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  • Delete last line in txt file

    - by user3658127
    I wrote a foreach loop for my datagridview to write all rows to txt file. I have a problem as it adds 2 empty lines at the end, as 1 row is full of empty cells after adding/reading to datagrid view. Is there any way to omit the last line or delete it in txt? foreach (DataGridViewRow item in this.DB.Rows) { foreach (DataGridViewCell item2 in item.Cells) { if(item2.Value != null) filewrite.Write(item2.Value.ToString() + " "); } filewrite.WriteLine(""); }

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  • making html table columns optionally sortable

    - by jdamae
    I have an html table that is populated from a text file, formatted and semi colon separated. I would like the user to have the option of sorting alphabetically with either of the columns when clicking on the column name (header). How do I do this in php?? Or is there another way of doing this? Thanks for your help. Sample raw data/input looks like this: TYPE=abc;PART=georgetown;FILE=goog_abc.dat.2010122211.gz TYPE=xyz;PART=ucny;FILE=aol_xyz.dat.2010122209.gz Php code for table: $lines = preg_split('~\s*[\r\n]+\s*~', file_get_contents('/temp/tab.txt')); foreach($lines as $i => $line) { $pairs = explode(';', $line); foreach($pairs as $pair) { list($column, $value) = explode('=', $pair, 2); $columns[$column] = true; $rows[$i][$column] = $value; } } $columns = array_keys($columns); echo '<table><thead><tr>'; foreach($columns as $column) { echo '<th>'.$column.'</th>'; } echo '</tr></thead><tbody>'; foreach ($rows as $row) { echo '<tr>'; foreach($columns as $column){ echo '<td>'.$row[$column].'</td>'; } echo '</tr>'; } echo '</tbody></table>';

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  • why does entity framework+mysql provider enumeration returns partial results with no exceptions

    - by Freddy Rios
    I'm trying to make sense of a situation I have using entity framework on .net 3.5 sp1 + MySQL 6.1.2.0 as the provider. It involves the following code: Response.Write("Products: " + plist.Count() + "<br />"); var total = 0; foreach (var p in plist) { //... some actions total++; //... other actions } Response.Write("Total Products Checked: " + total + "<br />"); Basically the total products is varying on each run, and it isn't matching the full total in plist. Its varies widely, from ~ 1/5th to half. There isn't any control flow code inside the foreach i.e. no break, continue, try/catch, conditions around total++, anything that could affect the count. As confirmation, there are other totals captured inside the loop related to the actions, and those match the lower and higher total runs. I don't find any reason to the above, other than something in entity framework or the mysql provider that causes it to end the foreach when retrieving an item. The body of the foreach can have some good variation in time, as the actions involve file & network access, my best shot at the time is that when the .net code takes beyond certain threshold there is some type of timeout in the underlying framework/provider and instead of causing an exception it is silently reporting no more items for enumeration. Can anyone give some light in the above scenario and/or confirm if the entity framework/mysql provider has the above behavior? Update: I can't reproduce the behavior by using Thread.Sleep in a simple foreach in a test project, not sure where else to look for this weird behavior :(.

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  • Hiding a LinkButton in DataList

    - by sanfra1983
    Hi someone can tell me how to hide a LinkButton inside a DataList? I've tried to do this but I do not work: protected void Page_PreRender(object sender, EventArgs e) { foreach (var item in listanews) { DataList container = dlgestionenews; if (string.IsNullOrEmpty(item.IdNews)) { DataListItem itemdatalist = null; foreach (DataListItem itemdl in container.Items) { foreach (Control control in itemdatalist.Controls) { if (control.GetType().FullName == "LinkButton") { ((LinkButton)control).Visible = false; } } } } } } Thanks!

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  • How can i iterate through QListWidget items and work with each item?

    - by Hossein
    In CSharp its as simple as writting : listBox1.Items.Add("Hello"); listBox1.Items.Add("There"); foreach (string item in listBox1.Items ) { MessageBox.Show(item.ToString()); } and i can easily add different objects to a list box and then retrieve them using foreach. I tried the same approach in Qt 4.8.2 but it seems they are different.though they look very similar at first.I found that Qt supports foreach so i went on and tried something like : foreach(QListWidgetItem& item,ui->listWidget->items()) { item.setTextColor(QColor::blue()); } which failed clearly.It says the items() needs a parameter which confuses me.I am trying to iterate through the ListBox itself, so what does this mean? I tried passing the ListBox object as the parameter itself this again failed too: foreach(QListWidgetItem& item,ui->listWidget->items(ui->listWidget)) { item.setTextColor(QColor::blue()); } So here are my questions: How can I iterate through a QListWidget items in Qt? Can i store objects as items in QListWidgets like C#? How can i convert an object in QListWidgets to string(C#s ToString counter part in Qt) ? (suppose i want to use a QMessagBox instead of that setTextColor and want to print out all string items in the QlistWidget.)

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  • Find inner arrays in nested arrays

    - by 50ndr33
    I have a nested array in PHP: array ( '0' => "+5x", '1' => array ( '0' => "+", '1' => "(", '2' => "+3", '3' => array ( '0' => "+", '1' => "(", '2' => array ( // I want to find this one. '0' => "+", '1' => "(", '2' => "+5", '3' => "-3", '4' => ")" ), '3' => "-3", '4' => ")" ), '4' => ")" ) ); I need to process the innermost arrays here, the one with the comment: "I want to find this one." Is there a function for that? I have thought about doing (written as an idea, not as correct PHP): foreach ($array as $id => $value) { if ($value is array) { $name = $id; foreach ($array[$id] as $id_2 => $value_2) { if ($value_2 is array) { $name .= "." . $id_2; foreach ($array[$id][$id_2] as $id_3 => $value_3) { if ($value_3 is array) { $name .= "." . $id_3; foreach ($array[$id][$id_2][$id_3] as $id_4 => $value_4) { if ($value_4 is array) { $name .= "." . $id_4; foreach [and so it goes on]; } else { $listOfInnerArrays[] = $name; break; } } } else { $listOfInnerArrays[] = $name; break; } } } else { $listOfInnerArrays[] = $name; break; } } } } So what it does is it makes $name the current key in the array. If the value is an array, it goes into it with foreach and adds "." and the id of the array. So we would in the example array end up with: array ( '0' => "1.3.2", ) Then I can process those values to access the innner arrays. The problem is that the array that I'm trying to find the inner arrays of is dynamic and made of a user input. (It splits an input string where it finds + or -, and puts it in a separate nested array if it contains brackets. So if the user types a lot of brackets, there will be a lot of nested arrays.) Therefore I need to make this pattern go for 20 times down, and still it will only catch 20 nested arrays no matter what. Is there a function for that, again? Or is there a way to make it do this without my long code? Maybe make a loop make the necessary number of the foreach pattern and run it through eval()? Long answer to J. Bruni: <?php $liste = array ( '0' => "+5x", '1' => array ( '0' => "+", '1' => "(", '2' => "+3", '3' => array ( '0' => "+", '1' => "(", '2' => array ( '0' => "+", '1' => "(", '2' => "+5", '3' => "-3", '4' => ")" ), '3' => "-3", '4' => ")" ), '4' => ")" ) ); function find_deepest( $item, $key ) { echo "0"; if ( !is_array( $item ) ) return false; foreach( $item as $sub_item ) { if ( is_array( $sub_item ) ) return false; } echo "1"; print_r( $item ); return true; } array_walk_recursive( $liste, 'find_deepest' ); echo "<pre>"; print_r($liste); ?> I wrote echo 0 and 1 to see what the script did, and here is the output: 00000000000000 Array ( [0] => +5x [1] => Array ( [0] => + [1] => ( [2] => +3 [3] => Array ( [0] => + [1] => ( [2] => Array ( [0] => + [1] => ( [2] => +5 [3] => -3 [4] => ) ) [3] => -3 [4] => ) ) [4] => ) ) )

