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  • php oop and mysql

    - by gloris
    I need to get data, to check and send to db. Programming with PHP OOP. Could you tell me if my class structure is good and how dislpay all data?. Thanks <?php class Database{ private $DBhost = 'localhost'; private $DBuser = 'root'; private $DBpass = 'root'; private $DBname = 'blog'; public function connect(){ //Connect to mysql db } public function select($rows){ //select data from db } public function insert($rows){ //Insert data to db } public function delete($rows){ //Delete data from db } } class CheckData{ public $number1; public $number2; public function __construct(){ $this->number1 = $_POST['number1']; $this->number2 = $_POST['number2']; } function ISempty(){ if(!empty($this->$number1)){ echo "Not Empty"; $data = new Database(); $data->insert($this->$number1); } else{ echo "Empty1"; } if(!empty($this->$number2)){ echo "Not Empty"; $data = new Database(); $data->insert($this->$number2); } else{ echo "Empty2"; } } } class DisplayData{ //How print all data? function DisplayNumber(){ $data = new Database(); $data->select(); } } $check = new CheckData(); $check->ISempty(); $display = new DisplayData() $display->DisplayNumber(); ?>

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  • How to stop the submission of the form using JQUERY?

    - by Param-Ganak
    Hello frineds! I have a form which have many check boxes in it. User will check one or many checkboxes and click on Delete button which is actually submit button then the respective records for selected check boxes are get deleted. Required operation steps are as follows:- When user selects one or more checkboxes and clicks the submit button then a JQUERY code is get executed in which It should checks that if any check box is selected; if not; then is displays alert message and do not submit the form. If it founds that one or more checkboxes are selected it should ask user for his/her confirmation using confirm alert box about the confirmation of deletion. If user press YES button on confirm box then it should submit the form using javascript submit statement. If user pressed the NO button then it should unchecks the checked selected checkboxes and should not submit the form. This is the JQUERY code I had written. $(document).ready(function (){ $("#id_delete").click(function(){ var temp=$("#id_frm input:checkbox:checked"); var len=temp.length; if(len==0) { alert("Please select the order."); } else { if(confirm("Are you sure to delete the selected orders.")) { $("#id_frm").submit(); } else { temp.checked=false; } } }); }); Problems: This code is not working properly. Here 1. It submits form when there is no check box is selected. 2. It submits the form when user press NO button on confirmation dialog box. Please guide me friends in this problem.

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  • Copy constructor demo (crashing...)

    - by AKN
    Here is the program... class CopyCon { public: char *name; CopyCon() { name = new char; } CopyCon(const CopyCon &objCopyCon) { name = new char; _tcscpy(name,objCopyCon.name); } ~CopyCon() { if( name != NULL ) { delete name; name = NULL; } } }; int main() { CopyCon objCopyCon1; objCopyCon1.name = "Hai"; CopyCon objCopyCon2(objCopyCon1); objCopyCon1.name = "Hello"; cout<<objCopyCon2.name<<endl; return 0; } Once the code execution completes, when the destructor called, it crashes on 'delete' saying... Debug Error! Program: ... HEAP CORRUPTION DETECTED: after Normal block (#124) at 0x00366990. CRT detected that the application wrote to memory after end of heap buffer. (Press Retry to debug the application) Don't we have to clear the heap memory in destructor. What's wrong with this program? Pls someone help! Copy constructor works perfectly as intended. But still... !?

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  • Is it Possible to Use Constraints on Hierarchical Data in a Self-Referential Table?

    - by pbarney
    Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to cascade on update and prevent deletion of a record if it has any "children." So I used the following: CREATE TABLE `test`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

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  • NHibernate many-to-many relationship does not update join-table

    - by Davide Vosti
    I'm having trouble saving a many-to-many relationship with nhibernate. I searched and looked at almost every same question in SO and google but nothing works. The single classes are update correctly but nothing is inserted in the join-table. I have 2 classes: Event and Category. The mapping is this: Event: <bag name="Categories" access="field.camelcase-underscore" table="EventCategories" inverse="true" cascade="all-delete-orphan" lazy="true"> <key column="Event"/> <many-to-many class="Category" column="Category"/> </bag> Category: <bag name="Events" table="EventCategories" access="field.camelcase-underscore" cascade="all-delete-orphan" lazy="true" > <key column="Category"/> <many-to-many class="Event" column="Event"/> </bag> I tried to swap every parameter in both mappings but nothing works... Do you know what I'm doing wrong or have a right mapping for this case? Thank you very much!

