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  • @OneToOne and @JoinColumn, auto delete null entity , doable?

    - by smallufo
    I have two Entities , with the following JPA annotations : @Entity @Table(name = "Owner") public class Owner implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id") private long id; @OneToOne(fetch=FetchType.EAGER , cascade=CascadeType.ALL) @JoinColumn(name="Data_id") private Data Data; } @Entity @Table(name = "Data") public class Data implements Serializable { @Id private long id; } Owner and Data has one-to-one mapping , the owning side is Owner. The problem occurs when I execute : owner.setData(null) ; ownerDao.update(owner) ; The "Owner" table's Data_id becomes null , that's correct. But the "Data" row is not deleted automatically. I have to write another DataDao , and another service layer to wrap the two actions ( ownerDao.update(owner) ; dataDao.delete(data); ) Is it possible to make a data row automatically deleted when the owning Owner set it to null ?

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  • concatenating results from SQL query and NULL columns

    - by Curtis
    I need to concatenate several columns of a table into a single value, then show that value in an asp dropdownlist. The SQL code I'm issuing is as follows: SELECT UserID, CustomerNum, UserName + ' - ' + UserAddress + ',' + UserCity + ' ' + UserState AS UserInfo FROM Users WHERE (CustomerNum = @CustomerNum) ORDER BY UserName I then set 'UserInfo' as the text field in the dropdownlist. This generally works, except occasionally one of the columns in the database is null (for example, UserState). When that happens, the entire concatenation is null, and I get an empty entry in the dropdownlist. Is there something in SQLServer that will allow me to ignore those NULL results, or will I have to code something up in the DataBind event? Thanks

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  • C++ run error: pointer being freed was not allocated

    - by Dale Reves
    I'm learning c++ and am working on a program that keeps giving me a 'pointer being freed was not allocated' error. It's a grocery store program that inputs data from a txt file, then user can enter item# & qty. I've read through similar questions but what's throwing me off is the 'pointer' issue. I would appreciate if someone could take a look and help me out. I'm using Netbeans IDE 7.2 on a Mac. I'll just post the whole piece I have so far. Thx. #include <iostream> #include <fstream> #include <string> #include <vector> using namespace std; class Product { public: // PLU Code int getiPluCode() { return iPluCode; } void setiPluCode( int iTempPluCode) { iPluCode = iTempPluCode; } // Description string getsDescription() { return sDescription; } void setsDescription( string sTempDescription) { sDescription = sTempDescription; } // Price double getdPrice() { return dPrice; } void setdPrice( double dTempPrice) { dPrice = dTempPrice; } // Type..weight or unit int getiType() { return iType; } void setiType( int iTempType) { iType = iTempType; } // Inventory quantity double getdInventory() { return dInventory; } void setdInventory( double dTempInventory) { dInventory = dTempInventory; } private: int iPluCode; string sDescription; double dPrice; int iType; double dInventory; }; int main () { Product paInventory[21]; // Create inventory array Product paPurchase[21]; // Create customer purchase array // Constructor to open inventory input file ifstream InputInventory ("inventory.txt", ios::in); //If ifstream could not open the file if (!InputInventory) { cerr << "File could not be opened" << endl; exit (1); }//end if int x = 0; while (!InputInventory.eof () ) { int iTempPluCode; string sTempDescription; double dTempPrice; int iTempType; double dTempInventory; InputInventory >> iTempPluCode >> sTempDescription >> dTempPrice >> iTempType >> dTempInventory; paInventory[x].setiPluCode(iTempPluCode); paInventory[x].setsDescription(sTempDescription); paInventory[x].setdPrice(dTempPrice); paInventory[x].setiType(iTempType); paInventory[x].setdInventory(dTempInventory); x++; } bool bQuit = false; //CREATE MY TOTAL VARIABLE HERE! int iUserItemCount; do { int iUserPLUCode; double dUserAmount; double dAmountAvailable; int iProductIndex = -1; //CREATE MY SUBTOTAL VARIABLE HERE! while(iProductIndex == -1) { cout<<"Please enter the PLU Code of the product."<< endl; cin>>iUserPLUCode; for(int i = 0; i < 21; i++) { if(iUserPLUCode == paInventory[i].getiPluCode()) { dAmountAvailable = paInventory[i].getdInventory(); iProductIndex = i; } } //PLU code entry validation if(iProductIndex == -1) { cout << "You have entered an invalid PLU Code."; } } cout<<"Enter the quantity to buy.\n"<< "There are "<< dAmountAvailable << "available.\n"; cin>> dUserAmount; while(dUserAmount > dAmountAvailable) { cout<<"That's too many, please try again"; cin>>dUserAmount; } paPurchase[iUserItemCount].setiPluCode(iUserPLUCode);// Array of objects function calls paPurchase[iUserItemCount].setdInventory(dUserAmount); paPurchase[iUserItemCount].setdPrice(paInventory[iProductIndex].getdPrice()); paInventory[iProductIndex].setdInventory( paInventory[iProductIndex].getdInventory() - dUserAmount ); iUserItemCount++; cout <<"Are you done purchasing items? Enter 1 for yes and 0 for no.\n"; cin >> bQuit; //NOTE: Put Amount * quantity for subtotal //NOTE: Put code to update subtotal (total += subtotal) // NOTE: Need to create the output txt file! }while(!bQuit); return 0; }

