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  • DNS Pointer to old server name

    - by TechKnow Dude
    We have a SBS2003 server that was migrated to a new hardware platform, the computer name has changed but the domain is the same. The desktop's are trying to do offline files to the old server name. There is a nslookup entry for the old server name and a DNS entry for the old server. How do we safely remove the old DNS entry without breaking the computer offline folder storage locally. Can we change the pointing location on the offline file storage to point to the new server name.

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  • Image annotation with Inkscape, Pointer and explanation for objects in picture

    - by None
    I need straight paths with end markers for associating text to parts of the image. For better readability, it needs to be high-contrast, i.e. a white line with black outline. Stroke to path will create a group of a box and a circle from the line with end marker. This makes placement of the markers more difficult, as with the node tool it is just a matter of dragging the end nodes of a line segment. I will try to place the markers as line for now and only finally converting them to an outline.

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  • Converting a pointer for a base class into an inherited class

    - by Shawn B
    Hey, I'm working on a small roguelike game, and for any object/"thing" that is not a part of the map is based off an XEntity class. There are several classes that depend on it, such as XPlayer, XItem, and XMonster. My problem is, that I want to convert a pointer from XEntity to XItem when I know that an object is in item. The sample code I am using to pick up an item is this, it is when a different entity picks up an item it is standing over. void XEntity::PickupItem() { XEntity *Ent = MapList; // Start of a linked list while(true) { if(Ent == NULL) { break; } if(Ent->Flags & ENT_ITEM) { Ent->RemoveEntity(); // Unlink from the map's linked list XItem *Item = Ent // Problem is here, type-safety // Code to link into inventory is here break; } Ent = Ent->MapList; } } My first thought was to create a method in XEntity that returns itself as an XItem pointer, but it creates circular dependencies that are unresolvable. I'm pretty stumped about this one. Any help is greatly appreciated.

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  • what exactly is the danger of an uninitialized pointer in C

    - by akh2103
    I am trying get a handle on C as I work my way thru Jim Trevor's "Cyclone: A safe dialect of C" for a PL class. Trevor and his co-authors are trying to make a safe version of C, so they eliminate uninitialized pointers in their language. Googling around a bit on uninitialized pointers, it seems like un-initialized pointers point to random locations in memory. It seems like this alone makes them unsafe. If you reference an un-itilialized pointer, you jump to an unsafe part of memory. Period. But the way Trevor talks about them seems to imply that it is more complex. He cites the following code, and explains that when the function FrmGetObjectIndex dereferences f, it isn’t accessing a valid pointer, but rather an unpredictable address — whatever was on the stack when the space for f was allocated. What does Trevor mean by "whatever was on the stack when the space for f was allocated"? Are "un-initialized" pointers initialized to random locations in memory by default? Or does their "random" behavior have to do with the memory allocated for these pointers getting filled with strange values (that are then referenced) because of unexpected behavior on the stack. Form *f; switch (event->eType) { case frmOpenEvent: f = FrmGetActiveForm(); ... case ctlSelectEvent: i = FrmGetObjectIndex(f, field); ... }

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  • C programming: Dereferencing pointer to incomplete type error

    - by confusedKid
    Hi, I am pretty rusty at C, and I'm getting a dereferencing error. Hopefully someone can help me with this? ^_^ I have a struct defined as: struct { char name[32]; int size; int start; int popularity; } stasher_file; and an array of pointers to those structs: struct stasher_file *files[TOTAL_STORAGE_SIZE]; In my code, I'm making a pointer to the struct and setting its members, and adding it to the array: ... struct stasher_file *newFile; strncpy(newFile-name, name, 32); newFile-size = size; newFile-start = first_free; newFile-popularity = 0; files[num_files] = newFile; ... I'm getting a "error: dereferencing pointer to incomplete type" whenever I try to access the members inside newFile. What am I doing wrong? Thanks very much for any help :)

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  • Get Function Pointer to function in a shared library I didn't directly load

