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• Understanding linear linked list

  - by ArtWorkAD

  Hi, I have some problems understanding the linear linked list data structure. This is how I define a list element: class Node{ Object data; Node link; public Node(Object pData, Node pLink){ this.data = pData; this.link = pLink; } } To keep it simple we say that a list are linked nodes so we do not need to define a class list (recursion principle). My problem is that I am really confused in understanding how nodes are connected, more precisely the sequence of the nodes when we connect them. Node n1 = new Node(new Integer(2), null); Node n2 = new Node(new Integer(1), n1); What is link? Is it the previous or the next element? Any other suggestions to help me understanding this data structure?

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• [app-engine-java-groovy] One-to-Many relationship. Select objects from datastore.

  - by Olexandr

  Hi. I've omitted some code(package declarations, imports, other fields) for shortness. I have here simple One-to-Many relation. It worked fine till this moment. @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class Restaurant implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent(mappedBy = "restaurant") List<RestaurantAddress> addresses = new ArrayList<RestaurantAddress>() } //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class RestaurantAddress implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent Restaurant restaurant } Now i need to get(select) all the Restaurants from DB: def getRestaurantsToExport(final String dst, final int count) { String field = restaurantExportFields[dst] return transactionExecute() { PersistenceManager pm -> Query q = pm.newQuery(Restaurant.class) q.filter = "$field == null" q.setRange(0, count) return q.execute() } } But there are on problem - query gives me 12 restaurants(as in DB) but every Restaurant has 0 Address but in Datastore every Restaurant has minimum 2 addresses. Have anyone the same problem or knows the solution ?

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• textview.selectedRange.location in UITextview show 2147483647

  - by Risma

  hi i have a textview and i want to get the selectedRange.location value from that textview. in the first time when the keyboard appear, the location value always show an integer point such as 110, or others. But if i dissappear the keyboard and then appear the keyboard again, the location value always show 2147483647. What is this 2147483647 mean and how to get the real location value? This is my code in the keyboard will appear method : -(void)keyboardWillAppear:(NSNotification *)notification { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:[[[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue]]; CGRect keyboardEndingUncorrectedFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey ] CGRectValue]; CGRect keyboardEndingFrame = [self.view convertRect:keyboardEndingUncorrectedFrame fromView:nil]; [UIView commitAnimations]; NSRange selectedRange = textview.selectedRange; NSLog(@"selected Range location : %f", selectedRange.location); }

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• Cannot running next process when a variable save no value

  - by bruine

  First, I wanna compare between 2 tables tb_wrapper and tb_summary to get the data in the tb_wrapper that doesn't exist in the tb_summary then save in $link. If I don't get the same data, I want to print the result $link. When I don't get the not same data, I want it to go to another process. Here's the code : $q2 = mysql_query(" SELECT a.doc_url FROM tb_wrapper a LEFT JOIN tb_summary b ON a.doc_name = b.doc_summ WHERE b.doc_summ IS NULL"); while ($row = mysql_fetch_array($q2)){ $link = $row['doc_url']; if (!$link){ include 'next_process.php'; } else { print_r($link); } } it doesn't work. When I don't get the not same data or $link not save a value. table : CREATE TABLE tb1 (`id` int, `doc_name` varchar(100), `doc_url` varchar(50)) } CREATE TABLE tb2 (`id` int, `doc_summ` varchar(100)) }

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• How to format complex chained Linq statements for readibility?

  - by Joan Venge

  I have some code like this: var effects = xElement.Elements ( "Effects" ).Elements ( "Effect" ).Select ( e => new Effect ( ( EffectType ) Enum.Parse ( typeof ( EffectType ), ( string ) e.Elements ( "Type" ).FirstOrDefault ( ) ), e.Elements ( "Options" ).Any ( ) ? e.Elements ( "Options" ).Select ( o => ( object ) o.Elements ( "Option" ).Select ( n => n.Value ).First ( ) ) : null ) ) .ToList ( ); But currently this doesn't look as readable and I am not sure where I should add a new line and/or indent for readability. Any suggestions I could use to make consistent, readable linq blocks?

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• How do I access a DIV from javascript, if ASP.NET mangles its ID?

