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  • C -- Basic Struct questions

    - by Ryan Yu
    So I'm trying to learn C right now, and I have some basic struct questions I'd like to clear up: Basically, everything centers around this snippet of code: #include <stdio.h> #include <stdlib.h> #define MAX_NAME_LEN 127 typedef struct { char name[MAX_NAME_LEN + 1]; unsigned long sid; } Student; /* return the name of student s */ const char* getName (const Student* s) { // the parameter 's' is a pointer to a Student struct return s->name; // returns the 'name' member of a Student struct } /* set the name of student s If name is too long, cut off characters after the maximum number of characters allowed. */ void setName(Student* s, const char* name) { // 's' is a pointer to a Student struct | 'name' is a pointer to the first element of a char array (repres. a string) s->name = name; } /* return the SID of student s */ unsigned long getStudentID(const Student* s) { // 's' is a pointer to a Student struct return s->sid; } /* set the SID of student s */ void setStudentID(Student* s, unsigned long sid) { // 's' is a pointer to a Student struct | 'sid' is a 'long' representing the desired SID s->sid = sid; } I've commented up the code in an attempt to solidify my understanding of pointers; I hope they're all accurate. So anyway, I have a feeling that setName and setStudentID aren't correct, but I'm not exactly sure why. Can someone explain? Thanks!

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  • iterators to range of elements in a vector whose attributes have specific value

    - by user1801173
    I have a vector of objects and I want to return the range of elements whose attribute have a specific value. This is the structure: class A { public: std::vector<B*> vec_; pair<vector<B*>::iterator, vector<B*>::iterator> getElements(unsigned int attr_val); unsigned int name() { return name_; } private: unsigned int name_; }; class B { public: unsigned int attr() { return attr_; } A* source() { return source_; } B* dest() { return dest_; } private: A* source_; B* dest_; unsigned int attr_; }; The vector vec_; is already sorted by attr_ and dest_-name() (in that order). Now I want to return all elements, whose attr_ is equal to attr_val. What is the appropriate stl algorithm (or is there even a vector member function?) to implement getElements(unsigned int attr_val) ? Thanks for help.

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  • How is the C++ synthesized move constructor affected by volatile and virtual members?

    - by user1827766
    Look at the following code: struct node { node(); //node(const node&); //#1 //node(node&&); //#2 virtual //#3 ~node (); node* volatile //#4 next; }; main() { node m(node()); //#5 node n=node(); //#6 } When compiled with gcc-4.6.1 it produces the following error: g++ -g --std=c++0x -c -o node.o node.cc node.cc: In constructor node::node(node&&): node.cc:3:8: error: expression node::next has side-effects node.cc: In function int main(): node.cc:18:14: note: synthesized method node::node(node&&) first required here As I understand the compiler fails to create default move or copy constructor on line #6, if I uncomment either line #1 or #2 it compiles fine, that is clear. The code compiles fine without c++0x option, so the error is related to default move constructor. However, what in the node class prevents default move constructor to be created? If I comment any of the lines #3 or #4 (i.e. make the destructor non-virtual or make data member non-volatile) it compiles again, so is it the combination of these two makes it not to compile? Another puzzle, line #5 does not cause an compilation error, what is different from line #6? Is it all specific for gcc? or gcc-4.6.1?

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  • Silverlight Binding - Binds when item is added but doesn't get updates.

    - by dw
    Hello, I'm sorta at a loss to why this doesn't work considering I got it from working code, just added a new level of code, but here's what I have. Basically, when I bind the ViewModel to a list, the binding picks up when Items are added to a collection. However, if an update occurs to the item that is bound, it doesn't get updated. Basically, I have an ObservableCollection that contains a custom class with a string value. When that string value gets updated I need it to update the List. Right now, when I debug, the list item does get updated correctly, but the UI doesn't reflect the change. If I set the bound item to a member variable and null it out then reset it to the right collection it will work, but not desired behavior. Here is a mockup of the code, hopefully someone can tell me where I am wrong. Also, I've tried implementing INofityPropertyChanged at every level in the code below. public class Class1 { public string ItemName; } public class Class2 { private Class2 _items; private Class2() //Singleton { _items = new ObservableCollection<Class1>(); } public ObservableCollection<Class1> Items { get { return _items; } internal set { _items = value; } } } public class Class3 { private Class2 _Class2Instnace; private Class3() { _Class2Instnace = Class2.Instance; } public ObservableCollection<Class1> Items2 { get {return _Class2Instnace.Items; } } } public class MyViewModel : INofityPropertyChanged { private Class3 _myClass3; private MyViewModel() { _myClass3 = new Class3(); } private BindingItems { get { return _myClass3.Items2; } // Binds when adding items but not when a Class1.ItemName gets updated. } }