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  • Why does the WCF 3.5 REST Starter Kit do this?

    - by Brandon
    I am setting up a REST endpoint that looks like the following: [WebInvoke(Method = "POST", UriTemplate = "?format=json", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json)] and [WebInvoke(Method = "DELETE", UriTemplate = "?token={token}&format=json", ResponseFormat = WebMessageFormat.Json)] The above throws the following error: UriTemplateTable does not support '?format=json' and '?token={token}&format=json' since they are not equivalent, but cannot be disambiguated because they have equivalent paths and the same common literal values for the query string. See the documentation for UriTemplateTable for more detail. I am not an expert at WCF, but I would imagine that it should map first by the HTTP Method and then by the URI Template. It appears to be backwards. If both of my URI templates are: ?token={token}&format=json This works because they are equivalent and it then appears to look at the HTTP Method where one is POST and the other is DELETE. Is REST supposed to work this way? Why are the URI Template Tables not being sorted first by HTTP Method and then by URI Template? This can cause some serious frustrations when 1 HTTP Method requires a parameter and another does not, or if I want to do optional parameters (e.g. if the 'format' parameter is not passed, default to XML).

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  • Help with create action in a different show page

    - by Andrew
    Hi, I'm a Rails newbie and want to do something but keep messing something up. I'd love some help. I have a simple app that has three tables. Users, Robots, and Recipients. Robots belong_to users and Recipients belong_to robots. On the robot show page, I want to be able to create recipients for that robot right within the robot show page. I have the following code in the robot show page which lists current recipients: <table> <% @robot.recipients.each do |recipient| %> <tr> <td><b><%=h recipient.chat_screen_name %></b> via <%=h recipient.protocol_name</td> <td><%= link_to 'Edit', edit_recipient_path(recipient) %>&nbsp;</td> <td><%= link_to 'Delete', recipient, :confirm => 'Are you sure?', :method => :delete %></td> </tr> <% end %> </table> What I'd like to do is have an empty field in which the user can add a new recipient, and have tried the following: I added this to the Robots Show view: <% form_for(@robot.recipient) do |f| %> Enter the screen name<br> <%= f.text_field :chat_screen_name %> <p> <%= f.submit 'Update' %> </p> <% end %> and then this to the Robot controller in the show action: @recipient = Recipient.new @recipients = Recipient.all Alas, I'm still getting a NoMethod error that says: "undefined method `recipient' for #" I'm not sure what I'm missing. Any help would be greatly appreciated. Thank you.

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  • Double null-terminated string

    - by wengseng
    I need to format a string to be double null-terminated string in order to use SHFileOperation. Interesting part is i found one of the following working, but not both: // Example 1 CString szDir(_T("D:\\Test")); szDir = szDir + _T('\0') + _T('\0'); // Example 2 CString szDir(_T("D:\\Test")); szDir = szDir + _T("\0\0"); //Delete folder SHFILEOPSTRUCT fileop; fileop.hwnd = NULL; // no status display fileop.wFunc = FO_DELETE; // delete operation fileop.pFrom = szDir; // source file name as double null terminated string fileop.pTo = NULL; // no destination needed fileop.fFlags = FOF_NOCONFIRMATION|FOF_SILENT; // do not prompt the user fileop.fAnyOperationsAborted = FALSE; fileop.lpszProgressTitle = NULL; fileop.hNameMappings = NULL; int ret = SHFileOperation(&fileop); Does anyone has idea on this? Is there other way to append double-terminated string?

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  • Password security; Is this safe?