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  • Better name needed for applying a function on elements of a container

    - by stefaanv
    I have a container class (containing a multi-index container) for which I have a public "foreach" member-function, so users can pass a functor to apply on all elements. While implementing, I had a case where the functor should only be applied to some elements of a range in the container, so I overloaded the foreach, to pass some valid range. Now, in some cases, it was worthwhile to stop on a certain condition, so practically, I let the foreach stop based on the return-value of the function. I'm pleased with how the system works, but I have one concern: How should a "foreach" on a range, with stop conditions be called? Anyone knows a generic, clear and concise name?

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  • passing multiple queries to view with codeigniter

    - by LvS
    I am trying to build a forum with Codeigniter. So far i have the forums themselves displayed and the threads displayed, based on the creating dynamic news tutorial. But that is 2 different pages, i need to obviously display them into one page, like this: Forum 1 - thread 1 - thread 2 - thread 3 Forum 2 - thread 1 - thread 2 etc. And then the next step is obviously to display all the posts in a thread. Most likely with some pagination going on. But that is for later. For now i have the forum controller (slimmed version): <?php class Forum extends CI_Controller { public function __construct() { parent::__construct(); $this->load->model('forum_model'); $this->lang->load('forum'); $this->lang->load('dutch'); } public function index() { $data['forums'] = $this->forum_model->get_forums(); $data['title'] = $this->lang->line('title'); $data['view'] = $this->lang->line('view'); $this->load->view('templates/header', $data); $this->load->view('forum/index', $data); $this->load->view('templates/footer'); } public function view($slug) { $data['forum_item'] = $this->forum_model->get_forums($slug); if (empty($data['forum_item'])) { show_404(); } $data['title'] = $data['forum_item']['title']; $this->load->view('templates/header', $data); $this->load->view('forum/view', $data); $this->load->view('templates/footer'); } } ?> And the forum_model (also slimmed down) <?php class Forum_model extends CI_Model { public function __construct() { $this->load->database(); } public function get_forums($slug = FALSE) { if ($slug === FALSE) { $query= $this->db->get('forum'); return $query->result_array(); } $query = $this->db->get_where('forum', array('slug' => $slug)); return $query->row_array(); } public function get_threads($forumid, $limit, $offset) { $query = $this->db->get_where('thread', array('forumid', $forumid), $limit, $offset); return $query->result_array(); } } ?> And the view file <?php foreach ($forums as $forum_item): ?> <h2><?=$forum_item['title']?></h2> <div id="main"> <?=$forum_item['description']?> </div> <p><a href="forum/<?php echo $forum_item['slug'] ?>"><?=$view?></a></p> <?php endforeach ?> Now that last one, i would like to have something like this: <?php foreach ($forums as $forum_item): ?> <h2><?=$forum_item['title']?></h2> <div id="main"> <?=$forum_item['description']?> </div> <?php foreach ($threads as $thread_item): ?> <h2><?php echo $thread_item['title'] ?></h2> <p><a href="thread/<?php echo $thread_item['slug'] ?>"><?=$view?></a></p> <?php endforeach ?> <?php endforeach ?> But the question is, how do i get the model to return like a double query to the view, so that it contains both the forums and the threads within each forum. I tried to make a foreach loop in the get_forum function, but when i do this: public function get_forums($slug = FALSE) { if ($slug === FALSE) { $query= $this->db->get('forum'); foreach ($query->row_array() as $forum_item) { $thread_query=$this->get_threads($forum_item->forumid, 50, 0); } return $query->result_array(); } $query = $this->db->get_where('forum', array('slug' => $slug)); return $query->row_array(); } i get the error A PHP Error was encountered Severity: Notice Message: Trying to get property of non-object Filename: models/forum_model.php Line Number: 16 I hope anyone has some good tips, thanks! Lenny *EDIT*** Thanks for the feedback. I have been puzzling and this seems to work now :) $query= $this->db->get('forum'); foreach ($query->result() as $forum_item) { $forum[$forum_item->forumid]['title']=$forum_item->title; $thread_query=$this->db->get_where('thread', array('forumid' => $forum_item->forumid), 20, 0); foreach ($thread_query->result() as $thread_item) { $forum[$forum_item->forumid]['thread'][]=$thread_item->title; } } return $forum; } What is now next, is how to display this multidimensional array in the view, with foreach statements.... Any suggestions ? Thanks

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  • PHP: documentElemnt->childNodes warning

    - by jun
    $xml = file_get_contents(example.com); $dom = new DomDocument(); $dom->loadXML($xml); $items = $dom->documentElement; foreach($items->childNodes as $item) { $childs = $item->childNodes; foreach($childs as $i) { echo $i->nodeValue . "<br />"; } } Now I get this warning in every 2nd foreach: Warning: Invalid argument supplied for foreach() in file_example.php on line 14 Please help guys. Thanks!

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  • PHP: documentElement->childNodes warning

    - by jun
    $xml = file_get_contents(example.com); $dom = new DomDocument(); $dom->loadXML($xml); $items = $dom->documentElement; foreach($items->childNodes as $item) { $childs = $item->childNodes; foreach($childs as $i) { echo $i->nodeValue . "<br />"; } } Now I get this warning in every 2nd foreach: Warning: Invalid argument supplied for foreach() in file_example.php on line 14 Please help guys. Thanks!

