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  • How to do Linq aggregates when there might be an empty set?

    - by Shaul
    I have a Linq collection of Things, where Thing has an Amount (decimal) property. I'm trying to do an aggregate on this for a certain subset of Things: var total = myThings.Sum(t => t.Amount); and that works nicely. But then I added a condition that left me with no Things in the result: var total = myThings.Where(t => t.OtherProperty == 123).Sum(t => t.Amount); And instead of getting total = 0 or null, I get an error: System.InvalidOperationException: The null value cannot be assigned to a member with type System.Decimal which is a non-nullable value type. That is really nasty, because I didn't expect that behavior. I would have expected total to be zero, maybe null - but certainly not to throw an exception! What am I doing wrong? What's the workaround/fix?

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  • c++ networking issue- retrnsmittion without ccongestion

    - by gln
    I wrote an application in c++ which send data over tcp connection to several machines.as part of the protocol I use in my application, the other side sends hearbeat messages from time to time, then I know that the connection is still alive. now, I want this application to work on 100 machines or more at the same time. but, I see that sometimes I don't get these heartbeat messages although they sent: I see in wireshark that the packet arrived, then my OS doesn't ack on this message, so there are some retransmit without any ack from my OS. if I look in the window size property - I saw that there is no issue in this part. what can be the root cause for this behavior? it is something in my code that I should change? this is my select code: int res = select(fdCount, &readFds, NULL, NULL, NULL ); I'm using server 2008 r2. Please help me! thanks

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  • how use ASP.NET_SessionId cookies to check timeout for 2 different web applications

    - by user553858
    Hi All I am developing 2 web applications based on "ASP.NET_SessionId" cookies to check session timeout and also to logout : protected void Session_Start(object sender, EventArgs e) { if (Context.Session != null) { //check the IsNewSession value, this will tell us if the session has been reset if (Session.IsNewSession) { string cookie = Request.Headers["Cookie"]; // Code that runs when a new session is started if ((null != cookie) && (cookie.IndexOf("ASP.NET_SessionId") >= 0)) { if (Request.QueryString["timeout"] == null || !Request.QueryString["timeout"].ToString().Equals("yes")) Session.Abandon(); Session.Clear(); Response.Redirect("Login.aspx?timeout=yes"); } } } } This works fine for my first application. When implementing the same logic for the 2nd application when I press logout in one application, the second application is redirected to the login page. How can I fix this? Best regards

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  • why there is no power operator in java / c ++?

    - by RanZilber
    While there is such operator - ** in Python , i was wondering why java and c++ havent got one too. It is easy to make one for classes you define in C++ with operator overloading ( and i believe such thing is possible also in java) , but when talking about primitive types such as int, double and so on , you'll have to use library function like Math.power (and usaully have to cast both to double). So - why not define such operator for primitive types ?

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  • In WPF Not Able to Kill Adobe Acrobat Reader

    - by Blam
    Problem with killing Adobe Acrobat Reader Code used to launch the process nativeProcess = new Process(); nativeProcess.StartInfo.FileName = filePath; nativeProcess.Start(); These are Microsoft Office Files or Adobe Acrobat. Code used to kill if (nativeProcess != null) { try { nativeProcess.Kill(); } catch { } } if (nativeProcess != null) { try { nativeProcess = null; } catch { } } My problem is that Adobe Acrobat Reader does not Kill() when the app is running as a Citrix app. If I log on at the Citrix box and run it as a Desktop app then Acrobat Kill() works. Microsoft Office Kills() fine as both a Citrix app and a Deskop app. User can close Acrobat Reader using the X or close

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  • alter mysqldump file before import

    - by julio
    Hi-- I have a mysqldump file created from an earlier version of a product that can't be imported into a new version of the product, since the db structure has changed slightly (mainly altering a column that was NOT NULL DEFAULT 0 to UNIQUE KEY DEFAULT NULL). If I just import the old dump file, it will error out since the column that has default values of 0 now breaks the UNIQUE constraint. It would be easy enough to either manually alter the mysqldump file, or import into a temp table and change it, then copy to the new table. However, is there a way to do this programatically, so it will be repeatable and not manual? (this will need to happen for many instances of this product). I'm thinking something like disabling key constraints for the import, then setting all values that = 0 to NULL, then re-enabling the key constraints? Is this possible? Any help appreciated.

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  • How to retrieve an url parameter in the Zend Framework ?