    - by bdk
    My Linux application (A) links against a Third Party shared Library (B) which I don't have source code to. This library makes use of another third party shared library that I don't have source code to (C). I believe that (B) uses dlopen to access (C) instead of directly linking. My reasoning for this is that 'ldd' on (B) does not show (C) and objdump -X (B) shows references to dlopen/dlclose/dlsym. My requirement is that I need to in my code for (A) get a function pointer to a function foo() located in (C). Normally I'd use dlsym for this, but I need to pass it the handle returned from dlopen which I don't have since (B) does not expose this. - For the larger context: I need to modify the function in (C) such that everytime it calls its helper function bar() (also located in (C)), it also calls a function with the same signature located in (A) with the same parameters (Basically inject my code into the codepath of (C) foo()-bar(). I believe I've found a way to accomplish this using gdb, but in order to port my gdb command list, but I'm stuck on the step of getting the function pointer. I'm also open to alternatives to accomplish the same task rather than the exact problem as stated above Edit: After writing this I realized I can probably just do another dlopen on the file in my code and the symbols returned via dlsym on that handle should be the same as received via the original dlopen, If I'm reading the dlopen man page correctly. However I'm still interested in advice or assistance with the my larger context, If theres a better way to go about this

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  • Getting value from pointer

    - by Eric
    Hi, I'm having problem getting the value from a pointer. I have the following code in C++: void* Nodo::readArray(VarHash& var, string varName, int posicion, float& d) { //some code before... void* res; float num = bit.getFloatFromArray(arregloTemp); //THIS FUNCTION RETURN A FLOAT AND IT'S OK cout << "NUMBER " << num << endl; d = num; res = &num; return res } int main() { float d = 0.0; void* res = n.readArray(v, "c", 0, d); //THE VALUES OF THE ARRAY ARE: {65.5, 66.5}; float* car3 = (float*)res; cout << "RESULT_READARRAY " << *car3 << endl; cout << "FLOAT REFERENCE: " << d << endl; } The result of running this code is the following: NUMBER 65.5 RESULT_READARRAY -1.2001 //INCORRECT IT SHOULD BE LIKE NUMBER FLOAT REFERENCE: 65.5 //CORRECT NUMBER 66.5 RESULT_READARRAY -1.2001 //INCORRECT IT SHOULD BE LIKE NUMBER FLOAT REFERENCE: 66.5 //CORRECT For some reason, when I get the value of the pointer returned by the function called readArray is incorrect. I'm passing a float variable(d) as a reference in the same function just to verify that the value is ok, and as you can see, THE FLOAT REFERENCE matches the NUMBER. If I declare the variable num(read array) as a static float, the first RESULT_READARRAY will be 65.5, that is correct, however, the next value will be the same instead of 66.5. Let me show you the result of running the code using static float variable: NUMBER 65.5 RESULT_READARRAY 65.5 //PERFECT FLOAT REFERENCE: 65.5 //¨PERFECT NUMBER 65.5 //THIS IS INCORRECT, IT SHOULD BE 66.5 RESULT_READARRAY 65.5 FLOAT REFERENCE: 65.5 Do you know how can I get the correct value returned by the function called readArray()?

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  • What is the merit of the "function" type (not "pointer to function")

    - by anatolyg
    Reading the C++ Standard, i see that there are "function" types and "pointer to function" types: typedef int func(int); // function typedef int (*pfunc)(int); // pointer to function typedef func* pfunc; // same as above I have never seen the function types used outside of examples (or maybe i didn't recognize their usage?). Some examples: func increase, decrease; // declares two functions int increase(int), decrease(int); // same as above int increase(int x) {return x + 1;} // cannot use the typedef when defining functions int decrease(int x) {return x - 1;} // cannot use the typedef when defining functions struct mystruct { func add, subtract, multiply; // declares three member functions int member; }; int mystruct::add(int x) {return x + member;} // cannot use the typedef int mystruct::subtract(int x) {return x - member;} int main() { func k; // the syntax is correct but the variable k is useless! mystruct myobject; myobject.member = 4; cout << increase(5) << ' ' << decrease(5) << '\n'; // outputs 6 and 4 cout << myobject.add(5) << ' ' << myobject.subtract(5) << '\n'; // 9 and 1 } Seeing that the function types support syntax that doesn't appear in C (declaring member functions), i guess they are not just a part of C baggage that C++ has to support for backward compatibility. So is there any use for function types, other than demonstrating some funky syntax?

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  • Strict pointer aliasing: is access through a 'volatile' pointer/reference a solution?