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  • Big O Complexity of a method

    - by timeNomad
    I have this method: public static int what(String str, char start, char end) { int count=0; for(int i=0;i<str.length(); i++) { if(str.charAt(i) == start) { for(int j=i+1;j<str.length(); j++) { if(str.charAt(j) == end) count++; } } } return count; } What I need to find is: 1) What is it doing? Answer: counting the total number of end occurrences after EACH (or is it? Not specified in the assignment, point 3 depends on this) start. 2) What is its complexity? Answer: the first loops iterates over the string completely, so it's at least O(n), the second loop executes only if start char is found and even then partially (index at which start was found + 1). Although, big O is all about worst case no? So in the worst case, start is the 1st char & the inner iteration iterates over the string n-1 times, the -1 is a constant so it's n. But, the inner loop won't be executed every outer iteration pass, statistically, but since big O is about worst case, is it correct to say the complexity of it is O(n^2)? Ignoring any constants and the fact that in 99.99% of times the inner loop won't execute every outer loop pass. 3) Rewrite it so that complexity is lower. What I'm not sure of is whether start occurs at most once or more, if once at most, then method can be rewritten using one loop (having a flag indicating whether start has been encountered and from there on incrementing count at each end occurrence), yielding a complexity of O(n). In case though, that start can appear multiple times, which most likely it is, because assignment is of a Java course and I don't think they would make such ambiguity. Solving, in this case, is not possible using one loop... WAIT! Yes it is..! Just have a variable, say, inc to be incremented each time start is encountered & used to increment count each time end is encountered after the 1st start was found: inc = 0, count = 0 if (current char == start) inc++ if (inc > 0 && current char == end) count += inc This would also yield a complexity of O(n)? Because there is only 1 loop. Yes I realize I wrote a lot hehe, but what I also realized is that I understand a lot better by forming my thoughts into words...

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  • OpenSSL Handshake Failure (14094410) - Erroneous Client Certificate Check from Mobile Phone

    - by Clayton Sims
    I'm running a proxy server through Apache with modssl, which we're using to proxy POSTs from mobile devices to another internal server. This works successfully for most clients, but requests from a specific phone model (Nokia 2690) are showing a bizarre handshake failure. It looks as though OpenSSL is either requesting (or attempting to read an unsolicited) client certificate from the phone (which is especially bizarre because j2me's kssl implementation doesn't support client certs). I've disabled client certificates with the SSLVerifyClient none directive in both the virtual host conf and the modssl conf. The trace from error.log on debug level is (details redacted): [client 41.220.207.10] Connection to child 0 established (server www.myserver.org:443) [info] Seeding PRNG with 656 bytes of entropy [debug] ssl_engine_kernel.c(1866): OpenSSL: Handshake: start [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: before/accept initialization [debug] ssl_engine_io.c(1882): OpenSSL: read 11/11 bytes from BIO#7fe3fbaf17a0 [mem: 7fe3fbaf90d0] (BIO dump follows) [debug] ssl_engine_io.c(1815): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1860): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1882): OpenSSL: read 49/49 bytes from BIO#7fe3fbaf17a0 [mem: 7fe3fbaf90db] (BIO dump follows) [debug] ssl_engine_io.c(1815): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1860): +-------------------------------------------------------------------------+ [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: SSLv3 read client hello A [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: SSLv3 write server hello A [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: SSLv3 write certificate A [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: SSLv3 write server done A [debug] ssl_engine_kernel.c(1874): OpenSSL: Loop: SSLv3 flush data [debug] ssl_engine_io.c(1882): OpenSSL: read 5/5 bytes from BIO#7fe3fbaf17a0 [mem: 7fe3fbaf90d0] (BIO dump follows) [debug] ssl_engine_io.c(1815): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1860): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1882): OpenSSL: read 2/2 bytes from BIO#7fe3fbaf17a0 [mem: 7fe3fbaf90d5] (BIO dump follows) [debug] ssl_engine_io.c(1815): +-------------------------------------------------------------------------+ [debug] ssl_engine_io.c(1860): +-------------------------------------------------------------------------+ [debug] ssl_engine_kernel.c(1879): OpenSSL: Read: SSLv3 read client certificate A [debug] ssl_engine_kernel.c(1898): OpenSSL: Exit: failed in SSLv3 read client certificate A [client 41.220.207.10] SSL library error 1 in handshake (server www.myserver.org:443) [info] SSL Library Error: 336151568 error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure [client 41.220.207.10] Connection closed to child 0 with abortive shutdown (server www.myserver.org:443) I've tried enabling all ciphers and all protocols temporarily with modssl, neither of which seemed to be the issue. The phone should be using RSA_RC4_128_MD5 and SSLv3, all of which are available. Am I missing something more fundamental about what's failing here? It seemed like the certificate request might have been part of a renegotiation failure. I tried enabling SSLInsecureRenegotiation On on the virtual host, in case it was an issue of the phone's SSL not supporting the new protocol, but to no avail. Currently running: Apache/2.2.16 (Ubuntu) mod_ssl/2.2.16 OpenSSL/0.9.8o Apache proxy_html/3.0.1

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  • Debian Squeeze vzquota

    - by benjamin
    Hello, Apparently, I got Debian Squeeze (Debian 6) to work on a VPS using debootstrap and chroot as described here. Subsequent installation of the harden, exim4, mysql-server packages failed partially. Relevant information: insserv: warning: script 'S10vzquota' missing LSB tags and overrides insserv: warning: script is corrupt or invalid: /etc/init.d/../rc6.d/S00vzreboot insserv: warning: script 'vzquota' missing LSB tags and overrides insserv: There is a loop between service vzquota and stop-bootlogd if started insserv: loop involving service stop-bootlogd at depth 2 insserv: loop involving service vzquota at depth 1 insserv: loop involving service rsyslog at depth 1 insserv: Starting vzquota depends on stop-bootlogd and therefore on system facility `$all' which can not be true! insserv: Starting vzquota depends on stop-bootlogd and therefore on system facility `$all' which can not be true! insserv: There is a loop between service vzquota and stop-bootlogd if started insserv: Starting vzquota depends on stop-bootlogd and therefore on system facility `$all' which can not be true! insserv: Starting vzquota depends on stop-bootlogd and therefore on system facility `$all' which can not be true! insserv: exiting now without changing boot order! update-rc.d: error: insserv rejected the script header dpkg: error processing exim4-base (--configure): subprocess installed post-installation script returned error exit status 1 Any suggestions? Keywords: vzquota debian squeeze installation vps, virtual private server.

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  • How to export computers from Active Directory to XML using Powershell?