    - by ismaelsow
    Hello guys ! I'am trying to retrieve an parameter passed in a url using the zend framework. But of course, it is not working ! My code looks like this : Generating the url : <?php echo $this->url(array('controller' => 'poll', 'action' => 'showresults', 'poll_id' => $poll['_id']), null, true) ?> Retrieving the "poll_id" parameter in showresultsAction() : $request = new Zend_Controller_Request_Http(); $poll_id = $request->getParam('poll_id'); The problem is that $poll_id is NULL. When I do a var_dump of $request-getParams(), it is also NULL. I have glanced trough the Zend Framework doc, but it was not very usefull. Any idea ? Thanks !

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  • debugfs_create_file doesn't create file

    - by bala1486
    Hello, I am trying to create a debugfs file using the debugfs_create_file(...). I have written a sample code for this. static int __init mmapexample_module_init(void) { file1 = debugfs_create_file("mmap_example", 0644, NULL, NULL, &my_fops)\ ; printk(KERN_ALERT "Hello, World\n"); if(file1==NULL) { printk(KERN_ALERT "Error occured\n"); } if(file1==-ENODEV) { printk(KERN_ALERT "ENODEV occured\n"); } return 0; } When i ran insmod i could get the Hello, World message but no the error message. So i think the debugfs_create_file worked fine. However i couldn't find any file in /sys/kernel/debug. The folder is there but it is empty. Can anyone help me with this? Thank you... Thanks, Bala

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  • How to handle large table in MySQL ?

    - by Frantz Miccoli
    I've a database used to store items and properties about these items. The number of properties is extensible, thus there is a join table to store each property associated to an item value. CREATE TABLE `item_property` ( `property_id` int(11) NOT NULL, `item_id` int(11) NOT NULL, `value` double NOT NULL, PRIMARY KEY (`property_id`,`item_id`), KEY `item_id` (`item_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; This database has two goals : storing (which has first priority and has to be very quick, I would like to perform many inserts (hundreds) in few seconds), retrieving data (selects using item_id and property_id) (this is a second priority, it can be slower but not too much because this would ruin my usage of the DB). Currently this table hosts 1.6 billions entries and a simple count can take up to 2 minutes... Inserting isn't fast enough to be usable. I'm using Zend_Db to access my data and would really be happy if you don't suggest me to develop any php side part. Thanks for your advices !

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  • discovering files in the FileSystem, through SSIS

    - by cometbill
    I have a folder where files are going to be dropped for importing into my data warehouse. \\server\share\loading_area I have the following (inherited) code that uses xp_cmdshell shivers to call out to the command shell to run the DIR command and insert the resulting filenames into a table in SQL Server. I would like to 'go native' and reproduce this functionality in SSIS. Thanks in advance guys and girls. Here's the code USE MyDatabase GO declare @CMD varchar(500) declare @EXTRACT_PATH varchar(255) set @EXTRACT_PATH = '\\server\share\folder\' create table tmp_FILELIST([FILENUM] int identity(1,1), [FNAME] varchar(100), [FILE_STATUS] varchar(20) NULL CONSTRAINT [DF_FILELIST_FILE_STATUS] DEFAULT ('PENDING')) set @CMD = 'dir ' + @EXTRACT_PATH + '*.* /b /on' insert tmp_FILELIST([FNAME]) exec master..xp_cmdshell @CMD --remove the DOS reply when the folder is empty delete tmp_FILELIST where [FNAME] is null or [FNAME] = 'File Not Found' --Remove my administrative and default/common, files not for importing, such as readme.txt delete tmp_FILELIST where [FNAME] is null or [FNAME] = 'readme.txt'

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  • How do I get a JComponent to resize after calling `setVisible(true)`?