    - by Camran
    I asked a question yesterday about password safety... I am new at security... I am using a mysql db, and need to store users passwords there. I have been told in answers that hashing and THEN saving the HASHED value of the password is the correct way of doing this. So basically I want to verify with you guys this is correct now. It is a classifieds website, and for each classified the user puts, he has to enter a password so that he/she can remove the classified using that password later on (when product is sold for example). In a file called "put_ad.php" I use the $_POST method to fetch the pass from a form. Then I hash it and put it into a mysql table. Then whenever the users wants to delete the ad, I check the entered password by hashing it and comparing the hashed value of the entered passw against the hashed value in the mysql db, right? BUT, what if I as an admin want to delete a classified, is there a method to "Unhash" the password easily? sha1 is used currently btw. some code is very much appreciated. Thanks

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  • Cakephp cache only caching one file per action

    - by Jamesz
    Hi, I have a songs controller. Within the songs controller i have a 'view' action which get's passed an id, eg /songs/view/1 /songs/view/5 /songs/view/500 When a user visits /songs/view/1, the file is cached correctly and saved as 'songs_view_1.php' Now for the problem, when a user hit's a different song, eg /songs/view/2, the 'songs_view_1.php' is deleted and '/songs/view/2.php' is in it's place. The cahced files will stay there for a day if I don't visit a different url, and visiting a different action will not affect any other action's cached file. I've tried replacing my 'cake' folder (from 1.2 to 1.2.6), but that didn't do anything. I get no error messages at all and nothing in the logs. Here's my code, I've tried umpteen variations all ending up with the same problem. var $helpers = array('Cache'); var $cacheAction = array( 'view/' => '+1 day' ); Any ideas? EDIT: After some more testing, this code var $cacheAction = array( 'view/1' => "1 day", 'view/2' => "1 day" ); will cache 'view/1' or 'view/2', but delete the previous page as before. If I visit '/view/3' it will delete the cached page from before... sigh EDIT: Having the same issue on another server with same code...

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  • Can this code cause a memory leak (Arduino)

    - by tbraun89
    I have a arduino project and I created this struct: struct Project { boolean status; String name; struct Project* nextProject; }; In my application I parse some data and create Project objects. To have them in a list there is a pointer to the nextProject in each Project object expect the last. This is the code where I add new projects: void RssParser::addProject(boolean tempProjectStatus, String tempData) { if (!startProject) { startProject = true; firstProject.status = tempProjectStatus; firstProject.name = tempData; firstProject.nextProject = NULL; ptrToLastProject = &firstProject; } else { ptrToLastProject->nextProject = new Project(); ptrToLastProject->nextProject->status = tempProjectStatus; ptrToLastProject->nextProject->name = tempData; ptrToLastProject->nextProject->nextProject = NULL; ptrToLastProject = ptrToLastProject->nextProject; } } firstProject is an private instance variable and defined in the header file like this: Project firstProject; So if there actually no project was added, I use firstProject, to add a new one, if firstProject is set I use the nextProject pointer. Also I have a reset() method that deletes the pointer to the projects: void RssParser::reset() { delete ptrToLastProject; delete firstProject.nextProject; startProject = false; } After each parsing run I call reset() the problem is that the memory used is not released. If I comment out the addProject method there are no issues with my memory. Someone can tell me what could cause the memory leak?

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  • Calling NSFetchedResultsController & CoreData experts

    - by JK
    I am having a few nagging issues with NSFetchedResultsController and CoreData, any of which I would be very grateful to get help on. Issue 1 - Updates: I update my store on a background thread which results in certain rows being delete, inserted or updated. The changes are merged into the context on the main thread using the "mergeChangesFromContextDidSaveNotification:" method. Inserts and deletes are updated properly, but updates are not (e.g. the cell label is not updated with the change) although I have confirmed the updates to come through the contextDidSaveNotifcation, exactly like the inserts and deleted. My current workaround is to temporarily change the staleness interval of the context to 0, but this does not seem like the ideal solution. Issue 2 - Deleting objects: My fetch batch size is 20. If an object is deleted by the background thread which is in the first 20 rows, everything works fine. But if the object is after the first 20 rows and the table is scrolled down, a "CoreData could not fulfill a fault" error is raised. I have tried resaving the context and reperforming the frc fetch - all to no avail. Note: In this scenario, the frc delegate method "didChangeObject...." is not called for the delete - I assume this is because the object in question had not been faulted at that time (as it is was outside the initial fetch range). But for some reason, the context still thinks the object is around, although is has been deleted from the store. Issue 3 - Deleting sections : When the deletion of a row leads to the deletion of a section, I have gotten the "invalid number of rows in section???" error. I have worked around this by removing the "reloadSection" line from the NSFetchedResultsChangeMove: section and replacing it with "[tableView insertRowsAtIndexPaths...." This seems to work, but once again, I am not sure if this is the best solution. Any help would be greatly appreciated. Thank you!