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  • Specializing function templates outside class temp. definition - what is the correct way of doing t

    - by LoudNPossiblyRight
    I am attempting to specialize a function template that is a member of a template class. The two of them have different template parameters. The template function specialization inside the temp. class definition is never called and the one func. spec. outside the class definition does not even compile. Should i expect this to work in the first place, and if so, what do i have to change in this code to both compile and make it work correctly: using VS2010 #include<iostream> using namespace std; template <typename T> class klass{ public: template <typename U> void func(const U &u){ cout << "I AM A TEMPLATE FUNC" << endl; } //THIS NEVER GETS CALLED !!! template <> void klass<T>::func(const string &s){ cout << "I AM A STRING SPECIALIST" << endl; } }; //THIS SPECIALIZATION WILL NOT COMPILE !!! template <typename T> template <> void klass<T>::func(const double &s){ cout << "I AM A DOUBLE SPECIALIST" << endl; } int main(){ double d = 3.14159265; klass<int> k; k.func(1234567890); k.func("string"); k.func(3.14159265); return 0; }

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  • crash when using stl vector at instead of operator[]

    - by Jamie Cook
    I have a method as follows (from a class than implements TBB task interface - not currently multithreading though) My problem is that two ways of accessing a vector are causing quite different behaviour - one works and the other causes the entire program to bomb out quite spectacularly (this is a plugin and normally a crash will be caught by the host - but this one takes out the host program as well! As I said quite spectacular) void PtBranchAndBoundIterationOriginRunner::runOrigin(int origin, int time) const // NOTE: const method { BOOST_FOREACH(int accessMode, m_props->GetAccessModes()) { // get a const reference to appropriate vector from member variable // map<int, vector<double>> m_rowTotalsByAccessMode; const vector<double>& rowTotalsForAccessMode = m_rowTotalsByAccessMode.find(accessMode)->second; if (origin != 129) continue; // Additional debug constrain: I know that the vector only has one non-zero element at index 129 m_job->Write("size: " + ToString(rowTotalsForAccessMode.size())); try { // check for early return... i.e. nothing to do for this origin if (!rowTotalsForAccessMode[origin]) continue; // <- this works if (!rowTotalsForAccessMode.at(origin)) continue; // <- this crashes } catch (...) { m_job->Write("Caught an exception"); // but its not an exception } // do some other stuff } } I hate not putting in well defined questions but at the moment my best phrasing is : "WTF?" I'm compiling this with Intel C++ 11.0.074 [IA-32] using Microsoft (R) Visual Studio Version 9.0.21022.8 and my implementation of vector has const_reference operator[](size_type _Pos) const { // subscript nonmutable sequence #if _HAS_ITERATOR_DEBUGGING if (size() <= _Pos) { _DEBUG_ERROR("vector subscript out of range"); _SCL_SECURE_OUT_OF_RANGE; } #endif /* _HAS_ITERATOR_DEBUGGING */ _SCL_SECURE_VALIDATE_RANGE(_Pos < size()); return (*(_Myfirst + _Pos)); } (Iterator debugging is off - I'm pretty sure) and const_reference at(size_type _Pos) const { // subscript nonmutable sequence with checking if (size() <= _Pos) _Xran(); return (*(begin() + _Pos)); } So the only difference I can see is that at calls begin instead of simply using _Myfirst - but how could that possibly be causing such a huge difference in behaviour?