    - by iWerner
    Our application displays a 2D view of our data (mainly maps) and then allows the user to change to a 3D view. The 2D and 3D views are generated by custom C++ code that is SWIG'ed into our Swing GUI and wrapped within a JComponent. These JComponents are then displayed within another parent JComponent. Our problem is that when we change from the 2D to the 3D view and then back to the 2D view, when we resize the window the 2D view does not get resized. The resize events don't get sent to the 2D view. Our application runs under Linux (Fedora 11). We're running Java version 1.6.0_12. Here is some sample code in which I've replaced the 2D view and 3D view with two 2 JButtons, that produces the same behaviour. Once you go to 3D and then back to 2D, resizing the window does not cause the 2D view to be resized. /* TestFrame.java * Compile with: $ javac TestFrame.java * Run with: $ java TestFrame */ import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ComponentEvent; import java.awt.event.ComponentListener; import javax.swing.JButton; public class TestFrame extends javax.swing.JFrame { private boolean mode2D = true; private JButton view2D = null; private JButton view3D = null; private Container parent = null; public TestFrame() { initComponents(); containerPanel.setLayout(new BorderLayout()); view2D = new JButton("2D View"); view2D.addComponentListener(new MyListener("2D VIEW")); containerPanel.add(view2D); } private void changerButtonActionPerformed(java.awt.event.ActionEvent evt) { if (parent == null) { parent = view2D.getParent(); } if (mode2D) { System.out.println("Going from 2D to 3D"); view2D.setVisible(false); if (view3D != null) { view3D.setVisible(true); } else { view3D = new JButton("3D View"); view3D.addComponentListener(new MyListener("3D VIEW")); parent.add(view3D); } ((JButton) evt.getSource()).setText("Change to 2D"); mode2D = false; } else { System.out.println("Going from 3D to 2D"); view3D.setVisible(false); view2D.setVisible(true); ((JButton) evt.getSource()).setText("Change to 3D"); mode2D = true; } } public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new TestFrame().setVisible(true); } }); } private javax.swing.JPanel containerPanel; private javax.swing.JButton changerButton; private class MyListener implements ComponentListener { private String name; public MyListener(String name) { this.name = name; } @Override public void componentHidden(ComponentEvent event) { System.out.println("@@@ [" + name + "] component Hidden"); } @Override public void componentResized(ComponentEvent event) { System.out.println("@@@ [" + name + "] component Resized"); } @Override public void componentShown(ComponentEvent event) { System.out.println("@@@ [" + name + "] component Shown"); } @Override public void componentMoved(ComponentEvent event) { System.out.println("@@@ [" + name + "] component Moved"); } }; @SuppressWarnings("unchecked") private void initComponents() { containerPanel = new javax.swing.JPanel(); changerButton = new javax.swing.JButton(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); containerPanel.setBorder(new javax.swing.border.MatteBorder(null)); javax.swing.GroupLayout containerPanelLayout = new javax.swing.GroupLayout(containerPanel); containerPanel.setLayout(containerPanelLayout); containerPanelLayout.setHorizontalGroup( containerPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 374, Short.MAX_VALUE) ); containerPanelLayout.setVerticalGroup( containerPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 239, Short.MAX_VALUE) ); changerButton.setText("Change to 3D"); changerButton.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { changerButtonActionPerformed(evt); } }); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addContainerGap() .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(containerPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) .addComponent(changerButton)) .addContainerGap()) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addContainerGap() .addComponent(containerPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) .addComponent(changerButton) .addContainerGap()) ); pack(); } } (My apologies for the Netbeans generated GUI code) I should mention that when we call parent.remove(view2D) and parent.add(view3D) to change the views the X Windows ID of our 3D view changes and we're unable to get our 3D view back. Therefore parent.remove(view2D) and parent.add(view3D) is not really a solution and we have to call setVisible(false) and setVisible(true) on the JComponents that contain our 2D and 3D views in order to hide and show them. Any help will be greatly appreciated.

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  • Is this a correct implementation of singleton C++?

    - by Kamal
    class A{ static boost::shared_ptr<A> getInstance(){ if(pA==NULL){ pA = new A(); } return boost::shared_ptr(pA); } //destructor ~A(){ delete pA; pA=NULL; } private: A(){ //some initialization code } //private assigment and copy constructors A(A const& copy); // Not Implemented A& operator=(A const& copy); // Not Implemented static A* pA; }; A* A::pA = NULL;

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  • error string list handle in C#

    - by Chelsea_cole
    Same namespace: 2 forms. public class Account //frm1 { public string Username; public string Password; } public class ListAcc { public static List<Account> UserList; } private void button1_Click(object sender, EventArgs e) { List<Account> UserList = new List<Account>(); Account acc = new Account(); acc.Username = textBox1.Text; acc.Password = textBox2.Text; UserList.Add(acc); } private void button2_Click(object sender, EventArgs e) //frm2 { string p = frmDangky.ListAcc.UserList[0].Username; // null ->error string p = frmDangky.ListAcc.UserList[0].Password; // null ->error } Someone help me? :( why my string is NULL???????? The textBox is not empty... Thanks!