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  • Mapping individual buttons on ASP.NET MVC View to controller actions

    - by skb
    I have an application where I need the user to be able to update or delete rows of data from the database. The rows are displayed to the user using a foreach loop in the .aspx file of my view. Each row will have two text fields (txtName, txtDesc), an update button, and a delete button. What I'm not sure of, is how do I have the update button send the message to the controller for which row to update? I can see a couple way of doing this: Put each row within it's own form tag, then when the update button is clicked, it will submit the values for that row only (there will also be a hidden field with the rowId) and the controller class would take all the post values as parameters to the Update method on the controller. Somehow, have the button be scripted in a way to send back only the values for that row with a POST to the controller. Is there a way of doing this? One thing I am concerned about is if each row has different names for it's controls assigned by ASP.NET (txtName1, txtDesc1, txtName2, txtDesc2), then how will their values get mapped to the correct parameters of the Controller method?

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  • How much does an InnoDB table benefit from having fixed-length rows?

    - by Philip Eve
    I know that dependent on the database storage engine in use, a performance benefit can be found if all of the rows in the table can be guaranteed to be the same length (by avoiding nullable columns and not using any VARCHAR, TEXT or BLOB columns). I'm not clear on how far this applies to InnoDB, with its funny table arrangements. Let's give an example: I have the following table CREATE TABLE `PlayerGameRcd` ( `User` SMALLINT UNSIGNED NOT NULL, `Game` MEDIUMINT UNSIGNED NOT NULL, `GameResult` ENUM('Quit', 'Kicked by Vote', 'Kicked by Admin', 'Kicked by System', 'Finished 5th', 'Finished 4th', 'Finished 3rd', 'Finished 2nd', 'Finished 1st', 'Game Aborted', 'Playing', 'Hide' ) NOT NULL DEFAULT 'Playing', `Inherited` TINYINT NOT NULL, `GameCounts` TINYINT NOT NULL, `Colour` TINYINT UNSIGNED NOT NULL, `Score` SMALLINT UNSIGNED NOT NULL DEFAULT 0, `NumLongTurns` TINYINT UNSIGNED NOT NULL DEFAULT 0, `Notes` MEDIUMTEXT, `CurrentOccupant` TINYINT UNSIGNED NOT NULL DEFAULT 0, PRIMARY KEY (`Game`, `User`), UNIQUE KEY `PGR_multi_uk` (`Game`, `CurrentOccupant`, `Colour`), INDEX `Stats_ind_PGR` (`GameCounts`, `GameResult`, `Score`, `User`), INDEX `GameList_ind_PGR` (`User`, `CurrentOccupant`, `Game`, `Colour`), CONSTRAINT `Constr_PlayerGameRcd_User_fk` FOREIGN KEY `User_fk` (`User`) REFERENCES `User` (`UserID`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `Constr_PlayerGameRcd_Game_fk` FOREIGN KEY `Game_fk` (`Game`) REFERENCES `Game` (`GameID`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=INNODB CHARACTER SET utf8 COLLATE utf8_general_ci The only column that is nullable is Notes, which is MEDIUMTEXT. This table presently has 33097 rows (which I appreciate is small as yet). Of these rows, only 61 have values in Notes. How much of an improvement might I see from, say, adding a new table to store the Notes column in and performing LEFT JOINs when necessary?

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  • How can I efficiently manipulate 500k records in SQL Server 2005?

    - by cdeszaq
    I am getting a large text file of updated information from a customer that contains updates for 500,000 users. However, as I am processing this file, I often am running into SQL Server timeout errors. Here's the process I follow in my VB application that processes the data (in general): Delete all records from temporary table (to remove last month's data) (eg. DELETE * FROM tempTable) Rip text file into the temp table Fill in extra information into the temp table, such as their organization_id, their user_id, group_code, etc. Update the data in the real tables based on the data computed in the temp table The problem is that I often run commands like UPDATE tempTable SET user_id = (SELECT user_id FROM myUsers WHERE external_id = tempTable.external_id) and these commands frequently time out. I have tried bumping the timeouts up to as far as 10 minutes, but they still fail. Now, I realize that 500k rows is no small number of rows to manipulate, but I would think that a database purported to be able to handle millions and millions of rows should be able to cope with 500k pretty easily. Am I doing something wrong with how I am going about processing this data? Please help. Any and all suggestions welcome.