  - by Rising Star

  I have a web page that contains a "div" element. On the page, there is javascript to reference the div: document.getElementById('divId'). This was working fine until another developer redesigned the page to use an ASP master page. Now, document.getElementById('divId') returns null. It appears that ASP.net prepends some characters to the names of elements within contents forms when you use a master page. How can I know what the id of the div is when the page loads? Update Allow me to give a specific example to clarify the question: My page had a div with ID divNotice. After changing my page to use a master page, I see when I print the source to the page that renders that the div ID is ctl00_ContentPlaceHolder1_divNotice. My question is, how am I supposed to know what the div ID is going to be when the framework is done with it?

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• g_signal_connect error invalid use of member

  - by paultop6

  Hi Guys, More GTK questions, im trying to compile some code and im getting the following error: error: invalid use of member (did you forget the ‘&’ ?) This is comming from the g_signal_connect call: g_signal_connect ((gpointer) Drawing_Area_CPU, "expose-event", G_CALLBACK (graph_expose), NULL); Drawing_Area_CPU is a GtkWidget* and graph_expose is defined as: gboolean graph_expose(GtkWidget *widget, GdkEventExpose *event, gpointer data); So far as i can tell im doing everything right, but still i get this error. Can anyone help please? Regards Paul

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• DataGridView error when set DataSource

  - by user264464

  I got an error when run datagridview.DataSource = dataView; dataview is correct. I can see data inside it when I debug program. I got next error "Object reference not set to an instance of an object." Any Ideas? code: this.datagridview = new System.Windows.Forms.DataGridView(); ... DataSet ds = new DataSet(); XmlReaderSettings settings = new XmlReaderSettings(); StringReader stringReader = new StringReader(retString); XmlReader xmlReader = XmlReader.Create(stringReader, settings); ds.ReadXml(xmlReader); DataView dataView = ds.Tables[0].DefaultView; dataView is not null. I am able to view it when debug

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• SQLite: does data type depend on the quotes?

  - by Septagram

  In SQLite, the datatype of a value is associated with the value itself, not with the column type. So suppose we have a table with an integer primary key "id" and an integer column "some_number". If I do a query like this: INSERT INTO mytable (id, some_number) VALUES (NULL, "1234") Will 123 be inserted as an integer or as string? What consequences it will have later for me, say, when I'm comparing it with other value like "234" (as a number 1234 234, as a string "1234" < "234", right?)?

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• C# Why does this code not show a GUI properly?

  - by Tom

  class Program { static String ChannelName = null; static Form1 f; static void Main() { f = new Form1(); f.Show(); try { MY CODE WHICH CALLS INTO ANOTHER CLASS BUT CANNOT PASS THE GUI INSTANCE AS IT USES REMOTING } } } I know this isnt the best/normal way to do it, but i need to write data to the GUI from a class which has bo instance of the GUI so i was going to call Program.method() and use a function to write to the GUI in program. However when i run the above my GUI displays but with the windows hourglass? Could someone show me a quick fix so that i can still crudely show the GUI, let the application code run and then later write to the GUI?

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• ManyToManyField error when having recursive structure. How to solve it?

  - by luc

  Hello, I have the following table in the model with a recursive structure (a page can have children pages) class DynamicPage(models.Model): name = models.CharField("Titre",max_length=200) parent = models.ForeignKey('self',null=True,blank=True) I want to create another table with manytomany relation with this one: class UserMessage(models.Model): name = models.CharField("Nom", max_length=100) page = models.ManyToManyField(DynamicPage) The generated SQL creates the following constraint: ALTER TABLE `website_dynamicpage` ADD CONSTRAINT `parent_id_refs_id_29c58e1b` FOREIGN KEY (`parent_id`) REFERENCES `website_dynamicpage` (`id`); I would like to have the ManyToMany with the page itself (the id) and not with the parent field. How to modify the model to make the constraint using the id and not the parent? Thanks in advance

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• Windows Phone 7: Making ListBox items change dynamically