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  • How do I obtain the version information for my Windows Service programmatically

    - by user302004
    I need to obtain the version of my Windows service programmatically and store it in a string. Then, I'll append the version to my display name and service name in the ProjectInstaller class. Right now I'm getting an empty string and I'm having trouble debugging my setup project. Here's my current code: string version = null; try { Assembly exeAssembly = Assembly.GetEntryAssembly(); Type attrType = typeof(AssemblyFileVersionAttribute); object[] attributes = exeAssembly.GetCustomAttributes(attrType, false); if (attributes.Length 0) { AssemblyFileVersionAttribute verAttr = (AssemblyFileVersionAttribute)attributes[0]; if (verAttr != null) { version = verAttr.Version; } } } catch { } if (version == null) { version = string.empty; }

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  • How can I deal with the cargo-cult programming attitude?

    - by Aivar
    I have some computer science students in a compulsory introductory programming course who see programming language as a set of magic spells, which must be cast in order to achieve some effect (instead of seeing it as a flexible medium for expressing their idea of solution). They tend to copy-paste code from previous, similar-looking assignments without considering the essence of the problem. Can anyone recommend some exercises or analogies to make these students more confident that they can, and should, understand the structure and meaning of each piece of code they write?

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  • How do I make this Query against EF Efficient?

    - by dudeNumber4
    Using EF4. Assume I have this: IQueryable<ParentEntity> qry = myRepository.GetParentEntities(); Int32 n = 1; What I want to do is this, but EF can't compare against null. qry.Where( parent => parent.Children.Where( child => child.IntCol == n ) != null ) What works is this, but the SQL it produces (as you would imagine) is pretty inefficient: qry.Where( parent => parent.Children.Where( child => child.IntCol == n ).FirstOrDefault().IntCol == n ) How can I do something like the first comparison to null that won't be generating nested queries and so forth?

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  • Force column order, Excel data table

    - by Chris
    I have a Excel Workbook that I use as a report template. I change the datasource on each pivot and datatable in a C# app. When I change the datatable datasource it tweeks the columns. Is there a way to force the column order? private void RefreshRawData(string dataSource, string connection) { xl._Worksheet ws = (xl._Worksheet)xlTemplate.Worksheets["Raw Data"]; xl.ListObject table = ws.ListObjects["Table_ExternalData_1"]; xl.QueryTable qt = table.QueryTable; qt.CommandText = dataSource; qt.Connection = GetExcelConnectionString((string)qt.Connection); qt.BackgroundQuery = false; qt.Refresh(m); Marshal.ReleaseComObject(ws); Marshal.ReleaseComObject(table); Marshal.ReleaseComObject(qt); ws = null; table = null; qt = null; }

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  • Can I avoid repeating myself in this situation (Java)

    - by UltimateGuy
    if (openFile == null) { new AppFileDialog().chooseFile("Save", appFrame); } if (openFile == null) { return; } Here I need to check to see if the user has already chosen a file. If not, they are given a prompt to. If the file is still null, the function returns without saving. The problem is the two identical if statements, can I avoid it? I take DRY very seriously, but at the same time KISS. Ideally the two go hand in hand, but in a situation like this, it seems they are mutually exclusive.

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  • In SQL, what does Group By mean without Count(*), or Sum(), Max(), avg(), ..., and what are some use

    - by Jian Lin
    In SQL, if we use Group By without Count(*) or Sum(), etc, then the result is as follows: mysql> select * from sentGifts; +--------+------------+--------+------+---------------------+--------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | +--------+------------+--------+------+---------------------+--------+ | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | | 2 | 2010-04-24 | 123 | 4568 | 2010-04-24 01:56:04 | 100 | | 3 | 2010-04-24 | 123 | NULL | NULL | 1 | | 4 | 2010-04-24 | NULL | 111 | 2010-04-24 03:10:42 | 2 | | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | | 6 | 2010-04-24 | 11 | 222 | 2010-04-24 03:54:49 | 6 | | 7 | 2010-04-24 | 1 | 2 | 2010-04-24 03:58:45 | 6 | +--------+------------+--------+------+---------------------+--------+ 7 rows in set (0.00 sec) mysql> select *, count(*) from sentGifts group by whenSent; +--------+------------+--------+------+---------------------+--------+----------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | count(*) | +--------+------------+--------+------+---------------------+--------+----------+ | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | 1 | | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | 6 | +--------+------------+--------+------+---------------------+--------+----------+ 2 rows in set (0.00 sec) mysql> select * from sentGifts group by whenSent; +--------+------------+--------+------+---------------------+--------+ | sentID | whenSent | fromID | toID | trytryWhen | giftID | +--------+------------+--------+------+---------------------+--------+ | 5 | 2010-03-03 | 11 | 22 | 2010-03-03 00:00:00 | 6 | | 1 | 2010-04-24 | 123 | 456 | 2010-04-24 01:52:20 | 100 | +--------+------------+--------+------+---------------------+--------+ 2 rows in set (0.00 sec) Only 1 row is returned per "group". What does it mean when there is no "Count(*)", etc when using "Group By", and what are it uses? thanks.