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  • Short file names versus long file names in Windows

    - by normski
    I have some code which gets the short name from a file path, using GetShortNameW(), and then later retrieves the long name view GetLongNameA(). The original file is of the form "C:/ProgramData/My Folder/File.ext" However, following conversion to short, then back to long, the filename becomes "C:/Program Files/My Folder/Filename.ext". The short name is of the form "C:/PROGRA~2/MY_FOL~1/FIL~1.EXT" The short name is being incorrectly resolved. The code compiles using VS 2005 on Windows 7 (I cannot upgrade the project to VS2008) Does anybody have any idea why this might be happening? DWORD pathLengthNeeded = ::GetShortPathNameW(aRef->GetFilePath().c_str(), NULL, 0); if(pathLengthNeeded != 0) { WCHAR* shortPath = new WCHAR[pathLengthNeeded]; DWORD newPathNameLength = ::GetShortPathNameW(aRef->GetFilePath().c_str(), shortPath, pathLengthNeeded); if(newPathNameLength != 0) { UI_STRING unicodePath(shortPath); std::string asciiPath = StringFromUserString(unicodePath); pathLengthNeeded = ::GetLongPathNameA(asciiPath.c_str(),NULL, 0); if(pathLengthNeeded != 0) {// convert it back to a long path if possible. For goodness sake can't we use Unicode throughout?F char* longPath = new char[pathLengthNeeded]; DWORD newPathNameLength = ::GetLongPathNameA(asciiPath.c_str(), longPath, pathLengthNeeded); if(newPathNameLength != 0) { std::string longPathString(longPath, newPathNameLength); asciiPath = longPathString; } delete [] longPath; } SetFullPathName(asciiPath); } delete [] shortPath; }

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  • SQL Duplicates Issue

    - by jeff
    I have two tables : Product and ProductRateDetail. The parent table is Product. I have duplicate records in the product table which need to be unique. There are entries in the ProductRateDetail table which correspond to duplicate records in the product table. Somehow I need to update the ProductRateDetail table to match the original (older) ID from the Product table and then remove the duplicates from the product table. I would do this manually but there are 100's of records. I.e. something like UPDATE tbl_productRateDetail SET productID = (originalID from tbl_product) then something like DELETE from tbl_product WHERE duplicate ID and only delete the recently added ID data example: (sorry can't work out this formatting thing) select * from dbo.Product where ProductCode = '10003' tbl_product ProductID ProductTypeID ProductDescription ProductCode ProductSize 365 1 BEND DOUBLE FLANGED 10003 80mmX90deg 1354 1 BEND DOUBLE FLANGED 10003 80mmX90deg SELECT * FROM [MSTS2].[dbo].[ProductRateDetail] WHERE ProductID in (365,1354) tbl_productratedetail ProductRateDetailID ProductRateID ProductID UnitRate 365 1 365 16.87 1032 5 365 16.87 2187 10 365 16.87 2689 11 365 16.87 3191 12 365 16.87 7354 21 1354 21.30 7917 22 1354 21.30 8480 23 1354 21.30 9328 25 1354 21.30 9890 26 1354 21.30 10452 27 1354 21.30 Please help!

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  • Why the compiler is not compiling a line in C++ Builder?

    - by MLB
    Hi boys: I was programming an application in C++ Builder 6, and I had encountered this rare problem: void RotateDice() { Graphics::TBitmap *MYbitmap = new Graphics::TBitmap(); Randomize(); int rn = random(6) + 1; switch (rn) { case 1: { //... break; } //... Some cases... } ShowDice(); //it's a function to show the dice delete MYbitmap; //the compiler don't get it!!!! } In the line "ShowDice()", the compiler jumps to the final of the RotateDice() method, it doesn't "see" the line "delete MYbitmap". When I compile the program, every compiled line shows a little blue point in its left side, but that line don't show the blue point... it's like the compiler don't "see" the line of code. What's happening with that???? Note: Some days ago, I was writing a program in Delphi and I was advice of that problematic issue. Some like that happened to me in Delphi 7... So, waht the problem with that? I am so sorry about my English. I am from Cuba.