    - by CoDeRs
    I am trying to create a powershell scripts for Remote Desktop Connection Manager using the active directory module. My first thought was get a list of computers in AD and parse them out into XML format similar to the OU structure that is in AD. I have no problem with that, the below code will work just but not how I wanted. EG # here is a the array $OUs Americas/Canada/Canada Computers/Desktops Americas/Canada/Canada Computers/Laptops Americas/Canada/Canada Computers/Virtual Computers Americas/USA/USA Computers/Laptops Computers Disabled Accounts Domain Controllers EMEA/UK/UK Computers/Desktops EMEA/UK/UK Computers/Laptops Outside Sales and Service/Laptops Servers I wanted to have the basic XML structured like this Americas Canada Canada Computers Desktops Laptops Virtual Computers USA USA Computers Laptops Computers Disabled Accounts Domain Controllers EMEA UK UK Computers Desktops Laptops Outside Sales and Service Laptops Servers However if you run the below it does not nest the next string in the array it only restarts the from the beginning and duplicating Americas Canada Canada Computers Desktops Americas Canada Canada Computers Laptops Americas Canada Canada Computers Virtual Computers Americas USA USA Computers Laptops RDCMGenerator.ps1 #Importing Microsoft`s PowerShell-module for administering ActiveDirectory Import-Module ActiveDirectory #Initial variables $OUs = @() $RDCMVer = "2.2" $userName = "domain\username" $password = "Hashed Password+" $Path = "$env:temp\test.xml" $allComputers = Get-ADComputer -LDAPFilter "(OperatingSystem=*)" -Properties Name,Description,CanonicalName | Sort-Object CanonicalName | select Name,Description,CanonicalName $allOUObjects = $allComputers | Foreach {"$($_.CanonicalName)"} Function Initialize-XML{ ##<RDCMan schemaVersion="1"> $xmlWriter.WriteStartElement('RDCMan') $XmlWriter.WriteAttributeString('schemaVersion', '1') $xmlWriter.WriteElementString('version',$RDCMVer) $xmlWriter.WriteStartElement('file') $xmlWriter.WriteStartElement('properties') $xmlWriter.WriteElementString('name',$env:userdomain) $xmlWriter.WriteElementString('expanded','true') $xmlWriter.WriteElementString('comment','') $xmlWriter.WriteStartElement('logonCredentials') $XmlWriter.WriteAttributeString('inherit', 'None') $xmlWriter.WriteElementString('userName',$userName) $xmlWriter.WriteElementString('domain',$env:userdomain) $xmlWriter.WriteStartElement('password') $XmlWriter.WriteAttributeString('storeAsClearText', 'false') $XmlWriter.WriteRaw($password) $xmlWriter.WriteEndElement() $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('connectionSettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('gatewaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('remoteDesktop') $XmlWriter.WriteAttributeString('inherit', 'None') $xmlWriter.WriteElementString('size','1024 x 768') $xmlWriter.WriteElementString('sameSizeAsClientArea','True') $xmlWriter.WriteElementString('fullScreen','False') $xmlWriter.WriteElementString('colorDepth','32') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('localResources') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('securitySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('displaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteEndElement() } Function Create-Group ($groupName){ #Start Group $xmlWriter.WriteStartElement('properties') $xmlWriter.WriteElementString('name',$groupName) $xmlWriter.WriteElementString('expanded','true') $xmlWriter.WriteElementString('comment','') $xmlWriter.WriteStartElement('logonCredentials') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('connectionSettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('gatewaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('remoteDesktop') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('localResources') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('securitySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('displaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteEndElement() } Function Create-Server ($computerName, $computerDescription) { #Start Server $xmlWriter.WriteStartElement('server') $xmlWriter.WriteElementString('name',$computerName) $xmlWriter.WriteElementString('displayName',$computerDescription) $xmlWriter.WriteElementString('comment','') $xmlWriter.WriteStartElement('logonCredentials') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('connectionSettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('gatewaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('remoteDesktop') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('localResources') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('securitySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteStartElement('displaySettings') $XmlWriter.WriteAttributeString('inherit', 'FromParent') $xmlWriter.WriteEndElement() $xmlWriter.WriteEndElement() #Stop Server } Function Close-XML { $xmlWriter.WriteEndElement() $xmlWriter.WriteEndElement() # finalize the document: $xmlWriter.Flush() $xmlWriter.Close() notepad $path } #Strip out Domain and Computer Name from CanonicalName foreach($OU in $allOUObjects){ $newSplit = $OU.split("/") $rebildOU = "" for($i=1; $i -le ($newSplit.count - 2); $i++){ $rebildOU += $newSplit[$i] + "/" } $OUs += $rebildOU.substring(0,($rebildOU.length - 1)) } #Remove Duplicate OU's $OUs = $OUs | select -uniq #$OUs # get an XMLTextWriter to create the XML $XmlWriter = New-Object System.XMl.XmlTextWriter($Path,$UTF8) # choose a pretty formatting: $xmlWriter.Formatting = 'Indented' $xmlWriter.Indentation = 1 $XmlWriter.IndentChar = "`t" # write the header $xmlWriter.WriteStartDocument() # # 'encoding', 'utf-8' How? # # set XSL statements #Initialize Pre-Defined XML Initialize-XML ######################################################### # Start Loop for each OU-Path that has a computer in it ######################################################### foreach ($OU in $OUs){ $totalGroupName = "" #Create / Reset Total OU-Path Completed $OU.split("/") | foreach { #Split the OU-Path into individual OU's $groupName = "$_" #Current OU $totalGroupName += $groupName + "/" #Total OU-Path Completed $xmlWriter.WriteStartElement('group') #Start new XML Group Create-Group $groupName #Call function to create XML Group ################################################ # Start Loop for each Computer in $allComputers ################################################ foreach($computer in $allComputers){ $computerOU = $computer.CanonicalName #Set the computers OU-Path $OUSplit = $computerOU.split("/") #Create the Split for the OU-Path $rebiltOU = "" #Create / Reset the stripped OU-Path for($i=1; $i -le ($OUSplit.count - 2); $i++){ #Start Loop for OU-Path to strip out the Domain and Computer Name $rebiltOU += $OUSplit[$i] + "/" #Rebuild the stripped OU-Path } if ($rebiltOU -eq $totalGroupName){ #Compare the Current OU-Path with the computers stripped OU-Path $computerName = $computer.Name #Set the computer name $computerDescription = $computerName + " - " + $computer.Description #Set the computer Description Create-Server $computerName $computerDescription #Call function to create XML Server } } } ################################################### # Start Loop to close out XML Groups created above ################################################### $totalGroupName.split("/") | foreach { #Split the if ($_ -ne "" ){ $xmlWriter.WriteEndElement() #End Group } } } Close-XML

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  • Varnish gets in a restart loop and causes the system to lock up; how can I fix?