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  • C Class Instance from Void Pointer using Ctypes

    - by g.d.d.c
    I've got a C DLL that exposes a handful of methods that return void pointers to a Class like so: void *GetLicense() { static AppLicenseImpl ipds_; return (void *) &ipds_; } In C++, after loading the DLL, I'd do this to work with it: typedef void *(* FPGetLicense)(); GetLicense_ = (FPGetLicense)GetAddress("GetLicense"); license_ = (AppLicense *) GetLicense_(); license_->GetApplicationStatus(); // Load data so that other calls don't fail I can't figure out how to parallel that in Python. This gets me the pointer: d = ctypes.cdll.LoadLibrary('license.dll') d.GetLicense.restype = ctypes.c_void_p p = d.GetLicense() # returns ptr loc, something like 8791433660848L But I obviously can't call p.GetApplicationStatus() in Python. Does anyone have a suggestion on how I'd instantiate that Class the rest of the way in Python so that I can call GetApplicationStatus()?

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  • Dangling pointer

    - by viswanathan
    Does this piece of code lead to dangling pointer. My guess is no. class Sample { public: int *ptr; Sample(int i) { ptr = new int(i); } ~Sample() { delete ptr; } void PrintVal() { cout << "The value is " << *ptr; } }; void SomeFunc(Sample x) { cout << "Say i am in someFunc " << endl; } int main() { Sample s1 = 10; SomeFunc(s1); s1.PrintVal(); }

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  • nullable type and a ReSharper warning

    - by Sarah Vessels
    I have the following code: private static LogLevel? _logLevel = null; public static LogLevel LogLevel { get { if (!_logLevel.HasValue) { _logLevel = readLogLevelFromFile(); } return _logLevel.Value; } } private static LogLevel readLogLevelFromFile() { ... } I get a ReSharper warning on the return statement about a possible System.InvalidOperationException and it suggests I check _logLevel to see if it is null first. However, readLogLevelFromFile returns LogLevel, not LogLevel?, so there is no way the return statement could be reached when _logLevel is null. Is this just an oversight by ReSharper, or am I missing something?

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  • IEnumerable not null but calling Count() results in Exception

    - by Draak
    I have code that's working beautifully on my development machine, but when deployed to the server is throwing null reference exception. So, I can't step through the code, but I've pinned down the culprit. But now I am puzzled. Here's the code. The question is below. Dim certs = From p In persons _ Select New Certificate( _ p.Value, _ New CertificateData.Seminar(thisEvent.Seminar.Name, _ thisEvent.StartDate.Value, _ thisEvent.EndDate.Value, _ thisEvent.Venue.City, _ thisEvent.Venue.State, _ New CertificateData.Instructor( _ staffMember.Name, _ staffMember.Titles, _ instrSignatPath))) _ With {.CertificateId = p.Key} lblMessage.Text = CStr(certs Is Nothing) lblMessage.Text = lblMessage.Text + "<br />" + CStr(certs.Count()) In the code above persons is a dictionary of custom class, and certs is of IEnumerable type. Now here's the quandary.. The first line that sets the label returns False, so certs is not null. But the second line throws an null reference exception. How is this possible?