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  • Compile C++ in Visual Studio

    - by Kasun
    Hi All.. I use this method to compile C++ file in VS. But even i provide the correct file it returns false. Can any one help me... This is class called CL class CL { private const string clexe = @"cl.exe"; private const string exe = "Test.exe", file = "test.cpp"; private string args; public CL(String[] args) { this.args = String.Join(" ", args); this.args += (args.Length > 0 ? " " : "") + "/Fe" + exe + " " + file; } public Boolean Compile(String content, ref string errors) { if (File.Exists(exe)) File.Delete(exe); if (File.Exists(file)) File.Delete(file); File.WriteAllText(file, content); Process proc = new Process(); proc.StartInfo.UseShellExecute = false; proc.StartInfo.RedirectStandardOutput = true; proc.StartInfo.RedirectStandardError = true; proc.StartInfo.FileName = clexe; proc.StartInfo.Arguments = this.args; proc.StartInfo.CreateNoWindow = true; proc.Start(); //errors += proc.StandardError.ReadToEnd(); errors += proc.StandardOutput.ReadToEnd(); proc.WaitForExit(); bool success = File.Exists(exe); return success; } } This is my button click event private void button1_Click(object sender, EventArgs e) { string content = "#include <stdio.h>\nmain(){\nprintf(\"Hello world\");\n}\n"; string errors = ""; CL k = new CL(new string[] { }); if (k.Compile(content, ref errors)) Console.WriteLine("Success!"); else MessageBox.Show("Errors are : ", errors); }

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  • C++ Dynamic Allocation Mismatch: Is this problematic?

    - by acanaday
    I have been assigned to work on some legacy C++ code in MFC. One of the things I am finding all over the place are allocations like the following: struct Point { float x,y,z; }; ... void someFunc( void ) { int numPoints = ...; Point* pArray = (Point*)new BYTE[ numPoints * sizeof(Point) ]; ... //do some stuff with points ... delete [] pArray; } I realize that this code is atrociously wrong on so many levels (C-style cast, using new like malloc, confusing, etc). I also realize that if Point had defined a constructor it would not be called and weird things would happen at delete [] if a destructor had been defined. Question: I am in the process of fixing these occurrences wherever they appear as a matter of course. However, I have never seen anything like this before and it has got me wondering. Does this code have the potential to cause memory leaks/corruption as it stands currently (no constructor/destructor, but with pointer type mismatch) or is it safe as long as the array just contains structs/primitive types?

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  • mailing system DB structure, need help

    - by Anna
    i have a system there user(sender) can write a note to friends(receivers), number of receivers=0. Text of the message is saved in DB and visible to sender and all receivers then they login to system. Sender can add more receivers at any time. More over any of receivers can edit the message and even remove it from DB. For this system i created 3 tables, shortly: users(userID, username, password) messages(messageID, text) list(id, senderID, receiverID, messageID) in table "list" each row corresponds to pair sender-receiver, like sender_x_ID -- receiver_1_ID -- message_1_ID sender_x_ID -- receiver_2_ID -- message_1_ID sender_x_ID -- receiver_3_ID -- message_1_ID Now the problem is: 1. if user deletes the message from table "messages" how to automatically delete all rows from table "list" which correspond to deleted message. Do i have to include some foreign keys? More important: 2. if sender has let say 3 receivers for his message1 (username1, username2 and username3) and at certain moment decides to add username4 and username5 and at the same time exclude username1 from the list of receivers. PHP code will get the new list of receivers (username2, username3, username4, username5) That means insert to table "list" sender_x_ID -- receiver_4_ID -- message_1_ID sender_x_ID -- receiver_5_ID -- message_1_ID and also delete from table "list" the row corresponding to user1 (which is not in the list or receivers any more) sender_x_ID -- receiver_1_ID -- message_1_ID which sql query to send from PHP to make it in an easy and intelligent way? Please help! Examples of sql queries would be perfect!

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  • pass a pointer of a class

    - by small_potato
    Say I have Class1 and Class2 and I want a shallow copy constructor for Class1. Class1 has a member variable, which is a pointer pointing to a Class2 instance. Also I have to be able to change the Class2 ptr is pointing at. in header file: class Class1 { Class2* ptr; ... } in source file: Class1::Class1() { ptr = new Class2(); } ...... Class2* Class1::Exchange(Class2* newClass2) { Class2* temp; ptr = newClass2; return temp; } ...... Now say Class1 original; Class1 shallowCopy(original); Class2* newClass2 = new Class2(); Class2* oldClass2; oldClass2 = orignal.Exchange(newClass2); delete oldClass2; now I want is associate original.ptr with shallowCopy.ptr, when I implement the shallow copy constructor, how do I make sure these two pointer always point at the same Class2? I mean in the class above, the oldClass2 is deleted, so ptr of shallowCopy is pointing at nothing. If I don't delete oldClass2, ptrs of original and shallowCopy are pointing at different Class2 instance.