    - by chrism2671
    Here is an extract from the syslog. Mar 2 14:01:10 ip-10-226-34-17 varnishd[20204]: Child (20205) not responding to ping, killing it. Mar 2 14:01:16 ip-10-226-34-17 varnishd[20204]: Child (20205) not responding to ping, killing it. Mar 2 14:01:16 ip-10-226-34-17 varnishd[20204]: Child (20205) died signal=3 Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: Child cleanup complete Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: child (13224) Started Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: Child (13224) said Closed fds: 4 5 6 10 11 13 14 Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: Child (13224) said Child starts Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: Child (13224) said managed to mmap 536870912 bytes of 536870912 Mar 2 14:01:21 ip-10-226-34-17 varnishd[20204]: Child (13224) said Ready Mar 2 14:01:35 ip-10-226-34-17 varnishd[20204]: Child (13224) not responding to ping, killing it. Mar 2 14:02:10 ip-10-226-34-17 last message repeated 7 times Mar 2 14:03:15 ip-10-226-34-17 last message repeated 13 times Mar 2 14:03:20 ip-10-226-34-17 varnishd[20204]: Child (13224) not responding to ping, killing it. Mar 2 14:05:53 ip-10-226-34-17 varnishd[20204]: Child (13224) not responding to ping, killing it. Mar 2 14:05:53 ip-10-226-34-17 varnishd[20204]: Child (13224) not responding to ping, killing it. Mar 2 14:05:53 ip-10-226-34-17 varnishd[20204]: Child (13224) died signal=3 Mar 2 14:05:53 ip-10-226-34-17 varnishd[20204]: Child cleanup complete Mar 2 14:05:53 ip-10-226-34-17 varnishd[20204]: child (13288) Started I'm not expecting a solution here but any help just to decode what each line is doing would be very instructive. Many thanks!

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  • C++ - getline() keeps reading the same line over and over again for some reason

    - by Jammanuser
    I am wondering WTF my while loop which calls istream& getline ( istream& is, string& str ); keeps reading the same line again. I have the following while loop (nested down several levels of other while loops and if statements) which calls getline, but my output statement which is the first code line in the while loop's block of code tells me it is reading the same line over and over again, which explains why my output file doesn't contain the right data when my program is finished. while (getline(file_handle, buffer_str)) { cout<< buffer_str <<endl; cin.get(); if ((buffer_str.find(';', 0) != string::npos) && (buffer_str.find('\"', 0) != string::npos)) { //we're now at the end of the 'exc' initialiation statement buffer_str.erase(buffer_str.size() - 2, 1); buffer_str += '\n'; for (size_t i = 0; i < pos; i++) { buffer_str += ' '; } buffer_str += "throw(exc);\n"; for (size_t i = 0; i < (pos - 3); i++) { buffer_str += ' '; } buffer_str += '}'; } else if (buffer_str.find(search_str6, 0) != string::npos) { //we're now at the second problem line of the first case buffer_str += " {\n"; output_str += buffer_str; output_str += '\n'; getline(file_handle, buffer_str); //We're now at the beginning of the 'exc' initialiation statement output_str += buffer_str; output_str += '\n'; while (getline(file_handle, buffer_str)) { if ((buffer_str.find(';', 0) != string::npos) && (buffer_str.find('\"', 0) != string::npos)) { //we're now at the end of the 'exc' initialiation statement buffer_str.erase(buffer_str.size() - 2, 1); buffer_str += '\n'; for (size_t i = 0; i < pos; i++) { buffer_str += ' '; } buffer_str += "throw(exc);\n"; for (size_t i = 0; i < (pos - 3); i++) { buffer_str += ' '; } buffer_str += '}'; } output_str += buffer_str; output_str += '\n'; if (buffer_str.find("return", 0) != string::npos) { getline(file_handle, buffer_str); output_str += buffer_str; output_str += '\n'; about_to_break = true; break; //out of this while loop } } } if (about_to_break) { break; //out of the level 3 while loop (execution then goes back up to beginning of level 2 while loop) } output_str += buffer_str; output_str += '\n'; } Because of this problem, my if statement and then my else statement in my loop are not functioning as they should, and it doesn't break out of that loop when it should (though it eventually does break out of it, but I don't know exactly how yet). Anyone have any idea what could be causing this problem?? Thanks in advance.

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  • Game programming basics under Windows

    - by dreta
    I've been trying to learn some Windows programming using the Win32 API. Now, i'm used to working with the OS layer being abstracted away, mostly thanks to libraries like SFML or Allegro. Could you guys help me out and tell me if i'm thinking right here. The place for my gameloop is where i'm reading the messages? while (TRUE) { if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE)) { if (msg.message == WM_QUIT) break ; TranslateMessage (&msg) ; DispatchMessage (&msg) ; } else { //my game loop goes here } } Now the slightly bigger issue, that is, drawing. Do i run my drawing where i normaly do it, inside the game loop after the game logic? Or do i do it when WM_PAIN is being called and just call InvalidateRect (hwnd, NULL, TRUE); when i want to draw? This does feel weird, the WM_PAINT is a queued message, so i don't know for sure when it'll be called. So if i wanted to avoid this, do i just get the device handle inside the game loop and only ValidateRect (hwnd, NULL); in the WM_PAINT case (beside the ValidateRect (hwnd, NULL); called after drawing in the game loop)? Actually, now that i think about it, do i even need WM_PAINT in this situation or can i skip it and let DefWindowProc handle it (does it validate the screen if WM_PAINT isn't processed)? If this is any important, i'm setting up my code for OpenGL.