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  • Is locking on the requested object a bad idea?

    - by Quick Joe Smith
    Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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  • C++ iterator and const_iterator problem for own container class

    - by BaCh
    Hi there, I'm writing an own container class and have run into a problem I can't get my head around. Here's the bare-bone sample that shows the problem. It consists of a container class and two test classes: one test class using a std:vector which compiles nicely and the second test class which tries to use my own container class in exact the same way but fails miserably to compile. #include <vector> #include <algorithm> #include <iterator> using namespace std; template <typename T> class MyContainer { public: class iterator { public: typedef iterator self_type; inline iterator() { } }; class const_iterator { public: typedef const_iterator self_type; inline const_iterator() { } }; iterator begin() { return iterator(); } const_iterator begin() const { return const_iterator(); } }; // This one compiles ok, using std::vector class TestClassVector { public: void test() { vector<int>::const_iterator I=myc.begin(); } private: vector<int> myc; }; // this one fails to compile. Why? class TestClassMyContainer { public: void test(){ MyContainer<int>::const_iterator I=myc.begin(); } private: MyContainer<int> myc; }; int main(int argc, char ** argv) { return 0; } gcc tells me: test2.C: In member function ‘void TestClassMyContainer::test()’: test2.C:51: error: conversion from ‘MyContainer::iterator’ to non-scalar type ‘MyContainer::const_iterator’ requested I'm not sure where and why the compiler wants to convert an iterator to a const_iterator for my own class but not for the STL vector class. What am I doing wrong?

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  • Question on Split usage in Perl

    - by Nano HE
    Hello. I wrote an small script to use Split() as this, use strict; use warnings; use Data::Dumper; my $fh = \*DATA; while(my $line = <$fh>) { my @values = split(':', $line); foreach my $val (@values) { print "$val\n"; } } __DATA__ 1 : Hello World String10 : NO : A1B2,B3 11 : Hello World String11 : YES : A11B2,B3,B14,B25 A1B2,B3 and A11B2,B3 are characters form like Only One Letter A and One or Two Number 2, 3, 14,25 etc then concatenated with Only One Letter B and one or two Numbers like 2, 3, 14,25. etc Now out put as this 1 Hello World String10 NO A1B2,B3 11 Hello World String11 YES A11B2,B3,B14,B25 How can I hold the last array member from @values and made concatenation and out put as this. 1 Hello World String1 NO A1B2,A1B3 11 Hello World String11 YES A11B2,A11B3,A11B14,A11B25 Appreciated for your comments and replies. [update] My out put need the concatenation followed the rule. A and one or two numbers and joined by B and one or two numbers split by ,

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  • PDO closeCursor Error

    - by Metropolis
    Hey Everyone, I currently have a database layer that I wrote myself and I have been using it now for over a year without any problems. The database class uses PDO, and there are two different databases that I regularly connect to (MySQL and MS SQL). The MS SQL database is used for Accpac accounting storage, and the MySQL database is used for everything else. In one of the MySQL databases I have all of the dsn's listed which I use to create the string I need to connect to the MS SQL databases. I have a new program I am trying to write which I am taking employee data from one of the MySQL databases, and using the employee ID to get the employee's information from the MS SQL database. For some reason, whenever I run the program it will get through about 1200 records (out of 11k) and then crash with an error like the following, Fatal error: Call to a member function closeCursor() on a non-object I have tried moving the loops around in many different ways, and I have tried manually closing the connections by setting the database handle to null. Nothing I do seems to work. Thanks for any help! Metropolis

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  • Automatically converting an A* into a B*

    - by Xavier Nodet
    Hi, Suppose I'm given a class A. I would like to wrap pointers to it into a small class B, some kind of smart pointer, with the constraint that a B* is automatically converted to an A* so that I don't need to rewrite the code that already uses A*. I would therefore want to modify B so that the following compiles... struct A { void foo() {} }; template <class K> struct B { B(K* k) : _k(k) {} //operator K*() {return _k;} //K* operator->() {return _k;} private: K* _k; }; void doSomething(A*) {} void test() { A a; A* pointer_to_a (&a); B<A> b (pointer_to_a); //b->foo(); // I don't need those two... //doSomething(b); B<A>* pointer_to_b (&b); pointer_to_b->foo(); // 'foo' : is not a member of 'B<K>' doSomething(pointer_to_b); // 'doSomething' : cannot convert parameter 1 from 'B<K> *' to 'A *' } Note that B inheriting from A is not an option (instances of A are created in factories out of my control)... Is it possible? Thanks.