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  • Avoid incompatible pointer warning when dealing with double-indirection

    - by fnawothnig
    Assuming this program: #include <stdio.h> #include <string.h> static void ring_pool_alloc(void **p, size_t n) { static unsigned char pool[256], i = 0; *p = &pool[i]; i += n; } int main(void) { char *str; ring_pool_alloc(&str, 7); strcpy(str, "foobar"); printf("%s\n", str); return 0; } ... is it possible to somehow avoid the GCC warning test.c:12: warning: passing argument 1 of ‘ring_pool_alloc’ from incompatible pointer type test.c:4: note: expected ‘void **’ but argument is of type ‘char **’ ... without casting to (void**) (or simply disabling the compatibility checks)? Because I would very much like to keep compatibility warnings regarding indirection-level...

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  • storing an integer constant other than zero in a pointer variable

    - by benjamin button
    int main() { int *d=0; printf("%d\n",*d); return 0; } this works fine. >cc legal.c > ./a.out 0 if i change the statement int *d=0; to int *d=1; i see the error. cc: "legal.c", line 6: error 1522: Cannot initialize a pointer with an integer constant other than zero. so its obvious that it will allow only zero.i want to know what happens inside the memory when we do this int *d=0 which is making it valid syntax. I am just asking this out of curiosity!

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  • Void pointer values comparing C++

    - by user2962977
    My actual question is it really possible to compare values contained in two void pointers, when you actually know that these values are the same type? For example int. void compVoids(void *firstVal, void *secondVal){ if (firstVal < secondVal){ cout << "This will not make any sense as this will compare addresses, not values" << endl; } } Actually I need to compare two void pointer values, while outside the function it is known that the type is int. I do not want to use comparison of int inside the function. So this will not work for me as well: if (*(int*)firstVal > *(int*)secondVal) Any suggestions? Thank you very much for help!

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  • Converting c pointer types

    - by bobbyb
    I have a c pointer to a structre type called uchar4 which looks like { uchar x; uchar y; uchar z; uchar w; } I also have data passed in as uint8*. I'd like to create a uchar* pointing to the data at the uint8* so I've tried doing this: uint8 *data_in; uchar4 *temp = (uchar4*)data_in; However, the first 8 bytes always seem to be wrong. Is there another way of doing this?

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  • Nested for loop error with !null checking an element that doesn't exist

    - by Programatt
    I am currently using nested for loops in a 2D array of size 4,2. When I run my program, I get index out of bounds Exception on the following line else if (state[i][j+1] != null && state[i][j].getFlash() <= state[i][j].getCycleLength() && state[i][j+1].getCycleLength() == state[i][j].getCycleLength()){ } It says the index out of bounds is 2. I would understand the error if I wasn't checking to see if [i][j+1] wasn't null, but I don't understand the exception with the check? I tried moving around the !null check but the program still fails on this line. Any help would be greatly appreciated. Stack trace: Exception in thread "Timer-0" java.lang.ArrayIndexOutOfBoundsException: 2 at NatComp.data$1.run(data.java:67) at java.util.TimerThread.mainLoop(Timer.java:512) at java.util.TimerThread.run(Timer.java:462)

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  • typeof === "undefined" vs. != null

    - by Thor Thurn
    I often see JavaScript code which checks for undefined parameters etc. this way: if (typeof input !== "undefined") { // do stuff } This seems kind of wasteful, since it involves both a type lookup and a string comparison, not to mention its verbosity. It's needed because 'undefined' could be renamed, though. My question is: How is that code any better than this approach: if (input != null) { // do stuff } As far as I know, you can't redefine null, so it's not going to break unexpectedly. And, because of the type-coercion of the != operator, this checks for both undefined and null... which is often exactly what you want (e.g. for optional function parameters). Yet this form does not seem widespread, and it even causes JSLint to yell at you for using the evil != operator. Why is this considered bad style?