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  • Messages do not always appear in [catalog].[event_messages] in the order that they occur [SSIS]

    - by jamiet
    This is a simple heads up for anyone doing SQL Server Integration Services (SSIS) development using SSIS 2012. Be aware that messages do not always appear in [catalog].[event_messages] in the order that they occur, observe… In the following query I am looking at a subset of messages in [catalog].[event_messages] and ordering them by [event_message_id]: SELECT [event_message_id],[event_name],[message_time],[message_source_name]FROM   [catalog].[event_messages] emWHERE  [event_message_id] BETWEEN 290972 AND 290982ORDER  BY [event_message_id] ASC--ORDER BY [message_time] ASC Take a look at the two rows that I have highlighted, note how the OnPostExecute event for “Utility GetTargetLoadDatesPerETLIfcName” appears after the OnPreExecute event for “FELC Loop over TargetLoadDates”, I happen to know that this is incorrect because “Utility GetTargetLoadDatesPerETLIfcName” is a package that gets executed by an Execute Package Task prior to the For Each Loop “FELC Loop over TargetLoadDates”: If we order instead by [message_time] then we see something that makes more sense: SELECT [event_message_id],[event_name],[message_time],[message_source_name]FROM   [catalog].[event_messages] emWHERE  [event_message_id] BETWEEN 290972 AND 290982--ORDER BY [event_message_id] ASCORDER  BY [message_time] ASC We can see that the OnPostExecute for “Utility GetTargetLoadDatesPerETLIfcName” did indeed occur before the OnPreExecute event for “FELC Loop over TargetLoadDates”, they just did not get assigned an [event_message_id] in chronological order. We can speculate as to why that might be (I suspect the explanation is something to do with the two executables appearing in different packages) but the reason is not the important thing here, just be aware that you should be ordering by [message_time] rather than [event_message_id] if you want to get 100% accurate insights into your executions. @Jamiet

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  • How can I make smoother upwards/downwards controls in pygame?

    - by Zolani13
    This is a loop I use to interpret key events in a python game. # Event Loop for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() if event.type == pygame.KEYDOWN: if event.key == pygame.K_a: my_speed = -10; if event.key == pygame.K_d: my_speed = 10; if event.type == pygame.KEYUP: if event.key == pygame.K_a: my_speed = 0; if event.key == pygame.K_d: my_speed = 0; The 'A' key represents up, while the 'D' key represents down. I use this loop within a larger drawing loop, that moves the sprite using this: Paddle1.rect.y += my_speed; I'm just making a simple pong game (as my first real code/non-gamemaker game) but there's a problem between moving upwards <= downwards. Essentially, if I hold a button upwards (or downwards), and then press downwards (or upwards), now holding both buttons, the direction will change, which is a good thing. But if I then release the upward button, then the sprite will stop. It won't continue in the direction of my second input. This kind of key pressing is actually common with WASD users, when changing directions quickly. Few people remember to let go of the first button before pressing the second. But my program doesn't accommodate the habit. I think I understand the reason, which is that when I let go of my first key, the KEYUP event still triggers, setting the speed to 0. I need to make sure that if a key is released, it only sets the speed to 0 if another key isn't being pressed. But the interpreter will only go through one event at a time, I think, so I can't check if a key has been pressed if it's only interpreting the commands for a released key. This is my dilemma. I want set the key controls so that a player doesn't have to press one button at a time to move upwards <= downwards, making it smoother. How can I do that?

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  • Avoid duplicate custom post type posts in multiple loops in Wordpress

    - by christinaaa
    I am running two loops with a custom post type of Portfolio (ID of 3). The first loop is for Featured and the second is for the rest. I plan on having more than 3 Featured posts in random order. I would like to have the Featured ones that aren't displaying in the first loop to show up in my second loop. How can I set this up so there are no duplicate posts? <?php /* Template Name: Portfolio */ get_header(); ?> <div class="section-bg"> <div class="portfolio"> <div class="featured-title"> <h1>featured</h1> </div> <!-- end #featured-title --> <div class="featured-gallery"> <?php $args = array( 'post_type' => 'portfolio', 'posts_per_page' => 3, 'cat' => 3, 'orderby' => 'rand' ); $loop = new WP_Query( $args ); while ( $loop->have_posts() ) : $loop->the_post(); ?> <div class="featured peek"> <a href="<?php the_permalink(); ?>"> <h1> <?php $thetitle = $post->post_title; $getlength = strlen($thetitle); $thelength = 40; echo substr($thetitle, 0, $thelength); if ($getlength > $thelength) echo '...'; ?> </h1> <div class="contact-divider"></div> <p><?php the_tags('',' / '); ?></p> <?php the_post_thumbnail('thumbnail', array('class' => 'cover')); ?> </a> </div> <!-- end .featured --> <?php endwhile; ?> </div> <!-- end .featured-gallery --> <div class="clearfix"></div> </div> <!-- end .portfolio --> </div> <!-- end #section-bg --> <div class="clearfix"></div> <div class="section-bg"> <div class="portfolio-gallery"> <?php $args = array( 'post_type' => 'portfolio', 'orderby' => 'rand'); $loop = new WP_Query( $args ); while ( $loop->have_posts() ) : $loop->the_post(); ?> <div class="featured peek"> <a href="<?php the_permalink(); ?>"> <h1> <?php $thetitle = $post->post_title; $getlength = strlen($thetitle); $thelength = 40; echo substr($thetitle, 0, $thelength); if ($getlength > $thelength) echo '...'; ?> </h1> <div class="contact-divider"></div> <p><?php the_tags('',' / '); ?></p> <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail('thumbnail', array('class' => 'cover')); ?></a> </a> </div> <!-- end .featured --> <?php endwhile; ?> <div class="clearfix"></div> </div> <!-- end .portfolio-gallery --> <div class="clearfix"></div> </div> <!-- end #section-bg --> <?php get_footer(); ?> If possible, could the answer outline how to implement it into my existing code? Thank you. :)

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  • Basics of Join Predicate Pushdown in Oracle

