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  • Ruby getting the diagonal elements in a 2d Array

    - by Calm Storm
    Hi, I was trying some problems with my 2D ruby array and my LOC reduces a lot when I do array slicing. So for example, require "test/unit" class LibraryTest < Test::Unit::TestCase def test_box array = [[1,2,3,4],[3,4,5,6], [5,6,7,8], [2,3,4,5]] puts array[1][2..3] # 5, 6 puts array[1..2][1] # 5, 6, 7, 8 end end I want to know if there is a way to get a diagonal slice? Lets say I want to start at [0,0] and want a diagonal slice of 3. Then I would get elements from [0,0], [1,1], [2,2] and I will get an array like [1,4,7] for example above. Is there any magic one-liner ruby code that can achieve this? 3.times do {some magic stuff?}

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  • PHP login, getting wrong count value from query / fetch array

    - by Chris
    Hello, *EDIT*Thanks to the comments below it has been figured out that the problem lies with the md5, without everything works as it should. But how do i implent the md5 then? I am having some troubles with the following code below to login. The database and register system are already working. The problem lies that it does not find any result at all in the query. IF the count is 0 it should redirect the user to a secured page. But this only works if i write count = 0, but this should be 0 , only if the user name and password is found he should be directed to the secure (startpage) of the site after login. For example root (username) root (password) already exists but i cannot seem to properly login with it. <?php session_start(); if (!empty($_POST["send"])) { $username = ($_POST["username"]); $password = (md5($_POST["password"])); $count = 0; $con = mysql_connect("localhost" , "root", ""); mysql_select_db("testdb", $con); $result = mysql_query("SELECT name, password FROM user WHERE name = '".$username."' AND password = '".$password."' ") or die("Error select statement"); $count = mysql_num_rows($result); if($count > 0) // always goes the to else, only works with >=0 but then the data is not found in the database, hence incorrect { $row = mysql_fetch_array($result); $_SESSION["username"] = $row["name"]; header("Location: StartPage.php"); } else { echo "Wrong login data, please try again"; } mysql_close($con); } ?>

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  • How to use the php fopen() correctly

    - by Jacksta
    I am learning php, trying to use the fopen() function. The php file I am coding is in this directory /domains/xxxxx.com.au/public_html/phpfile.php What path do I specify for the file to be opened, the example I am looking at is based on a server on a pc where this is the file path $filename = "c:/newfile.txt"; not an online server.

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  • C++: Trouble with dependent types in templates

    - by Rosarch
    I'm having trouble with templates and dependent types: namespace Utils { void PrintLine(const string& line, int tabLevel = 0); string getTabs(int tabLevel); template<class result_t, class Predicate> set<result_t> findAll_if(typename set<result_t>::iterator begin, set<result_t>::iterator end, Predicate pred) // warning C4346 { set<result_t> result; return findAll_if_rec(begin, end, pred, result); } } namespace detail { template<class result_t, class Predicate> set<result_t> findAll_if_rec(set<result_t>::iterator begin, set<result_t>::iterator end, Predicate pred, set<result_t> result) { typename set<result_t>::iterator nextResultElem = find_if(begin, end, pred); if (nextResultElem == end) { return result; } result.add(*nextResultElem); return findAll_if_rec(++nextResultElem, end, pred, result); } } Compiler complaints, from the location noted above: warning C4346: 'std::set<result_t>::iterator' : dependent name is not a type. prefix with 'typename' to indicate a type error C2061: syntax error : identifier 'iterator' What am I doing wrong?

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  • Python, lambda, find minimum

    - by qba
    I have foreach function which calls specified function on every element which it contains. I want to get minimum from thise elements but I have no idea how to write lambda or function or even a class that would manage that. Thanks for every help. I use my foreach function like this: o.foreach( lambda i: i.call() ) or o.foreach( I.call ) I don't like to make a lists or other objects. I want to iterate trough it and find min. I manage to write a class that do the think but there should be some better solution than that: class Min: def __init__(self,i): self.i = i def get_min(self): return self.i def set_val(self,o): if o.val < self.i: self.i = o.val m = Min( xmin ) self.foreach( m.set_val ) xmin = m.get_min() Ok, so I suppose that my .foreach method is non-python idea. I should do my Class iterable because all your solutions are based on lists and then everything will become easier. In C# there would be no problem with lambda function like that, so I though that python is also that powerful.

