVAL 1 DAY) and I would like to find out how many total leads there were, and how many sold leads there were in that timeframe. (sold=1 / sold=0). The issue comes with the fact that this query is currently being done with 2 queries, one with WHEREsold= 1 and one with WHEREsold= 0. This is all well and good, but when I want to generate this data for the past day,week,month,year,and all time I will have to run 10 queries to obtain this data. I feel like there HAS to be a more efficient way of doing this. I know I can create a mySQL function for this, but I don't see how this could solve the problem. Thanks!!

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  • Multiple column sorting (SQL SERVER 2005)

    - by Newbie
    I have a table which looks like Col1 col2 col3 col4 col5 1 5 1 4 6 1 4 0 3 7 0 1 5 6 3 1 8 2 1 5 4 3 2 1 4 The script is declare @t table(col1 int, col2 int, col3 int,col4 int,col5 int) insert into @t select 1,5,1,4,6 union all select 1,4,0,3,7 union all select 0,1,5,6,3 union all select 1,8,2,1,5 union all select 4,3,2,1,4 I want the output to be every column being sorted in ascending order i.e. Col1 col2 col3 col4 col5 0 1 0 1 3 1 3 1 1 4 1 4 2 3 5 1 5 2 4 6 4 8 5 6 7 I already solved tye problem by the folowing program Select x1.col1 ,x2.col2 ,x3.col3 ,x4.col4 ,x5.col5 From (Select Row_Number() Over(Order By col1) rn1, col1 From @t)x1 Join(Select Row_Number() Over(Order By col2) rn2, col2 From @t)x2 On x1.rn1=x2.rn2 Join(Select Row_Number() Over(Order By col3) rn3, col3 From @t)x3 On x1.rn1=x3.rn3 Join(Select Row_Number() Over(Order By col4) rn4, col4 From @t)x4 On x1.rn1=x4.rn4 Join(Select Row_Number() Over(Order By col5) rn5, col5 From @t)x5 On x1.rn1=x5.rn5 But I am not happy with this solution. Is there any better way to achieve the same? (Using set based approach) If so, could any one please show an example. Thanks

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  • How do I use XPath with a default namespace with no prefix?

    - by Scott Stafford
    What is the XPath (in C# API to XDocument.XPathSelectElements(xpath, nsman) if it matters) to query all MyNodes from this document? <?xml version="1.0" encoding="utf-8"?> <configuration> <MyNode xmlns="lcmp" attr="true"> <subnode /> </MyNode> </configuration I tried /configuration/MyNode which is wrong because it ignores the namespace. I tried /configuration/lcmp:MyNode which is wrong because lcmp is the URI, not the prefix. I tried /configuration/{lcmp}MyNode which failed because Additional information: '/configuration/{lcmp}MyNode' has an invalid token. EDIT: I can't use mgr.AddNamespace("df", "lcmp"); as some of the answerers have suggested. That requires that the XML parsing program know all the namespaces I plan to use ahead of time. Since this is meant to be applicable to any source file, I don't know which namespaces to manually add prefixes for. It seems like {my uri} is the XPath syntax, but Microsoft didn't bother implementing that... true?

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  • How to "pin" C++/CLI pointers

    - by Kumar
    I am wrapping up a class which reading a custom binary data file and makes the data available to a .net/c# class However a couple of lines down the code, i start getting the memory access violation error which i believe is due to the GC moving memory around, the class is managed Here's the code if ( ! reader.OpenFile(...) ) return ; foreach(string fieldName in fields) { int colIndex = reader.GetColIndex( fieldName ); int colType = reader.GetColType( colIndex ); // error is raised here on 2nd iteration } for ( int r = 0 ; r < reader.NumFields(); r++ ) { foreach(string fieldName in fields) { int colIndex = reader.GetColIndex( fieldName ); int colType = reader.GetColType( colIndex ); // error is raised here on 2nd iteration switch ( colType ) { case 0 : // INT processField( r, fieldName, reader.GetInt(r,colIndex) ); break ; .... } } } .... i've looked at interior_ptr, pin_ptr but they give an error c3160 cannot be in a managed class Any workaround ? BTW, this is my 1st C++ program in a very long time !