  - by Chad La Guardia

  I am working on creating a Windows Phone app that will play a series of sound clips selected from a list. I am using the MVVM (Model View View-Model) Design pattern and have designed a model for my data, along with a view model for my page. Here is what the XAML for the ListBox looks like: <ListBox x:Name="MediaListBox" Margin="0,0,-12,0" ItemsSource="{Binding Media}" SelectionChanged="MediaListBox_SelectionChanged" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch"> <ListBox.ItemTemplate > <DataTemplate> <StackPanel Margin="0,0,0,17" Width="432" Orientation="Horizontal"> <Image Source="../Media/Images/play.png" /> <StackPanel > <TextBlock Text="{Binding Title}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}"/> <TextBlock Text="{Binding ShortDescription}" TextWrapping="Wrap" Margin="12,-6,12,0" Visibility="{Binding ShortDescriptionVisibility}" Style="{StaticResource PhoneTextSubtleStyle}"/> <TextBlock Text="{Binding LongDescription}" TextWrapping="Wrap" Visibility="{Binding LongDescriptionVisibility}" /> <StackPanel> <Slider HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" Visibility="{Binding LongDescriptionVisibility}" ValueChanged="Slider_ValueChanged" LargeChange="0.25" SmallChange="0.05" /> </StackPanel> </StackPanel> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> My question is this: I want to be able to expand and collapse part of the items in the ListBox. As you can see, I have a binding for the visibility. That binding is coming from the MediaModel. However, when I change this property in the ObservableCollection, the page is not updated to reflect this. The ViewModel for this page looks like this: public class ListenPageViewModel : INotifyPropertyChanged { public ListenPageViewModel() { this.Media = new ObservableCollection<MediaModel>; } /// <summary> /// A collection for MediaModel objects. /// </summary> public ObservableCollection<MediaModel> Media { get; private set; } public bool IsDataLoaded { get; private set; } /// <summary> /// Creates and adds the media to their respective collections. /// </summary> public void LoadData() { this.Media.Clear(); this.Media.Add(new MediaModel() { Title = "Media 1", ShortDescription = "Short here.", LongDescription = "Long here.", MediaSource = "/Media/test.mp3", LongDescriptionVisibility = Visibility.Collapsed, ShortDescriptionVisibility = Visibility.Visible }); this.Media.Add(new MediaModel() { Title = "Media 2", ShortDescription = "Short here.", LongDescription = "Long here.", MediaSource = "/Media/test2.mp3", LongDescriptionVisibility = Visibility.Collapsed, ShortDescriptionVisibility = Visibility.Visible }); this.IsDataLoaded = true; } public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(String propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (null != handler) { handler(this, new PropertyChangedEventArgs(propertyName)); } } } The bindings work correctly and I am seeing the data displayed; however, when I change the properties, the list does not update. I believe that this may be because when I change things inside the observable collection, the property changed event is not firing. What can I do to remedy this? I have poked around for some info on this, but many of the tutorials don't cover this kind of behavior. Any help would be greatly appreciated! Thanks Edit: As requested, I have added the MediaModel code: public class MediaModel : INotifyPropertyChanged { public string Title { get; set; } public string ShortDescription { get; set; } public string LongDescription { get; set; } public string MediaSource { get; set; } public Visibility LongDescriptionVisibility { get; set; } public Visibility ShortDescriptionVisibility { get; set; } public MediaModel() { } public MediaModel(string Title, string ShortDescription, string LongDescription, string MediaSource, Visibility LongDescriptionVisibility, Visibility ShortDescriptionVisibility) { this.Title = Title; this.ShortDescription = ShortDescription; this.LongDescription = LongDescription; this.MediaSource = MediaSource; this.LongDescriptionVisibility = LongDescriptionVisibility; this.ShortDescriptionVisibility = ShortDescriptionVisibility; } public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(String propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (null != handler) { handler(this, new PropertyChangedEventArgs(propertyName)); } } } Originally, I did not have this class implement the INotifyPropertyChanged. I did this to see if it would solve the problem. I was hoping this could just be a data object.

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• function to remove duplicate characters in a string

  - by Codenotguru

  The following code is trying to remove any duplicate characters in a string.Iam not sure if the code is right??Can anybody help me with the working of the code i.e whats actually happening when there is a match in characters? public static void removeDuplicates(char[] str) { if (str == null) return; int len = str.length; if (len < 2) return; int tail = 1; for (int i = 1; i < len; ++i) { int j; for (j = 0; j < tail; ++j) { if (str[i] == str[j]) break; } if (j == tail) { str[tail] = str[i]; ++tail; } } str[tail] = 0; }

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• How to Execute Base Class's Method Before Implementors's Method?