    - by doublep
    On the heels of a specific problem, a self-answer and comments to it, I'd like to understand if it is a proper solution, workaround/hack or just plain wrong. Specifically, I rewrote code: T x = ...; if (*reinterpret_cast <int*> (&x) == 0) ... As: T x = ...; if (*reinterpret_cast <volatile int*> (&x) == 0) ... with a volatile qualifier to the pointer. Let's just assume that treating T as int in my situation makes sense. Does this accessing through a volatile reference solve pointer aliasing problem? For a reference, from specification: [ Note: volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation. See 1.9 for detailed semantics. In general, the semantics of volatile are intended to be the same in C++ as they are in C. — end note ] EDIT: The above code did solve my problem at least on GCC 4.5.

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  • Understanding C++ pointers (when they point to a pointer)

    - by Stephano
    I think I understand references and pointers pretty well. Here is what I (think I) know: int i = 5; //i is a primitive type, the value is 5, i do not know the address. int *ptr; //a pointer to an int. i have no way if knowing the value yet. ptr = &i; //now i have an address for the value of i (called ptr) *ptr = 10; //go get the value stored at ptr and change it to 10 Please feel free to comment or correct these statements. Now I'm trying to make the jump to arrays of pointers. Here is what I do not know: char **char_ptrs = new char *[50]; Node **node_ptrs = new Node *[50]; My understanding is that I have 2 arrays of pointers, one set of pointers to chars and one to nodes. So if I wanted to set the values, I would do something like this: char_ptrs[0] = new char[20]; node_ptrs[0] = new Node; Now I have a pointer, in the 0 position of my array, in each respective array. Again, feel free to comment here if I'm confused. So, what does the ** operator do? Likewise, what is putting a single * next to the instantiation doing (*[50])? (what is that called exactly, instantiation?)

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  • Does Function pointer make the program slow?

    - by drigoSkalWalker
    Hi guys. I read about function pointers in C And everyone said that will make my program run slow. Is it true? I made a program to check it. And I got the same results on both cases. (mesure the time.) So, is it bad to use fuction pointer? Thanks in advance. To response for some guys. I said 'run slow' for the time that I have compared on a loop. like this. int end = 1000; int i = 0; while (i < end) { fp = func; fp (); } When you execute this, i got the same time if I execute this. while (i < end) { func (); } So I think that function pointer have no difference of time and it don't make a program run slow as many people said.

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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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  • Static member function pointer to hold non static member function

    - by user1425406
    This has defeated me. I want to have a static class variable which is a pointer to a (non-static) member function. I've tried all sorts of ways, but with no luck (including using typedefs, which just seemed to give me a different set of errors). In the code below I have the static class function pointer funcptr, and I can call it successfully from outside the class, but not from within the member function CallFuncptr - which is what I want to do. Any suggestions? #include <stdio.h> class A { public: static int (A::*funcptr)(); int Four() { return 4;}; int CallFuncptr() { return (this->*funcptr)(); } // doesn't link - undefined reference to `A::funcptr' }; int (A::*funcptr)() = &A::Four; int main() { A fred; printf("four? %d\n", (fred.*funcptr)()); // This works printf("four? %d\n", fred.CallFuncptr()); // But this is the way I want to call it }

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  • Invalid Pointer Operation, advice requested with debugging

    - by Xanyx
    I appear to have created code that is trashing memory. Having never had such problems before, i am now settign an Invalid Pointer Operation. In the following the value of the const string sFilename gets trashed after my call to PromptForXYZPropertiesSettings. // Allow the user to quickly display the properties of XYZ without needing to display the full Editor function PromptForXYZProperties(const sFilename:string; var AXYZProperties: TXYZProperties): boolean; var PropEditor: TdlgEditor; begin PropEditor:= TdlgEditor.create(nil); try PropEditor.LoadFromFile(sFilename); Other Details: Delphi 2007, Windows 7 64 bit, but can reproduce when testing EXE on XP REMOVING CONST STOPS PROBLEM FROM EXHIBITING (but presumably the problem is thus just lurking) PropEditor.PromptForXYZPropertiesSettings creates and shows a form. If I disable the ShowModal call then the memory is not trashed. Even though i have REMOVED ALL CONTROLS AND CODE from the form So I would like some advice on how to debug the issue. I was thinking perhaps watching the memory pointer where the sFilename var exists to see where it gets trashed, but not sure how i would do that (obviously needs to be done within the app so is owned memory). Thanks