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  • Comparing objects and inheritance

    - by ereOn
    Hi, In my program I have the following class hierarchy: class Base // Base is an abstract class { }; class A : public Base { }; class B : public Base { }; I would like to do the following: foo(const Base& one, const Base& two) { if (one == two) { // Do something } else { // Do something else } } I have issues regarding the operator==() here. Of course comparing an instance A and an instance of B makes no sense but comparing two instances of Base should be possible. (You can't compare a Dog and a Cat however you can compare two Animals) I would like the following results: A == B = false A == A = true or false, depending on the effective value of the two instances B == B = true or false, depending on the effective value of the two instances My question is: is this a good design/idea ? Is this even possible ? What functions should I write/overload ? My apologies if the question is obviously stupid or easy, I have some serious fever right now and my thinking abilities are somewhat limited :/ Thank you.

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  • Why null reference exception in SetMolePublicInstance?

    - by OldGrantonian
    I get a "null reference" exception in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, null); The program builds and compiles correctly. There are no complaints about any of the parameters to the method. Here's the specification of SetMolePublicInstance, from the object browser: SetMolePublicInstance(System.Delegate _stub, System.Type receiverType, object _receiver, string name, params System.Type[] parameterTypes) Here are the parameter values for "Locals": + stub {Method = {System.String <StaticMethodUnitTestWithDeq>b__0()}} System.Func<string> + receiverType {Name = "OrigValue" FullName = "OrigValueP.OrigValue"} System.Type {System.RuntimeType} objReceiver {OrigValueP.OrigValue} object {OrigValueP.OrigValue} name "TestString" string parameterTypes null object[] I know that TestString() takes no parameters and returns string, so as a starter to try to get things working, I specified "null" for the final parameter to SetMolePublicInstance. As already mentioned, this compiles OK. Here's the stack trace: Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.ExtendedReflection.Collections.Indexable.ConvertAllToArray[TInput,TOutput](TInput[] array, Converter`2 converter) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMole(Delegate _stub, Type receiverType, Object _receiver, String name, MoleBindingFlags flags, Type[] parameterTypes) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(Delegate _stub, Type receiverType, Object _receiver, String name, Type[] parameterTypes) at DeqP.Deq.Replace[T](Func`1 stub, Type receiverType, Object objReceiver, String name) in C:\0VisProjects\DecP_04\DecP\DeqC.cs:line 38 at DeqPTest.DecCTest.StaticMethodUnitTestWithDeq() in C:\0VisProjects\DecP_04\DecPTest\DeqCTest.cs:line 28 at Starter.Start.Main(String[] args) in C:\0VisProjects\DecP_04\Starter\Starter.cs:line 14 Press any key to continue . . . To avoid the null parameter, I changed the final "null" to "parameterTypes" as in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, parameterTypes); I then tried each of the following (before the line): int[] parameterTypes = null; // if this is null, I don't think the type will matter int[] parameterTypes = new int[0]; object[] parameterTypes = new object[0]; // this would allow for various parameter types All three attempts produce a red squiggly line under the entire line for SetMolePublicInstance Mouseover showed the following message: The best overloaded method match for 'Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(System.Delegate, System.Type, object, string, params System.Type[])' has some invalid arguments. I'm assuming that the first four arguments are OK, and that the problem is with the params array.