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  • How to enumerate returned rows in SQL?

    - by SilentGhost
    I was wondering if it would be possible to enumerate returned rows. Not according to any column content but just yielding a sequential integer index. E.g. select ?, count(*) as usercount from users group by age would return something along the lines: 1 12 2 78 3 4 4 42

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  • C++ Inheritance and Constructors

    - by DizzyDoo
    Hello, trying to work out how to use constructors with an inherited class. I know this is very much wrong, I've been writing C++ for about three days now, but here's my code anyway: clientData.h, two classes, ClientData extends Entity : #pragma once class Entity { public: int x, y, width, height, leftX, rightX, topY, bottomY; Entity(int x, int y, int width, int height); ~Entity(); }; class ClientData : public Entity { public: ClientData(); ~ClientData(); }; and clientData.cpp, which contains the functions: #include <iostream> #include "clientData.h" using namespace std; Entity::Entity(int x, int y, int width, int height) { this->x = x; this->y = y; this->width = width; this->height = height; this->leftX = x - (width/2); this->rightX = x + (width/2); this->topY = y - (height/2); this-bottomY = y + (height/2); } Entity::~Entity() { cout << "Destructing.\n"; } ClientData::ClientData() { cout << "Client constructed."; } ClientData::~ClientData() { cout << "Destructing.\n"; } and finally, I'm creating a new ClientData with: ClientData * Data = new ClientData(32,32,32,16); Now, I'm not surprised my compiler shouts errors at me, so how do I pass the arguments to the right classes? The first error (from MVC2008) is error C2661: 'ClientData::ClientData' : no overloaded function takes 4 arguments and the second, which pops up whatever changes I seem to make is error C2512: 'Entity' : no appropriate default constructor available Thanks.

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  • DB fields not showing up in association custom queries?

    - by Kevin
    I have a notification list that the user can select different show options for different kinds of notifications along with how many results are returned. I'm keeping them in the user model because I want the custom sort to stay with the user between sessions. Here is the association in my user model: has_many :notifications, :class_name => "Notification", :foreign_key => "user_id", :conditions => ["won = ? and lost = ? and paid = ?", self.prefs_won, self.prefs_lost, self.prefs_paid], :limit => self.prefs_results.to_s But when I use the above code, Rails throws me an "unknown method" error for self.prefs_won. It is definitely a field in my database and set as a boolean value, but Rails can't find it... what's the problem?

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  • C++: Question about freeing memory

    - by Martijn Courteaux
    On Learn C++, they wrote this to free memory: int *pnValue = new int; // dynamically allocate an integer *pnValue = 7; // assign 7 to this integer delete pnValue; pnValue = 0; My question is: "Is the last statement needed to free the memory correctly, completly?" I thought that the pointer *pnValue was still on the stack and new doesn't make any sense to the pointer. And if it is on the stack it will be cleaned up when the application leaves the scope (where the pointer is declared in), isn't it?

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  • Long variable names

    - by RaouL
    Lets say i have a variable that contains the number of search engine names in a file, what would you name it? number_of_seach_engine_names search_engine_name_count num_search_engines engines engine_names other name? The first name describes what the variable contains precisely, but isn't it too long?, any advice for choosing variable names? especially how to shorten a name that is too long or what kind of abbreviations to use?