    - by Maria Colgan
    Happy New Year to all of our readers! We hope you all had a great holiday season. We start the new year by continuing our series on Optimizer transformations. This time it is the turn of Predicate Pushdown. I would like to thank Rafi Ahmed for the content of this blog.Normally, a view cannot be joined with an index-based nested loop (i.e., index access) join, since a view, in contrast with a base table, does not have an index defined on it. A view can only be joined with other tables using three methods: hash, nested loop, and sort-merge joins. Introduction The join predicate pushdown (JPPD) transformation allows a view to be joined with index-based nested-loop join method, which may provide a more optimal alternative. In the join predicate pushdown transformation, the view remains a separate query block, but it contains the join predicate, which is pushed down from its containing query block into the view. The view thus becomes correlated and must be evaluated for each row of the outer query block. These pushed-down join predicates, once inside the view, open up new index access paths on the base tables inside the view; this allows the view to be joined with index-based nested-loop join method, thereby enabling the optimizer to select an efficient execution plan. The join predicate pushdown transformation is not always optimal. The join predicate pushed-down view becomes correlated and it must be evaluated for each outer row; if there is a large number of outer rows, the cost of evaluating the view multiple times may make the nested-loop join suboptimal, and therefore joining the view with hash or sort-merge join method may be more efficient. The decision whether to push down join predicates into a view is determined by evaluating the costs of the outer query with and without the join predicate pushdown transformation under Oracle's cost-based query transformation framework. The join predicate pushdown transformation applies to both non-mergeable views and mergeable views and to pre-defined and inline views as well as to views generated internally by the optimizer during various transformations. The following shows the types of views on which join predicate pushdown is currently supported. UNION ALL/UNION view Outer-joined view Anti-joined view Semi-joined view DISTINCT view GROUP-BY view Examples Consider query A, which has an outer-joined view V. The view cannot be merged, as it contains two tables, and the join between these two tables must be performed before the join between the view and the outer table T4. A: SELECT T4.unique1, V.unique3 FROM T_4K T4,            (SELECT T10.unique3, T10.hundred, T10.ten             FROM T_5K T5, T_10K T10             WHERE T5.unique3 = T10.unique3) VWHERE T4.unique3 = V.hundred(+) AND       T4.ten = V.ten(+) AND       T4.thousand = 5; The following shows the non-default plan for query A generated by disabling join predicate pushdown. When query A undergoes join predicate pushdown, it yields query B. Note that query B is expressed in a non-standard SQL and shows an internal representation of the query. B: SELECT T4.unique1, V.unique3 FROM T_4K T4,           (SELECT T10.unique3, T10.hundred, T10.ten             FROM T_5K T5, T_10K T10             WHERE T5.unique3 = T10.unique3             AND T4.unique3 = V.hundred(+)             AND T4.ten = V.ten(+)) V WHERE T4.thousand = 5; The execution plan for query B is shown below. In the execution plan BX, note the keyword 'VIEW PUSHED PREDICATE' indicates that the view has undergone the join predicate pushdown transformation. The join predicates (shown here in red) have been moved into the view V; these join predicates open up index access paths thereby enabling index-based nested-loop join of the view. With join predicate pushdown, the cost of query A has come down from 62 to 32.  As mentioned earlier, the join predicate pushdown transformation is cost-based, and a join predicate pushed-down plan is selected only when it reduces the overall cost. Consider another example of a query C, which contains a view with the UNION ALL set operator.C: SELECT R.unique1, V.unique3 FROM T_5K R,            (SELECT T1.unique3, T2.unique1+T1.unique1             FROM T_5K T1, T_10K T2             WHERE T1.unique1 = T2.unique1             UNION ALL             SELECT T1.unique3, T2.unique2             FROM G_4K T1, T_10K T2             WHERE T1.unique1 = T2.unique1) V WHERE R.unique3 = V.unique3 and R.thousand < 1; The execution plan of query C is shown below. In the above, 'VIEW UNION ALL PUSHED PREDICATE' indicates that the UNION ALL view has undergone the join predicate pushdown transformation. As can be seen, here the join predicate has been replicated and pushed inside every branch of the UNION ALL view. The join predicates (shown here in red) open up index access paths thereby enabling index-based nested loop join of the view. Consider query D as an example of join predicate pushdown into a distinct view. We have the following cardinalities of the tables involved in query D: Sales (1,016,271), Customers (50,000), and Costs (787,766).  D: SELECT C.cust_last_name, C.cust_city FROM customers C,            (SELECT DISTINCT S.cust_id             FROM sales S, costs CT             WHERE S.prod_id = CT.prod_id and CT.unit_price > 70) V WHERE C.cust_state_province = 'CA' and C.cust_id = V.cust_id; The execution plan of query D is shown below. As shown in XD, when query D undergoes join predicate pushdown transformation, the expensive DISTINCT operator is removed and the join is converted into a semi-join; this is possible, since all the SELECT list items of the view participate in an equi-join with the outer tables. Under similar conditions, when a group-by view undergoes join predicate pushdown transformation, the expensive group-by operator can also be removed. With the join predicate pushdown transformation, the elapsed time of query D came down from 63 seconds to 5 seconds. Since distinct and group-by views are mergeable views, the cost-based transformation framework also compares the cost of merging the view with that of join predicate pushdown in selecting the most optimal execution plan. Summary We have tried to illustrate the basic ideas behind join predicate pushdown on different types of views by showing example queries that are quite simple. Oracle can handle far more complex queries and other types of views not shown here in the examples. Again many thanks to Rafi Ahmed for the content of this blog post.

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  • C# Performance Pitfall – Interop Scenarios Change the Rules