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  • Object pointer value as key into dictionary

    - by Ranking Stackingblocks
    I want to use the object's reference value as a key into a dictionary, as opposed to a copy of value of the object. So, I essentially want to store an object associated with a particular instance of another object in a dictionary and retrieve that value later. Is this possible? Is it completely against the idea of NSDictionary? I can tell that I am probably approaching this the wrong way because the dictionary wants me to implement NSCopying on the object itself, which doesn't really make sense in terms of what I'm doing. I can see that what I should really be doing is wrapping the pointer value, but that seems a little mad. Advice would be appreciated.

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  • (this == null) in C#!

    - by SLaks
    Due to a bug that was fixed in C# 4, the following program prints true. (Try it in LINQPad) void Main() { new Derived(); } class Base { public Base(Func<string> valueMaker) { Console.WriteLine(valueMaker()); } } class Derived : Base { string CheckNull() { return "Am I null? " + (this == null); } public Derived() : base(() => CheckNull()) { } } In VS2008 in Release mode, in throws an InvalidProgramException. (In Debug mode, it works fine) In VS2010 Beta 2, it doesn't compile (I didn't try Beta 1); I learned that the hard way Is there any other way to make this == null in pure C#?

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  • inode_operations , warning: initialization from incompatible pointer type

    - by djTeller
    Hi everyone, I'm trying to compile a simple Kernel program that read and write from a proc file. I'm trying to set permission to that file by overriding the permission fp in inode_operations struct (.permission) static int module_permission(struct inode *inode, int op, struct nameidata *foo) { . . . } static struct inode_operations Inode_Ops_4_Our_Proc_File = { .permission = module_permission, /* check for permissions */ }; Our_Proc_File->proc_iops = &Inode_Ops_4_Our_Proc_File; For some reason, when I compile this i get - warning: initialization from incompatible pointer type on the following line: .permission = module_permission, /* check for permissions */ Any idea how to solve this? Thanks!

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  • When can argv[0] have null ?

    - by andrew-dufresne
    What I have understand about passing arguments to main() from command line is that argc has a minimum value of 1 and argv[0] will always have the program name with its path in it. If arguments are provided at the command line, then argc will have a value greater than one and argv1 to argv[argc-1] will have those arguments. Now a paragraph at this link says that argv[0] will be a string containing the program's name or a null string if that is not available. Now, how and when can argv[0] have null string? I mean program name with its path will always be available so when can it be null? Writer says that "if that is not available" but when and how it is possible that program name will not be available? Thanks for your time and support. Regards

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  • C# Events and Lambdas, alternative to null check?

    - by Eugarps
    Does anybody see any drawbacks? It should be noted that you can't remove anonymous methods from an event delegate list, I'm aware of that (actually that was the conceptual motivation for this). The goal here is an alternative to: if (onFoo != null) onFoo.Invoke(this, null); And the code: public delegate void FooDelegate(object sender, EventArgs e); public class EventTest { public EventTest() { onFoo += (p,q) => { }; } public FireFoo() { onFoo.Invoke(this, null); } public event FooDelegate onFoo; }

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  • JSP doPost getAtribute null value

    - by newbie123
    I want to pass value to servlet but I keep get null value. <jsp:useBean id="Helper" class="model.Registration" scope="request"/> <form action="/Project/Registration" method="post" enctype="multipart/form-data"> <input type="text" size="20" name="name" value="<%=Helper.getName()%>"> <input type="submit"> </form> protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Registrationh2 = (Registration) request.getAttribute("Helper"); if(h2!=null){ System. out.println(h2.getName()); } else System. out.println("NULL"); } Is there anything wrong with my code?

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  • pointer delegate in STL set.

    - by ananth
    hi. Im kinda stuck with using a set with a pointer delegate. my code is as follows: void Graph::addNodes (NodeSet& nodes) { for (NodeSet::iterator pos = nodes.begin(); pos != nodes.end(); ++pos) { addNode(*pos); } } Here NodeSet is defined as: typedef std::set NodeSet; The above piece of code works perfectly on my windows machine, but when i run the same piece of code on a MAC, it gives me the following error: no matching function for call to 'Graph::addNode(const boost::shared_ptr&)' FYI, Node_ptr is of type: typedef boost::shared_ptr Node_ptr; can somebody plz tell me why this is happening?