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  • C++ variable to const expression

    - by user1344784
    template <typename Real> class A{ }; template <typename Real> class B{ }; //... a few dozen more similar template classes class Computer{ public slots: void setFrom(int from){ from_ = from; } void setTo(int to){ to_ = to; } private: template <int F, int T> void compute(){ using boost::fusion::vector; using boost::fusion::at_c; vector<A<float>, B<float>, ...> v; at_c<from_>(v).operator()(at_c<to_>(v)); //error; needs to be const-expression. }; This question isn't about Qt, but there is a line of Qt code in my example. The setFrom() and setTo() are functions that are called based on user selection via the GUI widget. The root of my problem is that 'from' and 'to' are variables. In my compute member function I need to pick a type (A, B, etc.) based on the values of 'from' and 'to'. The only way I know how to do what I need to do is to use switch statements, but that's extremely tedious in my case and I would like to avoid. Is there anyway to convert the error line to a constant-expression?

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  • Problem with inner classes of the same name in Visual C++

    - by starblue
    I have a problem with Visual C++, where apparently inner classes with the same name but in different outer classes are confused. The problem occurs for two layers, where each layer has a listener interface as an inner class. B is a listener of A, and has its own listener in a third layer above it (not shown). The structure of the code looks like this: A.h class A { class Listener { Listener(); virtual ~Listener() = 0; } [...] } B.h class B : public A::Listener { class Listener { Listener(); virtual ~Listener() = 0; } [...] } B.cpp B::Listener::Listener() {} B::Listener::~Listener() {} I get the error B.cpp(49) : error C2509: '{ctor}' : member function not declared in 'B' The C++ compiler for Renesas sh2a has no problem with this, but then it is more liberal than Visual C++ in some other respects, too. If I rename the listener interfaces to have different names the problem goes away, but I'd like to avoid that (the real class names instead of A or B are rather long). Is what I'm doing correct C++, or is the complaint by Visual C++ justified? Is there a way to work around this problem without renaming the listener interfaces?

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  • efficient sort with custom comparison, but no callback function

    - by rob
    I have a need for an efficient sort that doesn't have a callback, but is as customizable as using qsort(). What I want is for it to work like an iterator, where it continuously calls into the sort API in a loop until it is done, doing the comparison in the loop rather than off in a callback function. This way the custom comparison is local to the calling function (and therefore has access to local variables, is potentially more efficient, etc). I have implemented this for an inefficient selection sort, but need it to be efficient, so prefer a quick sort derivative. Has anyone done anything like this? I tried to do it for quick sort, but trying to turn the algorithm inside out hurt my brain too much. Below is how it might look in use. // the array of data we are sorting MyData array[5000], *firstP, *secondP; // (assume data is filled in) Sorter sorter; // initialize sorter int result = sortInit (&sorter, array, 5000, (void **)&firstP, (void **)&secondP, sizeof(MyData)); // loop until complete while (sortIteration (&sorter, result) == 0) { // here's where we do the custom comparison...here we // just sort by member "value" but we could do anything result = firstP->value - secondP->value; }

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  • Optimize INSERT / UPDATE / DELETE operation