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  • Arrays not counting correctly

    - by Nick Gibson
    I know I was just asking a question earlier facepalm This is in Java coding by the way. Well after everyones VERY VERY helpful advice (thank you guys alot) I managed to get over half of the program running how I wanted. Everything is pointing in the arrays where I want them to go. Now I just need to access the arrays so that It prints the correct information randomly. This is the current code that im using: http://pastebin.org/301483 The specific code giving me problems is this: long aa; int abc; for (int i = 0; i < x; i++) { aa = Math.round(Math.random()*10); String str = Long.toString(aa); abc = Integer.parseInt(str); String[] userAnswer = new String[x]; if(abc > x) { JOptionPane.showMessageDialog(null,"Number is too high. \nNumber Generator will reset."); break; } userAnswer[i] = JOptionPane.showInputDialog(null,"Question "+quesNum+"\n"+questions[abc]+"\n\nA: "+a[abc]+"\nB: "+b[abc]+"\nC: "+c[abc]+"\nD: "+d[abc]); answer = userAnswer[i].compareTo(answers[i]); if(answer == 0) { JOptionPane.showMessageDialog(null,"Correct. \nThe Correct Answer is "+answers[abc]+""+i); } else { JOptionPane.showMessageDialog(null,"Wrong. \n The Correct Answer is "+answers[abc]+""+i); }//else

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  • How to create a progress bar while downloading a file using the windows API?

    - by Jorge Chayan
    i'm working on an application in MS Visual C++ using Windows API that must download a file and place it in a folder. I have already implemented the download using URLDownloadToFile function, but i want to create a PROGRESS_CLASS progress bar with marquee style while the file is being downloaded, but it doesn't seems to get animated in the process. This is the function I use for downloading: BOOL SOXDownload() { HRESULT hRez = URLDownloadToFile(NULL, "url","C:\\sox.zip", 0, NULL); if (hRez == E_OUTOFMEMORY ) { MessageBox(hWnd, "Out of memory Error","", MB_OK); return FALSE; } if (hRez != S_OK) { MessageBox(hWnd, "Error downloading sox.", "Error!", MB_ICONERROR | MB_SYSTEMMODAL); return FALSE; } if (hRez == S_OK) { BSTR file = SysAllocString(L"C:\\sox.zip"); BSTR folder = SysAllocString(L"C:\\"); Unzip2Folder(file, folder); ::MessageBoxA(hWnd, "Sox Binaries downloaded succesfully", "Success", MB_OK); } return TRUE; } Later I call inside WM_CREATE (in my main window's message processor): if (!fileExists("C:\\SOX\\SOX.exe")) { components[7] = CreateWindowEx(0, PROGRESS_CLASS, NULL, WS_VISIBLE | PBS_MARQUEE, GetSystemMetrics(SM_CXSCREEN) / 2 - 80, GetSystemMetrics(SM_CYSCREEN) / 2 + 25, 200, 50, hWnd, NULL, NULL, NULL); SetWindowText(components[7], "Downloading SoX"); SendMessage(components[7], PBM_SETRANGE, 0, (LPARAM) MAKELPARAM(0, 50)); SendMessage(components[7], PBM_SETMARQUEE, TRUE, MAKELPARAM( 0, 50)); SOXDownload(); SendMessage(components[7], WM_CLOSE, NULL, NULL); } And as I want, I get a tiny progress bar... But it's not animated, and when I place the cursor over the bar, the cursor indicates that the program is busy downloading the file. When the download is complete, the window closes as i requested: SendMessage(components[7], WM_CLOSE, NULL, NULL); So the question is how can I make the bar move while downloading the file? Considering that i want it done with marquee style for simplicity. Thanks in advance.

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  • How to call windows form from native cpp

    - by Jenuel
    I have an existing project using c/c++ .NET. Currently I have been given a task to create a windows form from my existing code. So i have add new project windows form application in the existing c/c++ projects.form.h, form.cpp has been automatically created. Now I am having problem to call the window from my c files. Even i could not call the form.h file from my c program. Is there any solution for this problem. Listed here is the coding.... login.c int LoginMain(int id,int task) { LoginClear(); LoginEntry(id,task); dp_in = 1; Rep(); //I WOULD LIKE TO CALL THE FORM AT THIS STAGE Cashier(); dp_in = 0; Login(); return(0); } form.cpp [STAThreadAttribute] int main(array ^args) { // Enabling Windows XP visual effects before any controls are created Application::EnableVisualStyles(); Application::SetCompatibleTextRenderingDefault(false); // Create the main window and run it Application::Run(gcnew Form1()); return 0; }

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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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  • gaema twitter handle error..