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  • pointer, malloc and char in C

    - by user2534078
    im trying to copy a const char array to some place in the memory and point to it . lets say im defining this var under the main prog : char *p = NULL; and sending it to a function with a string : myFunc(&p, "Hello"); now i want that at the end of this function the pointer will point to the letter H but if i puts() it, it will print Hello . here is what i tried to do : void myFunc(char** ptr , const char strng[] ) { *ptr=(char *) malloc(sizeof(strng)); char * tmp=*ptr; int i=0; while (1) { *ptr[i]=strng[i]; if (strng[i]=='\0') break; i++; } *ptr=tmp; } i know its a rubbish now, but i would like to understand how to do it right, my idea was to allocate the needed memory, copy a char and move forward with the pointer, etc.. also i tried to make the ptr argument byreferenec (like &ptr) but with no success due to a problem with the lvalue and rvalue . the only thing is changeable for me is the function, and i would like not to use strings, but chars as this is and exercise . thanks for any help in advance.

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  • C++ ulong to class method pointer and back

    - by Simone Margaritelli
    Hi guys, I'm using a hash table (source code by Google Inc) to store some method pointers defined as: typedef Object *(Executor::*expression_delegate_t)( vframe_t *, Node * ); Where obviously "Executor" is the class. The function prototype to insert some value to the hash table is: hash_item_t *ht_insert( hash_table_t *ht, ulong key, ulong data ); So basically i'm doing the insert double casting the method pointer: ht_insert( table, ASSIGN, reinterpret_cast<ulong>( (void *)&Executor::onAssign ) ); Where table is defined as a 'hash_table_t *' inside the declaration of the Executor class, ASSIGN is an unsigned long value, and 'onAssign' is the method I have to map. Now, Executor::onAssign is stored as an unsigned long value, its address in memory I think, and I need to cast back the ulong to a method pointer. But this code: hash_item_t* item = ht_find( table, ASSIGN ); expression_delegate_t delegate = reinterpret_cast < expression_delegate_t > (item->data); Gives me the following compilation error : src/executor.cpp:45: error: invalid cast from type ‘ulong’ to type ‘Object* (Executor::*)(vframe_t*, Node*)’ I'm using GCC v4.4.3 on a x86 GNU/Linux machine. Any hints?

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  • Pointer-Safe Objects?

    - by cam
    Would it be smart to have a vector in an object with a list of pointers that point to it? This way when the object is deleted, it could delete all the pointers pointing to it to prevent a null-pointer exception?

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  • Cannot Convert from int[][] to int*

    - by cam
    I have a 3x3 array that I'm trying to create a pointer to and I keep getting this array, what gives? How do I have to define the pointer? I've tried every combination of [] and *. Is it possible to do this? int* pTemp = tempSec;

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  • How to get Ponter/Reference semantics in Scala.

    - by Lukasz Lew
    In C++ I would just take a pointer (or reference) to arr[idx]. In Scala I find myself creating this class to emulate a pointer semantic. class SetTo (val arr : Array[Double], val idx : Int) { def apply (d : Double) { arr(idx) = d } } Isn't there a simpler way? Doesn't Array class have a method to return some kind of reference to a particular field?

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  • WPF ToolBar: how to customize appearance (remove dots and a pointer)

    - by Nike
    I use ToolBar for my WPF application. As I understand, there is no easy way to make it floating. I just want to remove elements which I don't want to be displayed: several dots in the left side, and a pointer (arrow) in right side of ToolBar. Is there any Properties to customize view of ToolBar? Or, maybe, it's possible to redefine a ToolBar Template?