    - by clime
    I wonder if the following script can be optimized somehow. It does write a lot to disk because it deletes possibly up-to-date rows and reinserts them. I was thinking about applying something like "insert ... on duplicate key update" and found some possibilities for single-row updates but I don't know how to apply it in the context of INSERT INTO ... SELECT query. CREATE OR REPLACE FUNCTION update_member_search_index() RETURNS VOID AS $$ DECLARE member_content_type_id INTEGER; BEGIN member_content_type_id := (SELECT id FROM django_content_type WHERE app_label='web' AND model='member'); DELETE FROM watson_searchentry WHERE content_type_id = member_content_type_id; INSERT INTO watson_searchentry (engine_slug, content_type_id, object_id, object_id_int, title, description, content, url, meta_encoded) SELECT 'default', member_content_type_id, web_member.id, web_member.id, web_member.name, '', web_user.email||' '||web_member.normalized_name||' '||web_country.name, '', '{}' FROM web_member INNER JOIN web_user ON (web_member.user_id = web_user.id) INNER JOIN web_country ON (web_member.country_id = web_country.id) WHERE web_user.is_active=TRUE; END; $$ LANGUAGE plpgsql; EDIT: Schemas of web_member, watson_searchentry, web_user, web_country: http://pastebin.com/3tRVPPVi. (content_type_id, object_id_int) in watson_searchentry is unique pair in the table but atm the index is not present (there is no use for it). This script should be run at most once a day for full rebuilds of search index.

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  • Finding out the windows group by virtue of which a user is able to access a database in sql server?

    - by Raghu Dodda
    There is a SQL Server 2005 database with mixed-mode authentication. Among others, we have the following logins on the server: our-domain\developers-group-1, and our-domain\developers-group-2 which are AD groups. The our-domain\developer-group-2 is added to the sysadmin role on the server, by virture of which all domain users of that group can access any database as SQL Server implictly maps the sysadmin role to the dbo user in each database. There are two users our-domain\good-user and our-domain\bad-user The issue is the following: Both the good-user and the bad-user have the exact same AD group memberships. They are both members of our-domain\developers-group-1 and our-domain\developers-group-2. The good-user is able to access all the databases, and the bad-user is not. The bad-user is able to login, but he is unable access any databases. By the way, I am the good-user. How do I go about finding out why? Here's what I tried so far: When I do print current_user, I get dbo When I do print system_user, I get my-domain\good-user When I do select * from fn_my_permissions(NULL, 'SERVER'), I see permissions. But if do execute as user='my-domain\good-user'; select * from fn_my_permissions(NULL, 'SERVER'), I dont see any permisisons. And When I do, execute as user='my-domain\bad-user'; select * from fn_my_permissions(NULL, 'SERVER'), I dont see any permisisons. Also, I was wondering if there is a sql command that will tell me, "hey! the current database user is able to access this database because he is a member such-and-such ad-group, which is a login that is mapped to such-and-such user in this database".

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  • system crash after declaring global object of the class

    - by coming out of void
    hi, i am very new to c++. i am getting system crash (not compilation error) in doing following: i am declaring global pointer of class. BGiftConfigFile *bgiftConfig; class BGiftConfigFile : public EftBarclaysGiftConfig { } in this class i am reading tags from xml file. it is crashing system when this pointer is used to retrieve value. i am doing coding for verifone terminal. int referenceSetting = bgiftConfig->getreferencesetting(); //system error getreferencesetting() is member fuction of class EftBarclaysGiftConfig i am confused about behavior of pointer in this case. i know i am doing something wrong but couldn't rectify it. When i declare one object of class locally it retrieves the value properly. BGiftConfigFile bgiftConfig1; int referenceSetting = bgiftConfig1->getreferencesetting(); //working But if i declare this object global it also crashes the system. i need to fetch values at different location in my code so i forced to use someting global. please suggest me how to rectify this problem.

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  • jQuery toggle pushing other elements around... bullies!!