    - by zjm1126
    i use gaema for twitter user loggin http://code.google.com/p/gaema/ and my code is : class TwitterAuth(WebappAuth, auth.TwitterMixin): pass class TwitterHandler(BaseHandler): def get(self): twitter_auth = TwitterAuth(self) try: if self.request.GET.get("oauth_token", None): twitter_auth.get_authenticated_user(self._on_auth) self.response.out.write('sss') return twitter_auth.authorize_redirect() except RequestRedirect, e: return self.redirect(e.url, permanent=True) self.render_template('index.html', user=None) def _on_auth(self, user): """This function is called immediatelly after an authentication attempt. Use it to save the login information in a session or secure cookie. :param user: A dictionary with user data if the authentication was successful, or ``None`` if the authentication failed. """ if user: # Authentication was successful. Create a session or secure cookie # to keep the user logged in. #self.response.out.write('logged in as '+user['first_name']+' '+user['last_name']) self.response.out.write(user) return else: # Login failed. Show an error message or do nothing. pass # After cookie is persisted, redirect user to the original URL, using # the home page as fallback. self.redirect(self.request.GET.get('redirect', '/')) and the error is : Traceback (most recent call last): File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 511, in __call__ handler.get(*groups) File "D:\zjm_code\gaema\demos\webapp\main.py", line 76, in get twitter_auth.authorize_redirect() File "D:\zjm_code\gaema\demos\webapp\gaema\auth.py", line 209, in authorize_redirect http.fetch(self._oauth_request_token_url(), self.async_callback( File "D:\zjm_code\gaema\demos\webapp\gaema\auth.py", line 239, in _oauth_request_token_url consumer_token = self._oauth_consumer_token() File "D:\zjm_code\gaema\demos\webapp\gaema\auth.py", line 441, in _oauth_consumer_token self.require_setting("twitter_consumer_key", "Twitter OAuth") TypeError: require_setting() takes at most 2 arguments (3 given) thanks

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  • Type-safe generic data structures in plain-old C?

    - by Bradford Larsen
    I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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  • How to iterate properly across a const set?

    - by Jared
    I'm working on a program that's supposed to represent a graph. My issue is in my printAdjacencyList function. Basically, I have a Graph ADT that has a member variable "nodes", which is a map of the nodes of that graph. Each Node has a set of Edge* to the edges it is connected to. I'm trying to iterate across each node in the graph and each edge of a node. void MyGraph::printAdjacencyList() { std::map<std::string, MyNode*>::iterator mit; std::set<MyEdge*>::iterator sit; for (mit = nodes.begin(); mit != nodes.end(); mit++ ) { std::cout << mit->first << ": {"; const std::set<MyEdge*> edges = mit->second->getEdges(); for (sit = edges.begin(); sit != edges.end(); sit++) { std::pair<MyNode*, MyNode*> edgeNodes = *sit->getEndpoints(); } } std::cout << " }" << std::endl; } getEdges is declared as: const std::set<MyEdge*>& getEdges() { return edges; }; and get Endpoints is declared as: const std::pair<MyNode*, MyNode*>& getEndpoints() { return nodes; }; The compiler error I'm getting is: MyGraph.cpp:63: error: request for member `getEndpoints' in `*(&sit)->std::_Rb_tree_const_iterator<_Tp>::operator-> [with _Tp = MyEdge*]()', which is of non-class type `MyEdge* const' MyGraph.cpp:63: warning: unused variable 'edgeNodes' I have figured out that this probably means I'm misusing const somewhere, but I can't figure out where for the life of me. Any information would be appreciated. Thanks!