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  • SQLiteOpenHelper.getWriteableDatabase() null pointer exception on Android

    - by Drew Dara-Abrams
    I've had fine luck using SQLite with straight, direct SQL in Android, but this is the first time I'm wrapping a DB in a ContentProvider. I keep getting a null pointer exception when calling getWritableDatabase() or getReadableDatabase(). Is this just a stupid mistake I've made with initializations in my code or is there a bigger issue? public class DatabaseProvider extends ContentProvider { ... private DatabaseHelper databaseHelper; private SQLiteDatabase db; ... @Override public boolean onCreate() { databaseHelper = new DatabaseProvider.DatabaseHelper(getContext()); return (databaseHelper == null) ? false : true; } ... @Override public Uri insert(Uri uri, ContentValues values) { db = databaseHelper.getWritableDatabase(); // NULL POINTER EXCEPTION HERE ... } private static class DatabaseHelper extends SQLiteOpenHelper { public static final String DATABASE_NAME = "cogsurv.db"; public static final int DATABASE_VERSION = 1; public static final String[] TABLES = { "people", "travel_logs", "travel_fixes", "landmarks", "landmark_visits", "direction_distance_estimates" }; // people._id does not AUTOINCREMENT, because it's set based on server's people.id public static final String[] CREATE_TABLE_SQL = { "CREATE TABLE people (_id INTEGER PRIMARY KEY," + "server_id INTEGER," + "name VARCHAR(255)," + "email_address VARCHAR(255))", "CREATE TABLE travel_logs (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "start DATE," + "stop DATE," + "type VARCHAR(15)," + "uploaded VARCHAR(1))", "CREATE TABLE travel_fixes (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "datetime DATE, " + "latitude DOUBLE, " + "longitude DOUBLE, " + "altitude DOUBLE," + "speed DOUBLE," + "accuracy DOUBLE," + "travel_mode VARCHAR(50), " + "person_local_id INTEGER," + "person_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE landmarks (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "name VARCHAR(150)," + "latitude DOUBLE," + "longitude DOUBLE," + "person_local_id INTEGER," + "person_server_id INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE landmark_visits (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "landmark_local_id INTEGER," + "landmark_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "datetime DATE," + "number_of_questions_asked INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE direction_distance_estimates (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "landmark_visit_local_id INTEGER," + "landmark_visit_server_id INTEGER," + "start_landmark_local_id INTEGER," + "start_landmark_server_id INTEGER," + "target_landmark_local_id INTEGER," + "target_landmark_server_id INTEGER," + "datetime DATE," + "direction_estimate DOUBLE," + "distance_estimate DOUBLE," + "uploaded VARCHAR(1))" }; public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); Log.v(Constants.TAG, "DatabaseHelper()"); } @Override public void onCreate(SQLiteDatabase db) { Log.v(Constants.TAG, "DatabaseHelper.onCreate() starting"); // create the tables int length = CREATE_TABLE_SQL.length; for (int i = 0; i < length; i++) { db.execSQL(CREATE_TABLE_SQL[i]); } Log.v(Constants.TAG, "DatabaseHelper.onCreate() finished"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { for (String tableName : TABLES) { db.execSQL("DROP TABLE IF EXISTS" + tableName); } onCreate(db); } } } As always, thanks for the assistance! -- Not sure if this detail helps, but here's LogCat showing the exception:

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  • Pointer to NSWindow Xib after loading it?

    - by Brock Woolf
    In my code below, CustomWindow is a subclass of NSWindow. CustomWindow *window = [[CustomWindow alloc] init]; if (![NSBundle loadNibNamed:@"NibName" owner:window]) [window center]; // doesn't work How do you get a pointer to control your XIB after you load it so you can do things such as centering the XIB? What am i doing wrong here?

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  • "this" pointer changes in GDB backtrace

    - by Hans
    I am examining a core dump, and noticed that in one frame the 'this' pointer is different than in the next frame (in the same thread). Not just a little different, it went from 0x8167428 to 0x200. I am not that well-versed in using GDB, but this does not seem right to me. Is this problematic, and if so, what could be the cause?

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  • passing argument 1 from incompatible pointer type

    - by Andrew
    Why does this code...: NSDictionary *testDictionary = [NSDictionary dictionaryWithObjectsAndKeys:kABOtherLabel, @"other", kABWorkLabel, @"work", nil]; throw this warning: warning: passing argument 1 of 'dictionaryWithObjectsAndKeys' from incompatible pointer type Incidentally, the code works as expected, but I don't like leaving warnings un-delt-with. I assume it doesn't like that I'm storing a constant in a dictionary. Well, where can I store it then? Should I just place (void *) before every constant?

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