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  • C Structure Pointer Problem

    - by Halo
    I have this struct; #define BUFSIZE 10 struct shared_data { pthread_mutex_t th_mutex_queue; int count; int data_buffer_allocation[BUFSIZE]; int data_buffers[BUFSIZE][100]; }; and I want to allocate one of the data_buffers for a process, for that purpose I execute the following function; int allocate_data_buffer(int pid) { int i; for (i = 0; i < BUFSIZE; i++) { if (sdata_ptr->data_buffer_allocation[i] == NULL) { sdata_ptr->data_buffer_allocation[i] = pid; return i; } } return -1; } but the compiler warns me that I'm comparing pointer to a value. When I put a & in front of sdata_ptr it calms down but I'm not sure if it will work. Isn't what I wrote above supposed to be true?

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  • Function template accepting nothing less than a bidirectional iterator or a pointer

    - by san
    I need a function template that accepts two iterators that could be pointers. If the two arguments are random_access iterators I want the return type to be an object of std::iterator<random_access_iterator_tag, ...> type else a std::iterator<bidirectional_iterator_tag, ...> type. I also want the code to refuse compilation if the arguments are neither a bidirectional iterator, nor a pointer. I cannot have dependency on third party libraries e.g. Boost Could you help me with the signature of this function so that it accepts bidirectional iterators as well as pointers, but not say input_iterator, output_iterator, forward_iterators. One partial solution I can think of is the following template<class T> T foo( T iter1, T iter2) { const T tmp1 = reverse_iterator<T>(iter1); const T tmp2 = reverse_iterator<T>(iter2); // do something } The idea is that if it is not bidirectional the compiler will not let me construct a reverse_iterator from it.

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  • routing paramenter returns null when only supplying first paramenter in MVC

    - by Ray ForRespect
    My issue is that I customer Map Route in MVC which takes three parameters. When I supply all three or just two, the parameters are passed from the URL to my controller. However, when I only supply the first parameter, it is not passed and returns null. Not sure what causes this behavior. Route: routes.MapRoute( name: "Details", // Route name url: "{controller}/{action}/{param1}/{param2}/{param3}", // URL with parameters defaults: new { controller = "Details", action = "Index", param1 = UrlParameter.Optional, param2 = UrlParameter.Optional, param3 = UrlParameter.Optional } // Parameter defaults ); Controller: public ActionResult Map(string param1, string param2, string param3) { StoreMap makeMap = new StoreMap(); var storemap = makeMap.makeStoreMap(param1, param2, param3); var model = storemap; return View(model); } string param1 returns null when I navigate to: /StoreMap/Map/PARAM1NAME but it doesn't return null when I navigate to: /StoreMap/Map/PARAM1NAME/PARAM2NAME

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  • Cannot output json from MySQL - getting null value

    - by sky
    I'm using following code but cannot return data from MySQL. This is the output: <script type="text/javascript"> var somethings= [null,null,null]; </script> It does have three post, but I couldn't get the title(message) output. EDIT: this is the code I'm using: <?php $session = mysql_connect('localhost','name','pass'); mysql_select_db('dbname', $session); $result= mysql_query('SELECT * FROM posts', $session); $somethings= array(); while ($row= mysql_fetch_assoc($result)) { $somethings[]= $row['something']; } ?> <script type="text/javascript"> var somethings= <?php echo json_encode($somethings); ?>; </script>

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  • how do you find the exact variable of a null pointer exception

    - by OVERTONE
    I've been at this one for a bit now. I've got a null pointer exception so im guessing somethings not been initialized. AdminMessages.inbox1.setText(messageRsetArray[0]); thats my code where its targetting. but i cant find what inside it hasnt been initiazed. AdminMessages is a class which contains a JTextField called inbox1, messageRsetArray is an array which has taken variables from an array. also inbox1 is static. i coulndt get the getters and setter to work. i know its bad practice though.

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