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  • How to get last Friday of month(s) using .NET

    - by Newbie
    I have a function that returns me only the fridays from a range of dates public static List<DateTime> GetDates(DateTime startDate, int weeks) { int days = weeks * 7; //Get the whole date range List<DateTime> dtFulldateRange = Enumerable.Range(-days, days).Select(i => startDate.AddDays(i)).ToList(); //Get only the fridays from the date range List<DateTime> dtOnlyFridays = (from dtFridays in dtFulldateRange where dtFridays.DayOfWeek == DayOfWeek.Friday select dtFridays).ToList(); return dtOnlyFridays; } Purpose of the function: "List of dates from the Week number specified till the StartDate i.e. If startdate is 23rd April, 2010 and the week number is 1,then the program should return the dates from 16th April, 2010 till the startddate". I am calling the function as: DateTime StartDate1 = DateTime.ParseExact("20100430", "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture); List<DateTime> dtList = Utility.GetDates(StartDate1, 4).ToList(); Now the requirement has changed a bit. I need to find out only the last Fridays of every month. The input to the function will remain same.

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  • solving problems recursively in C

    - by Harry86
    Our professor gave us the following assignment: A "correct" series is one inwhich the sum of its members equals to the index of its first member. The program is supposed to find the length of the LONGEST "correct" series within a series of n numbers. for example: if the input series would be arr[4]={1, 1, 0, 0} the output (longest "correct" series) would be 3. arr[0]=1. 0!=1 therefore the longest series here is 0. arr[1]=1,and 1=1. but the follwing members also sum up to 1 as shown below: 1=arr[1]+arr[2]+arr[3] = 1+ 0 + 0, therefore the longest series here is 3. the output in this example is 3. That's what I got so far: int solve(int arr[], int index, int length,int sum_so_far) { int maxwith,maxwithout; if(index==length) return 0; maxwith = 1+ solve(arr,index+1,length,sum_so_far+arr[index]); maxwithout = solve(arr,index+1,length,arr[index+1]); if(sum_so_far+arr[index]==index) if(maxwith>maxwithout) return maxwith; return maxwithout; return 0; } int longestIndex(int arr[], int index,int length) { return solve(arr,0,length,0); } What am I doing wrong here? Thanks a lot for your time... Harry

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  • Scope of the c++ using directive

    - by ThomasMcLeod
    From section 7.3.4.2 of the c++11 standard: A using-directive specifies that the names in the nominated namespace can be used in the scope in which the using-directive appears after the using-directive. During unqualified name lookup (3.4.1), the names appear as if they were declared in the nearest enclosing namespace which contains both the using-directive and the nominated namespace. [ Note: In this context, “contains” means “contains directly or indirectly”. —end note ] What do the second and third sentences mean exactly? Please give example. Here is the code I am attempting to understand: namespace A { int i = 7; } namespace B { using namespace A; int i = i + 11; } int main(int argc, char * argv[]) { std::cout << A::i << " " << B::i << std::endl; return 0; } It print "7 7" and not "7 18" as I would expect. Sorry for the typo, the program actually prints "7 11".

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  • How to update a string property of an sqlite database item

    - by Thomas Joos
    hi all, I'm trying to write an application that checks if there is an active internet connection. If so it reads an xml and checks every 'lastupdated' item ( php generated string ). It compares it to the database items and if there is a new value, this particular item needs to be updated. My code seems to work ( compiles, no error messages, no failures, .. ) but I notice that the particular property does not change, it becomese (null). When I output the binded string value it returns the correct string value I want to update into the db.. Any idea what I'm doing wrong? const char *sql = "update myTable Set last_updated=? Where node_id =?"; sqlite3_stmt *statement; // Preparing a statement compiles the SQL query into a byte-code program in the SQLite library. // The third parameter is either the length of the SQL string or -1 to read up to the first null terminator. if (sqlite3_prepare_v2(database, sql, -1, &statement, NULL) == SQLITE_OK){ NSLog(@"last updated item: %@", [d lastupdated]); sqlite3_bind_text(statement, 1, [d lastupdated],-1,SQLITE_TRANSIENT); sqlite3_bind_int (statement, 2, [d node_id]); }else { NSLog(@"SQLite statement error!"); } if(SQLITE_DONE != sqlite3_step(statement)){ NSAssert1(0, @"Error while updating. '%s'", sqlite3_errmsg(database)); }else { NSLog(@"SQLite Update done!"); }