    - by tony noriega
    Ok, so in the left_col of my page, i have a list UL LI that incorporates a jQuery toggle to open a small box, which is "LoginBox". <ul> <li class="members"><a href="/members/signon.asp?userType=member">Members</a></li> <li class="employers"><a href="/employers/signon.asp?userType=employer">Employers</a></li> <li class="providers"><a href="#LoginBox" class="clicker">Providers</a></li> <div class="loginbox" id="LoginBox"> <p>Medical</p> <p>Dental</p> </div> <li class="brokers"><a href="/brokers/signon.asp?userType=broker">Brokers</a></li> </ul> when the jQuery is invoked, it pushes the elements below it down. As expected. What i dont get is that i have an H3 tag below this UL LI which has a background image. The text portion of the H3 gets pushed down, but the background image seems to stay put, and the UL LI that gets pushed down just covers up the background image of the H3. why would the text move, but not the background image itself? here is the H3 style: .sectionmenu h3{ background: url(/_images/h3-triangle.gif) left center no-repeat; color: #000; font-size: 12px; font-weight: bold; padding: 4px 0px 4px 10px; margin: 0; border-bottom:1px dotted #aeaeae;; } and the login box style: .loginbox{ display:none; width:100px; height:50px; margin:0 0 0 77px; }

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  • Tree iterator, can you optimize this any further?

    - by Ron
    As a follow up to my original question about a small piece of this code I decided to ask a follow up to see if you can do better then what we came up with so far. The code below iterates over a binary tree (left/right = child/next ). I do believe there is room for one less conditional in here (the down boolean). The fastest answer wins! The cnt statement can be multiple statements so lets make sure this appears only once The child() and next() member functions are about 30x as slow as the hasChild() and hasNext() operations. Keep it iterative <-- dropped this requirement as the recursive solution presented was faster. This is C++ code visit order of the nodes must stay as they are in the example below. ( hit parents first then the children then the 'next' nodes). BaseNodePtr is a boost::shared_ptr as thus assignments are slow, avoid any temporary BaseNodePtr variables. Currently this code takes 5897ms to visit 62200000 nodes in a test tree, calling this function 200,000 times. void processTree (BaseNodePtr current, unsigned int & cnt ) { bool down = true; while ( true ) { if ( down ) { while (true) { cnt++; // this can/will be multiple statesments if (!current->hasChild()) break; current = current->child(); } } if ( current->hasNext() ) { down = true; current = current->next(); } else { down = false; current = current->parent(); if (!current) return; // done. } } }

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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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  • In Python, how to make data members visible to subclasses if not known when initializing an object ?

    - by LB
    The title is a bit long, but it should be pretty straightforward for someone well-aware of python. I'm a python newbie. So, maybe i'm doing things in the wrong way. Suppose I have a class TreeNode class TreeNode(Node): def __init__(self, name, id): Node.__init__(self, name, id) self.children = [] and a subclass with a weight: class WeightedNode(TreeNode): def __init__(self,name, id): TreeNode.__init__(self, name, id) self.weight = 0 So far, i think I'm ok. Now, I want to add an object variable called father in TreeNode so that WeightedNode has also this member. The problem is that I don't know when initializing the object who is going to be the father. I set the father afterwards with this method in TreeNode : def set_father(self, father_node): self.father = father_node The problem is then when i'm trying to access self.father in Weighted: print 'Name %s Father %s '%(self.name, self.father.name) I obtain: AttributeError: WeightedNode instance has no attribute 'father' I thought that I could make father visible by doing something in TreeNode.__init__ but i wasn't able to find what. How can i do that ? Thanks.

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  • xpath php attributes not working?

    - by Jared
    Getting this error Call to a member function attributes() on a non-object I have found multiple answers to this on SO, but none of them seem to solve my problem? Here is the XML: <Routes> <Route type="source" name="incoming"> </Route> <Routes> Here is the PHP: $doc = new SimpleXMLElement('routingConfig.xml', null, true); class traverseXML { function getData() { global $doc; $routeCount = count($doc -> xpath("Route")); //this value returns correctly $routeArr = array(); for ($i = 1; $i <= $routeCount; $i++) { $name = $doc -> Route[$i] -> attributes() -> name; array_push($routeArr, $name); } return $routeArr; } } $traverseXML = new traverseXML; var_dump($traverseXML -> getData()); I understand what the error means, but how is it a non-object? How do I return the name attribute of Routes/Route[1] ?