    - by Reed
    C# and .NET, overall, really do have fantastic performance in my opinion.  That being said, the performance characteristics dramatically differ from native programming, and take some relearning if you’re used to doing performance optimization in most other languages, especially C, C++, and similar.  However, there are times when revisiting tricks learned in native code play a critical role in performance optimization in C#. I recently ran across a nasty scenario that illustrated to me how dangerous following any fixed rules for optimization can be… The rules in C# when optimizing code are very different than C or C++.  Often, they’re exactly backwards.  For example, in C and C++, lifting a variable out of loops in order to avoid memory allocations often can have huge advantages.  If some function within a call graph is allocating memory dynamically, and that gets called in a loop, it can dramatically slow down a routine. This can be a tricky bottleneck to track down, even with a profiler.  Looking at the memory allocation graph is usually the key for spotting this routine, as it’s often “hidden” deep in call graph.  For example, while optimizing some of my scientific routines, I ran into a situation where I had a loop similar to: for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i]); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This loop was at a fairly high level in the call graph, and often could take many hours to complete, depending on the input data.  As such, any performance optimization we could achieve would be greatly appreciated by our users. After a fair bit of profiling, I noticed that a couple of function calls down the call graph (inside of ProcessElement), there was some code that effectively was doing: // Allocate some data required DataStructure* data = new DataStructure(num); // Call into a subroutine that passed around and manipulated this data highly CallSubroutine(data); // Read and use some values from here double values = data->Foo; // Cleanup delete data; // ... return bar; Normally, if “DataStructure” was a simple data type, I could just allocate it on the stack.  However, it’s constructor, internally, allocated it’s own memory using new, so this wouldn’t eliminate the problem.  In this case, however, I could change the call signatures to allow the pointer to the data structure to be passed into ProcessElement and through the call graph, allowing the inner routine to reuse the same “data” memory instead of allocating.  At the highest level, my code effectively changed to something like: DataStructure* data = new DataStructure(numberToProcess); for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i], data); } delete data; Granted, this dramatically reduced the maintainability of the code, so it wasn’t something I wanted to do unless there was a significant benefit.  In this case, after profiling the new version, I found that it increased the overall performance dramatically – my main test case went from 35 minutes runtime down to 21 minutes.  This was such a significant improvement, I felt it was worth the reduction in maintainability. In C and C++, it’s generally a good idea (for performance) to: Reduce the number of memory allocations as much as possible, Use fewer, larger memory allocations instead of many smaller ones, and Allocate as high up the call stack as possible, and reuse memory I’ve seen many people try to make similar optimizations in C# code.  For good or bad, this is typically not a good idea.  The garbage collector in .NET completely changes the rules here. In C#, reallocating memory in a loop is not always a bad idea.  In this scenario, for example, I may have been much better off leaving the original code alone.  The reason for this is the garbage collector.  The GC in .NET is incredibly effective, and leaving the allocation deep inside the call stack has some huge advantages.  First and foremost, it tends to make the code more maintainable – passing around object references tends to couple the methods together more than necessary, and overall increase the complexity of the code.  This is something that should be avoided unless there is a significant reason.  Second, (unlike C and C++) memory allocation of a single object in C# is normally cheap and fast.  Finally, and most critically, there is a large advantage to having short lived objects.  If you lift a variable out of the loop and reuse the memory, its much more likely that object will get promoted to Gen1 (or worse, Gen2).  This can cause expensive compaction operations to be required, and also lead to (at least temporary) memory fragmentation as well as more costly collections later. As such, I’ve found that it’s often (though not always) faster to leave memory allocations where you’d naturally place them – deep inside of the call graph, inside of the loops.  This causes the objects to stay very short lived, which in turn increases the efficiency of the garbage collector, and can dramatically improve the overall performance of the routine as a whole. In C#, I tend to: Keep variable declarations in the tightest scope possible Declare and allocate objects at usage While this tends to cause some of the same goals (reducing unnecessary allocations, etc), the goal here is a bit different – it’s about keeping the objects rooted for as little time as possible in order to (attempt) to keep them completely in Gen0, or worst case, Gen1.  It also has the huge advantage of keeping the code very maintainable – objects are used and “released” as soon as possible, which keeps the code very clean.  It does, however, often have the side effect of causing more allocations to occur, but keeping the objects rooted for a much shorter time. Now – nowhere here am I suggesting that these rules are hard, fast rules that are always true.  That being said, my time spent optimizing over the years encourages me to naturally write code that follows the above guidelines, then profile and adjust as necessary.  In my current project, however, I ran across one of those nasty little pitfalls that’s something to keep in mind – interop changes the rules. In this case, I was dealing with an API that, internally, used some COM objects.  In this case, these COM objects were leading to native allocations (most likely C++) occurring in a loop deep in my call graph.  Even though I was writing nice, clean managed code, the normal managed code rules for performance no longer apply.  After profiling to find the bottleneck in my code, I realized that my inner loop, a innocuous looking block of C# code, was effectively causing a set of native memory allocations in every iteration.  This required going back to a “native programming” mindset for optimization.  Lifting these variables and reusing them took a 1:10 routine down to 0:20 – again, a very worthwhile improvement. Overall, the lessons here are: Always profile if you suspect a performance problem – don’t assume any rule is correct, or any code is efficient just because it looks like it should be Remember to check memory allocations when profiling, not just CPU cycles Interop scenarios often cause managed code to act very differently than “normal” managed code. Native code can be hidden very cleverly inside of managed wrappers

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  • 3D Model not translating correctly (visually)

    - by ChocoMan
    In my first image, my model displays correctly: But when I move the model's position along the Z-axis (forward) I get this, yet the Y-axis doesnt change. An if I keep going, the model disappears into the ground: Any suggestions as to how I can get the model to translate properly visually? Here is how Im calling the model and the terrain in draw(): cameraPosition = new Vector3(camX, camY, camZ); // Copy any parent transforms. Matrix[] transforms = new Matrix[mShockwave.Bones.Count]; mShockwave.CopyAbsoluteBoneTransformsTo(transforms); Matrix[] ttransforms = new Matrix[terrain.Bones.Count]; terrain.CopyAbsoluteBoneTransformsTo(ttransforms); // Draw the model. A model can have multiple meshes, so loop. foreach (ModelMesh mesh in mShockwave.Meshes) { // This is where the mesh orientation is set, as well // as our camera and projection. foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(modelRotation) * Matrix.CreateTranslation(modelPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, modelPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); mesh.Draw(); } //Terrain test foreach (ModelMesh meshT in terrain.Meshes) { foreach (BasicEffect effect in meshT.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = ttransforms[meshT.ParentBone.Index] * Matrix.CreateRotationY(0) * Matrix.CreateTranslation(terrainPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, terrainPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); meshT.Draw(); DrawText(); } base.Draw(gameTime); } Im suspecting that there may be something wrong with how I'm handling my camera. The model rotates fine on its Y-axis.

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  • Obtaining positional information in the IEnumerable Select extension method

    - by Kyle Burns
    This blog entry is intended to provide a narrow and brief look into a way to use the Select extension method that I had until recently overlooked. Every developer who is using IEnumerable extension methods to work with data has been exposed to the Select extension method, because it is a pretty critical piece of almost every query over a collection of objects.  The method is defined on type IEnumerable and takes as its argument a function that accepts an item from the collection and returns an object which will be an item within the returned collection.  This allows you to perform transformations on the source collection.  A somewhat contrived example would be the following code that transforms a collection of strings into a collection of anonymous objects: 1: var media = new[] {"book", "cd", "tape"}; 2: var transformed = media.Select( item => 3: { 4: Media = item 5: } ); This code transforms the array of strings into a collection of objects which each have a string property called Media. If every developer using the LINQ extension methods already knows this, why am I blogging about it?  I’m blogging about it because the method has another overload that I hadn’t seen before I needed it a few weeks back and I thought I would share a little about it with whoever happens upon my blog.  In the other overload, the function defined in the first overload as: 1: Func<TSource, TResult> is instead defined as: 1: Func<TSource, int, TResult>   The additional parameter is an integer representing the current element’s position in the enumerable sequence.  I used this information in what I thought was a pretty cool way to compare collections and I’ll probably blog about that sometime in the near future, but for now we’ll continue with the contrived example I’ve already started to keep things simple and show how this works.  The following code sample shows how the positional information could be used in an alternating color scenario.  I’m using a foreach loop because IEnumerable doesn’t have a ForEach extension, but many libraries do add the ForEach extension to IEnumerable so you can update the code if you’re using one of these libraries or have created your own. 1: var media = new[] {"book", "cd", "tape"}; 2: foreach (var result in media.Select( 3: (item, index) => 4: new { Item = item, Index = index })) 5: { 6: Console.ForegroundColor = result.Index % 2 == 0 7: ? ConsoleColor.Blue : ConsoleColor.Yellow; 8: Console.WriteLine(result.Item); 9: }

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