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  • unbuffered I/O in Linux

    - by stuck
    I'm writing lots and lots of data that will not be read again for weeks - as my program runs the amount of free memory on the machine (displayed with 'free' or 'top') drops very quickly, the amount of memory my app uses does not increase - neither does the amount of memory used by other processes. This leads me to believe the memory is being consumed by the filesystems cache - since I do not intend to read this data for a long time I'm hoping to bypass the systems buffers, such that my data is written directly to disk. I dont have dreams of improving perf or being a super ninja, my hope is to give a hint to the filesystem that I'm not going to be coming back for this memory any time soon, so dont spend time optimizing for those cases. On Windows I've faced similar problems and fixed the problem using FILE_FLAG_NO_BUFFERING|FILE_FLAG_WRITE_THROUGH - the machines memory was not consumed by my app and the machine was more usable in general. I'm hoping to duplicate the improvements I've seen but on Linux. On Windows there is the restriction of writing in sector sized pieces, I'm happy with this restriction for the amount of gain I've measured. is there a similar way to do this in Linux?

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  • How to pass variables to slot methods in QT?

    - by Neko
    Hi. I'm making a little chat messenger program, which needs a list of chat channels the user has joined. To represent this list graphically, I have made a list of QPushButtons, which all represent a different channel. These buttons are made with the following method, and that's where my problem kicks in: void Messenger::addToActivePanels(std::string& channel) { activePanelsContents = this->findChild<QWidget *>(QString("activePanelsContents")); pushButton = new QPushButton(activePanelsContents); pushButton->setObjectName("pushButton"); pushButton->setGeometry(QRect(0, 0, 60, 60)); pushButton->setText(""); pushButton->setToolTip(QString(channel.c_str())); pushButton->setCheckable(true); pushButton->setChecked(false); connect(pushButton, SIGNAL(clicked()), this, SLOT(switchTab(channel))); } (activePanelContents is a QWidget that holds the list.) The point is that each button should call the switchTab(string& tabname) method when clicked, including the specific channel's name as variable. This implementation doesn't work though, and I haven't been able to find out how to properly do this, even after reading several pages on it on the internet. Can anybody please tell me how to do this? It'd be greatly appreciated, as always. :)

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  • How can multiple variables be passed to a function cleanly in C?

    - by aquanar
    I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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  • Creating serializeable unique compile-time identifiers for arbitrary UDT's.

    - by Endiannes
    I would like a generic way to create unique compile-time identifiers for any C++ user defined types. for example: unique_id<my_type>::value == 0 // true unique_id<other_type>::value == 1 // true I've managed to implement something like this using preprocessor meta programming, the problem is, serialization is not consistent. For instance if the class template unique_id is instantiated with other_type first, then any serialization in previous revisions of my program will be invalidated. I've searched for solutions to this problem, and found several ways to implement this with non-consistent serialization if the unique values are compile-time constants. If RTTI or similar methods, like boost::sp_typeinfo are used, then the unique values are obviously not compile-time constants and extra overhead is present. An ad-hoc solution to this problem would be, instantiating all of the unique_id's in a separate header in the correct order, but this causes additional maintenance and boilerplate code, which is not different than using an enum unique_id{my_type, other_type};. A good solution to this problem would be using user-defined literals, unfortunately, as far as I know, no compiler supports them at this moment. The syntax would be 'my_type'_id; 'other_type'_id; with udl's. I'm hoping somebody knows a trick that allows implementing serialize-able unique identifiers in C++ with the current standard (C++03/C++0x), I would be happy if it works with the latest stable MSVC and GNU-G++ compilers, although I expect if there is a solution, it's not portable.