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  • Type signature "Maybe a" doesn't like "Just [Event]"

    - by sisif
    I'm still learning Haskell and need help with the type inference please! Using packages SDL and Yampa I get the following type signature from FRP.Yampa.reactimate: (Bool -> IO (DTime, Maybe a)) and I want to use it for: myInput :: Bool -> IO (DTime, Maybe [SDL.Event]) myInput isBlocking = do event <- SDL.pollEvent return (1, Just [event]) ... reactimate myInit myInput myOutput mySF but it says Couldn't match expected type `()' against inferred type `[SDL.Event]' Expected type: IO (DTime, Maybe ()) Inferred type: IO (DTime, Maybe [SDL.Event]) In the second argument of `reactimate', namely `input' In the expression: reactimate initialize input output process I thought Maybe a allows me to use anything, even a SDL.Event list? Why is it expecting Maybe () when the type signature is actually Maybe a? Why does it want an empty tuple, or a function taking no arguments, or what is () supposed to be?

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  • Codeigniter: how to track activity w/o using multiple db rows?

    - by Kevin Brown
    I need to track the completion of tasks for users. I started by having a row called "first_login", "profile_complete", "other_thing_complete", etc... I'd like to combine these all into one row "activity_state". I just don't know how to properly store data in this field, and how to retrieve it. What kind of field should it be, and how should I read/write to it?

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  • Simple check authentication decorator in Python + Pylons

    - by ensnare
    I'd like to write a simple decorator that I can put above functions in my controller to check authentication and re-direct to the login page if the current user is not authenticated. What is the best way to do this? Where should the decorator go? How should I pass cookie info to the decorator? Sample code is greatly appreciated. Thank you!

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  • Java: ListA.addAll(ListB) fires NullPointerException?

    - by HH
    The err part is Capitalized in the code, it also comes in foreaching. Because of the abstract list, it cannot be initialized, declaration is in a static field. The lists have the same type. import java.util.*; public class Test { public static final List<String> highPrio = Arrays.asList("*","/"); public static List<String> ops; public static void main(String[] args) { //ERROR HERE, why do it throw nullPointer? ops.addAll(highPrio); for(String s : ops) { System.out.println(s); } } }

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  • Stop overlooking minor details

    - by Mark Lubin
    Compared to most people on this site I am admittedly a novice. I wanted to get some advice from the pros on how to avoid making stupid errors in your code. Is there anyone else who had the problem when they were first starting out of missing some detail that causes big problems? Are there any habits or behaviors that helped you over come this.

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  • If you could remove one feature of php ti help newbies what would it be?

    - by Chris
    If you could remove one feature from PHP so as to discourage, prevent or otherwise help stop newer programmers develop bad habits or practices, or, to stop them falling into traps that might hinder their development skills what would it be and why? Now, before the votes to close it's not as open-ended as you might think. I'm not asking purely what is the worst feature or what feature would you really like to remove purely arbitrarily. Yes, there may not be one correct answer but I suspect there will be many similar answers which will provide me with a good idea of things I might be doing wrong, even inadvertently.

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  • C++ STL: Trouble with string iterators

    - by Rosarch
    I'm making a simple command line Hangman game. void Hangman::printStatus() { cout << "Lives remaining: " << livesRemaining << endl; cout << getFormattedAnswer() << endl; } string Hangman::getFormattedAnswer() { return getFormattedAnswerFrom(correctAnswer.begin(), correctAnswer.end()); } string Hangman::getFormattedAnswerFrom(string::const_iterator begin, string::const_iterator end) { return begin == end? "" : displayChar(*begin) + getFormattedAnswerFrom(++begin, end); } char Hangman::displayChar(const char c) { return c; } (Eventually, I'll change this so displayChar() displays a - or a character if the user has guessed it, but for simplicity now I'm just returning everything.) When I build and run this from VS 2010, I get a popup box: Debug Assertion Failed! xstring Line: 78 Expression: string iterator not dereferenceable What am I doing wrong?

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  • How to iterate over function arguments

    - by Jack
    I have a Python function accepting several string arguments def foo(a, b, c): and concatenating them in a string. I want to iterate over all function arguments to check they are not None. How it can be done? Is there a quick way to convert None to ""? Thanks.