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  • When destroying one record, another one gets destroyed

    - by normalocity
    Products (like an iPod Classic) :has_many = :listings, :dependent = :destroy Listings (like "My name is Joe, and I have an iPod for sale) :belongs_to = :product So, if I delete a given Product, all the listings that point to it get deleted. That makes sense, and is by design. However, I am writing a "merge" function, where you merge two Products into one, and combine their Listings. So, let's say my two products are "iPod Color" and "iPod Classic", and I want to merge the two. What I want to do is say, "iPod Color, merge into iPod Classic", and result should be that: All the iPod Color Listings are re-pointed to the iPod Classic product After the product_id change, the Listing(s) are saved I then delete the "iPod Color" product Well, that should all work fine, without deleting any Listings. However, I've got this controller, and for whatever reason when I destroy the "iPod Color" Product, even after confirming that the Listings have been moved to "iPod Classic" and saved to the database, the Listings that were previously pointed to "iPod Color" get destroyed as well, and I can't figure out why. It's as if they are retaining some kind of link to the destroyed product, and therefore begin destroyed themselves. What painfully obvious thing am I missing? def merge merging_from = Product.find(params[:id]) merging_to = Product.find_by_model(params[:merging_to]) unless merging_to.nil? unless merging_from.nil? unless merging_from == merging_to # you don't want to merge something with itself merging_from.listings.each do |l| l.product = merging_to l.save end # through some debugging, I've confirmed that my missing Listings are disappearing as a result of the following destroy call merging_from.destroy end end end

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  • Isn't an Iterator in c++ a kind of a pointer?

    - by Bilthon
    Ok this time I decided to make a list using the STL. I need to create a dedicated TCP socket for each client. So everytime I've got a connection, I instantiate a socket and add a pointer to it on a list. list<MyTcp*> SocketList; //This is the list of pointers to sockets list<MyTcp*>::iterator it; //An iterator to the list of pointers to TCP sockets. Putting a new pointer to a socket was easy, but now every time the connection ends I should disconnect the socket and delete the pointer so I don't get a huge memory leak, right? well.. I thought I was doing ok by setting this: it=SocketList.begin(); while( it != SocketList.end() ){ if((*it)->getClientId() == id){ pSocket = it; // <-------------- compiler complains at this line SocketList.remove(pSocket); pSocket->Disconnect(); delete pSocket; break; } } But the compiler is saying this: error: invalid cast from type ‘std::_List_iterator<MyTcp*>’ to type ‘MyTcp*’ Can someone help me here? i thought I was doing things right, isn't an iterator at any given time just pointing to one of the elements of the set? how can I fix it?

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  • Dependency injection in C++

    - by Yorgos Pagles
    This is also a question that I asked in a comment in one of Miško Hevery's google talks that was dealing with dependency injection but it got buried in the comments. I wonder how can the factory / builder step of wiring the dependencies together can work in C++. I.e. we have a class A that depends on B. The builder will allocate B in the heap, pass a pointer to B in A's constructor while also allocating in the heap and return a pointer to A. Who cleans up afterwards? Is it good to let the builder clean up after it's done? It seems to be the correct method since in the talk it says that the builder should setup objects that are expected to have the same lifetime or at least the dependencies have longer lifetime (I also have a question on that). What I mean in code: class builder { public: builder() : m_ClassA(NULL),m_ClassB(NULL) { } ~builder() { if (m_ClassB) { delete m_ClassB; } if (m_ClassA) { delete m_ClassA; } } ClassA *build() { m_ClassB = new class B; m_ClassA = new class A(m_ClassB); return m_ClassA; } }; Now if there is a dependency that is expected to last longer than the lifetime of the object we are injecting it into (say ClassC is that dependency) I understand that we should change the build method to something like: ClassA *builder::build(ClassC *classC) { m_ClassB = new class B; m_ClassA = new class A(m_ClassB, classC); return m_ClassA; } What is your preferred approach?

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