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  • own drawImage / drawLine in OpenGL

    - by Chrise
    I'm implementing some native 2D-draw functions in my graphics engine for android, but now there's another question coming up, when I observe the performance of my program. At the moment I'm implementing a drawLine/drawImage function. In summary, there are following different values for drawing each different line / image: the color the alpha value the width of the line rotation (only for images) size/scale (also for images) blending method (subrtract, add, normal-alpha) Now, when an imageLine is drawn, I put the CPU-calculated vertex-positions and uv-values for 6 vertices (2 triangles), into a Floatbuffer and draw it immediately with drawArrays, after passing information for drawing (color,alpha, etc.) via uniforms to the shader. When I draw an image, the pre-set VBO is directly drawn after passing information. The first fact I recognized, is: of course drawing Images is much faster, than imagelines (beacuse of VBOs), but also: I cannot pre-put vertex-data into a VBO for imageLines, because imageLines have no static shape like normal images (varying linelength, varying linewidth and the vertex positions of x1,y1 and x2,y2 change too often) That's why I use a normal Floatbuffer, instead of a VBO. So my question is: What's the best way for managing images, and other 2D-graphics functions. For me it's some kind of important, that the user of the engine is able to draw as many images/2D graphics as possible, without loosing to much performance. You can find the functions for drawing images, imagelines, rects, quads, etc. here: https://github.com/Chrise55/LLama3D/blob/master/Llama3DLibrary/src/com/llama3d/object/graphics/image/ImageBase.java Here an example how it looks with many images (testing artificial neural networks), it works fine, but already little bit slow with that many images... :(

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  • .NET port with Java's Map, Set, HashMap

    - by Nikos Baxevanis
    I am porting Java code in .NET and I am stuck in the following lines that (behave unexpectedly in .NET). Java: Map<Set<State>, Set<State>> sets = new HashMap<Set<State>, Set<State>>(); Set<State> p = new HashSet<State>(); if (!sets.containsKey(p)) { ... } The equivalent .NET code could possibly be: IDictionary<HashSet<State>, HashSet<State>> sets = new Dictionary<HashSet<State>, HashSet<State>>(); HashSet<State> p = new HashSet<State>(); if (!sets.containsKey(p)) { /* (Add to a list). Always get here in .NET (??) */ } However the code comparison fails, the program think that "sets" never contain Key "p" and eventually results in OutOfMemoryException. Perhaps I am missing something, object equality and identity might be different between Java and .NET. I tried implementing IComparable and IEquatable in class State but the results were the same. Edit: What the code does is: If the sets does not contain key "p" (which is a HashSet) it is going to add "p" at the end of a LinkedList. The State class (Java) is a simple class defined as: public class State implements Comparable<State> { boolean accept; Set<Transition> transitions; int number; int id; static int next_id; public State() { resetTransitions(); id = next_id++; } // ... public int compareTo(State s) { return s.id - id; } public boolean equals(Object obj) { return super.equals(obj); } public int hashCode() { return super.hashCode(); }

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  • How to **delete-protect** a file or folder on Windows Server 2003 and onwards using C#/Vb.Net?

    - by Steve Johnson
    Hi all, Is it possible to delete-protect a file/folder using Registry or using a custom written Windows Service in C#? Using Folder Permissions it is possible, but i am looking for a solution that even restricts the admin from deleting specific folders. The requirement is that the administrator must not be easily track the nature of protection and/or may not be able to avert it easily. Obviously all administrators will be able to revert the procedure if the technique is clearly understood. Like folder Permissions/OwnerShip Settings can easily be reset by an administrator. SO that is not an option. Folder protection software can easily be uninstalled and show clear indication that a particular folder is protected by some special kind of software. SO that too is not an option. Most antivirus programs protect folders and files in Program Dir. Windows itself doesnt allow certain files such as registry files in c:\windows\system32\config to not even copied. Such a protection is desired for folders which allowse to read and write to files but not allow deletion. Similar functionality is desired. The protection has to seemless and invisible. I do not want to use any protection features like FolderLock and Invisible secrets/PC Security and Desktop password etc. Moreover, the solution has to be something other than folder encryption. The solution has to be OS-native so ** that it may implemented ** pro grammatically using C#/VB.Net. Please help. Thanks

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