  - by DaveDev

  I have the following page public partial class GenericOfflineCommentary : OfflineFactsheetBase { } where OfflineFactsheetBase is defined as public class OfflineFactsheetBase : System.Web.UI.Page { public OfflineFactsheetBase() { this.Load += new EventHandler(this.Page_Load); this.PreInit += new EventHandler(this.Page_PreInit); } protected void Page_PreInit(object sender, EventArgs e) { if (Request.QueryString["data"] != null) { this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]); this.ExtractPageData(); } } } OfflineFactsheetBase has the following virtual method: public virtual void ExtractPageData() { // get stuff relevant to all pages that impmement OfflineFactsheetBase } which is implemented in all pages that impmement OfflineFactsheetBase as follows: public partial class GenericOfflineCommentary : OfflineFactsheetBase { public override void ExtractPageData() { // get stuff relevant to an OfflineCommentary page. } } Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's? edit: I'm trying to avoid having to call base.ExtractPageData() in every implementor. Is this possible?

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• what else to do to establish many-to-many associations in Ruby on Rails? thanks!

  - by john

  Hi, I have two classes and I want to establish a many-to-many assications, here is the code: class Category < ActiveRecord::Base has_and_belongs_to_many :events has_and_belongs_to_many :tips end class Tip < ActiveRecord::Base has_and_belongs_to_many :categories However, I kept getting the following errors and I would appreciate it if some one could educate me what is going wrong: PGError: ERROR: relation "categories_tips" does not exist : SELECT "categories".id FROM "categories" INNER JOIN "categories_tips" ON "categories".id = "categories_tips".category_id WHERE ("categories_tips".tip_id = NULL ) the viewer part: 4: <%= text_field :tip, :title %></label></p> 5: 6: <p><label>Categories<br/> 7: <%= select_tag('categories[]', options_for_select(Category.find(:all).collect {|c| [c.name, c.id] }, @tip.category_ids), :multiple => true ) %></label></p> 8: 9: <p><label>Location<br/> 10: <%= text_field_with_auto_complete :tip, :abstract %></label></p>

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• Breaking out of .emacs script

  - by prosseek

  I use two emacs (Aquamcs and text based emacs) on my Mac. I normally use text based emacs for just editing something, so I don't want to load anything with it. What I came up with is to have the checking code in .emacs to exit/break if it's text based emacs (darwin system but not aquamacs). (when (and (equal system-type 'darwin) (not (boundp 'aquamacs-version))) (exit) ??? (break) ???? ) It seems to work, but I don't know how to break out of .emacs. How to do that? ADDED I just wanted to speed up in loading text based emacs on my mac, and I thought about breaking out as a solution. Based on the helpful answers, I came up with the following code that runs .emacs only when it's not a text based emacs. (setq inhibit-splash-screen t) (unless (null window-system)

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• How to display model popup at first time page load only

  - by Guna Sundari

  I used the following code to display model popup for the first time page load, <script type="text/javascript"> function pageload() { var chkPostBack = '<%= Page.IsPostBack ? "true" : "false" %>'; if (chkPostBack == 'false') { var popup = $find('ModalPopupExtender1'); if (popup != null) { popup.show(); } } } I got the following error, Please help me. The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>).

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• Refactoring method that was previously injected with implement

  - by ryber

  Greetings, I'm trying to override or extend the Element.show() and .hide() methods in mootools in order to add some WAI-Aria toggling. I was trying to use the Class.Refactor() method like this: Element = Class.refactor(Element, { show: function(displayString) { result = this.previous(displayString); // Do my thing return result; }, hide: function() { result = this.previous(); // Do my thing return result; } }); however, this is not working, previous is null and I think the reason is that Mootools injects those methods through Element.implement. So the methods are not native? I have figured out how to completely replace .show and .hide but I would like to retain all of their existing functionality and just add to it. Any ideas?