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  • How can I search for a string in a .txt file for NSScanner?

    - by pixelbitapps
    I currently have the following code to get a certain piece of code from the UIWebView: NSURL *requestTimetableURL = [NSURL URLWithString:@"http://www.dhsb.org/index.phtml?d=201435"]; NSLog(@"Loaded Timetable"); NSError *error; NSString *page = [NSString stringWithContentsOfURL:requestTimetableURL encoding:NSASCIIStringEncoding error:&error]; [webView loadHTMLString:page baseURL:requestTimetableURL]; NSString* Period1; NSScanner *htmlScanner = [NSScanner scannerWithString:page]; [htmlScanner scanUpToString:@"<P align=center><STRONG><FONT color=#c00000>" intoString:NULL]; [htmlScanner scanString:@"<P align=center><STRONG><FONT color=#c00000>" intoString:NULL]; [htmlScanner scanUpToString:@"</FONT>" intoString:&Period1]; How can I scan a .txt file (which contains the string like above) for the code? E.G. [htmlScanner scanUpToString:teststring intoString:NULL]; Thanks!

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  • Instantiating spring beans in dynamically created classes.

    - by Xetius
    I am dynamically creating classes which contain spring beans, however the beans are not getting instantiated or initialised, leaving them as null. How do I make sure that a dynamically created class creates all of its spring beans properly? This is how I am dynamically creating the class: Class ctransform; try { ctransform = Class.forName(strClassName); Method handleRequestMethod = findHandleRequestMethod(ctransform); if (handleRequestMethod != null) { return (Message<?>) handleRequestMethod.invoke(ctransform.newInstance(), message); } } This leaves all spring bean objects within ctransform (of type strClassName) as null.

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  • Speaking at SQL Saturday #146

    - by Andrew Kelly
      For any of you up in the New England area that are looking for some good and free SQL Server training you may want to check out the SQL Saturday this fall in southern NH. More specifically the event will be held in Nashua NH on October 20th 2012. There is a wonderful cast of speakers including myself (shameless plug ) with a wide range of topics of which I am sure everyone can find a few topics they are interested in.  I hope to see some familiar faces from my old stomping ground and...(read more)

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  • Want to calculate the sum of the count rendered by group by option..

    - by Vijay
    i have a table with the columns such id, tid, companyid, ttype etc.. the id may be same for many companyid but unique within the companyid and tid is always unique and i want to calculate the total no of transactions entered in the table, a single transaction may be inserted in more than one row, for example, id tid companyid ttype 1 1 1 xxx 1 2 1 may be null 2 3 1 yyy 2 4 1 may be null 2 5 1 may be null the above entries should be counted as only 2 transactions .. it may be repeated for many companyids.. so how do i calculate the total no of transactions entered in the table i tried select sum(count(*)) from transaction group by id,companyId; but doesn't work select count(*) from transaction group by id; wont work because the id may be repeated for different companyids.

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  • Drupal 6 devel module dd() function not writing to drupal_debug.txt file

    - by Mike Munroe
    I am running a local development Drupal site on a Windows machine. I am trying to use the dd($data, $label = NULL) function from the devel module to help debug. Using this function, should write debug info to a drupal_debug.txt file in the /tmp folder on the machine where the Drupal site is hosted. On my Windows machine, although I am using this function, the drupal_debug.txt file is not getting created anywhere, leading me to believe I am using the function incorrectly. Here is a snippet of how I am using it, <?php $test = "this is my test"; dd($test, $label = NULL); I am looking for an example of the correct syntax for the dd($data, $label = NULL) function. I have the Devel module enabled.

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