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  • Get value of selected field from a dropdown list

    - by 47
    I have this class in my model: class ServiceCharge(models.Model): name = models.CharField(max_length=30) amount = models.PositiveIntegerField() extends_membership = models.BooleanField(default=False) def __unicode__(self): return str(self.name) What I want to have is in the form for charging users a service charge, when a charge is selected from the dropdown menu, the two values for amount and extends_membership are updated on the form depending on the selected charge. My forms.py: class vModelChoiceField(forms.ModelChoiceField): def label_from_instance(self, obj): return "%s" % obj.name class PayServiceChargeForm(PaymentsForm): service_charge = vModelChoiceField(queryset=ServiceCharge.objects.all(), empty_label=" ") class Meta(PaymentsForm.Meta): exclude = ('member', 'payment_type', 'transacted_by', 'description') Then the form template: <table border="0"> <tr> <td><strong>{% trans "Service Charge" %}</strong></td> <td>{{ form.service_charge }}</td> <td><strong>{% trans "Extends Membership" %}</strong></td> <td>{{ form.extends_membership }}</td> </tr> <tr> <td valign="top"><strong>{% trans "Expiry Date" %}</strong></td> <td valign="top">{{ form.expiry_date }}</td> <td valign="top"><strong>{% trans "Amount" %}</strong></td> <td>{{ form.amount }}</td> </tr> </table> I was trying out some jQuery but I got stuck after getting the currently selected charge: <script type="text/javascript"> $(document).ready(function(){ $("#id_service_charge").change(onSelectChange); }); function onSelectChange(){ var selected = $("#id_service_charge option:selected"); var output = ""; if(selected.val() != 0){ charge = selected.val(); .... (update values) .... } } </script>

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  • Doesn't (didn't) Scala have automatically generated setters?

    - by Malvolio
    Google and my failing memory are both giving me hints that it does, but every attempt is coming up dry. class Y { var y = 0 } var m = new Y() m.y_(3) error: value y_ is not a member of Y Please tell me I am doing something wrong. (Also: please tell me what it is I am doing wrong.) EDIT The thing I am not doing wrong, or at least not the only thing I am doing wrong, is the way I am invoking the setter. The following things also fail, all with the same error message: m.y_ // should be a function valued expression m.y_ = (3) // suggested by Google and by Mchl f(m.y_) // where f takes Int => Unit as an argument f(m.y) // complains that I am passing in Int not a function I am doing this all through SimplyScala, because I'm too lazy and impatient to set up Scala on my tiny home machine. Hope it isn't that... And the winner is ... Fabian, who pointed out that I can't have a space between the _ and the =. I thought out why this should be and then it occurred to me: The name of the setter for y is not y_, it is y_= ! Observe: class Y { var y = 0 } var m = new Y() m.y_=(3) m.y res1: Int = 3 m.y_= error: missing arguments for method y_= in class Y; follow this method with `_` if you want to treat it as a partially applied function m.y_= ^ m.y_=_ res2: (Int) => Unit = def four(f : Int => Unit) = f(4) four(m.y_=) m.y res3: Int = 4 Another successful day on StackExchange.

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  • Using a variable in a mysql query, in a C++ MFC program.

    - by D.Gaughan
    Hi, after extensive trawling of the internet I still havent found any solution for this problem. I`m writing a small C++ app that connects to an online database and outputs the data in a listbox. I need to enable a search function using an edit box, but I cant get the query to work while using a variable. My code is: res = mysql_perform_query (conn, "select distinct artist from Artists"); //res = mysql_perform_query (conn, "select album from Artists where artist = ' ' "); while((row = mysql_fetch_row(res)) != NULL){ CString str; UpdateData(); str = ("%s\n", row[0]); UpdateData(FALSE); m_list_control.AddString(str); } the first "res = " line is working fine, but I need the second one to work. I have a member variable m_search_edit set up for the edit box, but any way I try to include it in the sql statement causes errors. eg. res = mysql_perform_query (conn, "select album from Artists where artist = '"+m_search_edit+" ' "); causes this error: error C2664: 'mysql_perform_query' : cannot convert parameter 2 from 'class CString' to 'char *' No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called" And when I convert m_search_edit to a char* it gives me a " Cannot add 2 pointers" error. Any way around this???

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