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• C# GroupJoin effectiveness

  - by bsnote

  without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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• postgres min function performance

  - by wutzebaer

  hi i need the lowest value for runnerId this query: SELECT "runnerId" FROM betlog WHERE "marketId" = '107416794' ; takes 80ms (1968 result rows) this SELECT min("runnerId") FROM betlog WHERE "marketId" = '107416794' ; takes 1600ms is there a faster way to find the minimum, or should i calc the min in my java programm? "Result (cost=100.88..100.89 rows=1 width=0)" " InitPlan 1 (returns $0)" " -> Limit (cost=0.00..100.88 rows=1 width=9)" " -> Index Scan using runneridindex on betlog (cost=0.00..410066.33 rows=4065 width=9)" " Index Cond: ("runnerId" IS NOT NULL)" " Filter: ("marketId" = 107416794::bigint)" CREATE INDEX marketidindex ON betlog USING btree ("marketId" COLLATE pg_catalog."default"); another idea SELECT "runnerId" FROM betlog WHERE "marketId" = '107416794' ORDER BY "runnerId" LIMIT 1 >1600ms SELECT "runnerId" FROM betlog WHERE "marketId" = '107416794' ORDER BY "runnerId" >>100ms how can a limit slow the query down?

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• Checkbox - in Javascript

  - by smiley

  I am working on Edit screen where I am pulling out value from db to check if the checkbox is checked or not. If it is unchecked, it should deselect the checkbox and other controls of this checkbox. In my case the js works perfectly fine. That is if my previous screen has checkbox unchecked, edit screen disables all the values for this checkbox. But it still shows the checkbox is checked in UI(though it is actually checked). Something is wrong with my html code. Can someone please let me know where /how should i modify to display if my checkbox is unchecked? <%chkStatus=list.getCheckbox(); if (chkStatus == null) { chkStatus = ""; } %> <input id="chkbox" type="checkbox" name="chkbox" checked="<%=chkStatus%>" onchange="javascript:enableDisableTextBox();">

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• Query for multiple joins

  - by Shailaja

  i have 3 tables named dataset,dataelem and transformdataelem with column names as below: main.Dataset ------------ datasetID (PK) applicationID main.Dataelem ------------- dataelemID(PK) datasetID(FK) dataelemname biztermID main.Transformdataelem ---------------------- OutputdataelemID InputdataelemID My requirement is: All tables are referenced. Extract all the dataelemId rows from dataelem table where applicationID of dataset table is equal to 1044 and biztermid shud be null. Then whatever resultant dataelemIDs from the above query should be matched with outputdataelemID of Transformdataelem table and we shud get the respective input dataelemId's. Again with these matched inputdataelemID's we shud get the dataelemname's from datelem table.

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• Java - Reg. Ex. File Question

  - by aloh

  I'm grabbing lines from a text file and sifting line by line using regular expressions. I'm trying to search for blank lines, meaning nothing or just whitespace. However, what exactly is empty space? I know that whitespace is \s but what is a line that is nothing at all? null (\0)? newline (\n)? I tried the test harness in the Java tutorial to try and test to see what an empty space is but no luck so far.

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• How to generate all permutations of a string in PHP ?

  - by Johan

  I need an algorithm that return all possible combination of all characters in one string. I've tried: $langd = strlen($input); for($i = 0;$i < $langd; $i++){ $tempStrang = NULL; $tempStrang .= substr($input, $i, 1); for($j = $i+1, $k=0; $k < $langd; $k++, $j++){ if($j > $langd) $j = 0; $tempStrang .= substr($input, $j, 1); } $myarray[] = $tempStrang; } But that only returns the same amount combination as the length of the string. Say the $input is = "hey", the result would be: hey, hye, eyh, ehy, yhe, yeh.

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• What is a cross-platform way to get the current directory?

  - by rubenvb

  I need a cross-platform way to get the current working directory (yes, getcwd does what I want). I thought this might do the trick: #ifdef _WIN32 #include <direct.h> #define getcwd _getcwd // stupid MSFT "deprecation" warning #elif #include <unistd.h> #endif #include <string> #include <iostream> using namespace std; int main() { string s_cwd(getcwd(NULL,0)); cout << "CWD is: " << s_cwd << endl; } I got this reading: _getcwd at MSDN getcwd at Kernel.org getcwd at Apple.com There should be no memory leaks, and is should work on a Mac as well, correct?

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