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  • Python Class Variables Question

    - by zyq524
    I have some doubt about python's class variables. As my understanding, if I define a class variable, which is declared outside the init() function, this variable will create only once as a static variable in C++. This seems right for some python types, for instance, dict and list type, but for those base type, e.g. int,float, is not the same. For example: class A: dict1={} list1=list() int1=3 def add_stuff(self, k, v): self.dict1[k]=v self.list1.append(k) self.int1=k def print_stuff(self): print self.dict1,self.list1,self.int1 a1 = A() a1.add_stuff(1, 2) a1.print_stuff() a2=A() a2.print_stuff() The output is: {1: 2} [1] 1 {1: 2} [1] 3 I understand the results of dict1 and list1, but why does int1 behavior different?

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  • Several modules in a package importing one common module

    - by morpheous
    I am writing a python package. I am using the concept of plugins - where each plugin is a specialization of a Worker class. Each plugin is written as a module (script?) and spawned in a separate process. Because of the base commonality between the plugins (e.g. all extend a base class 'Worker'), The plugin module generally looks like this: import commonfuncs def do_work(data): # do customised work for the plugin print 'child1 does work with %s' % data In C/C++, we have include guards, which prevent a header from being included more than once. Do I need something like that in Python, and if yes, how may I make sure that commonfuncs is not 'included' more than once?

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  • linked list problem (with insert)

    - by JohnWong
    The problem appears with the insert function that I wrote. 3 conditions must work, I tested b/w 1 and 2, b/w 2 and 3 and as last element, they worked. But b/w 3 and 4, it did not work. It only display up to the new added record, and did not show the fourth element. Efficiency is not my concern here (not yet). Please guide me through this debug process. Thank you very much. #include<iostream> #include<string> using namespace std; struct List // we create a structure called List { string name; string tele; List *nextAddr; }; void populate(List *); void display(List *); void insert(List *); int main() { const int MAXINPUT = 3; char ans; List * data, * current, * point; // create two pointers data = new List; current = data; for (int i = 0; i < (MAXINPUT - 1); i++) { populate(current); current->nextAddr = new List; current = current->nextAddr; } // last record we want to do it sepeartely populate(current); current->nextAddr = NULL; cout << "The current list consists of the following data records: " << endl; display(data); // now ask whether user wants to insert new record or not cout << "Do you want to add a new record (Y/N)?"; cin >> ans; if (ans == 'Y' || ans == 'y') { /* To insert b/w first and second, use point as parameter between second and third uses point->nextAddr between third and fourth uses point->nextAddr->nextAddr and insert as last element, uses current instead */ point = data; insert(()); display(data); } return 0; } void populate(List *data) { cout << "Enter a name: "; cin >> data->name; cout << "Enter a phone number: "; cin >> data->tele; return; } void display(List *content) { while (content != NULL) { cout << content->name << " " << content->tele; content = content->nextAddr; cout << endl; // we skip to next line } return; } void insert(List *last) { List * temp = last->nextAddr; //save the next address to temp last->nextAddr = new List; // now modify the address pointed to new allocation last = last->nextAddr; populate(last); last->nextAddr = temp; // now link all three together, eg 1-NEW-2 return; }

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  • Normal C++ code in Qt doesnt build and run

    - by Nick
    Hello. I am using Qt under linux, if it matters. I ran successfully under Geany (a simple c++ compiler) the following: //my first program in C++ Hello World! include using namespace std; int main () {cout << "Hello World!"; return 0;} I opened Qt source file and copied the exact same code and i can't build or run. Thank you for your responses to this simple problem.

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  • How to do a random-and-unique generator?

    - by javaLearner.java
    I already wrote a random generator which take arguments a and b, where a is minimun and b is maximum value, like this randomGenerator(int a, int b) What I want to do next is: Using a loop, then generate unique number from a to b. Example: I want to have 8 unique numbers, int a = 1; int b = 10; int value; If I do the loop, there is a high % that same number will appear more than once. Any idea how to do it? My own way is: while(int i <= 8){ randomGenerator(a,b); // if value is not in array, then insert into array } I am stuck at the comment part. Is there any way to check if a variable is exists in an array?

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