Search Results

Search found 3255 results on 131 pages for 'pointers'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 26/131 | < Previous Page | 22 23 24 25 26 27 28 29 30 31 32 33  | Next Page >

  • system crash after declaring global object of the class

    - by coming out of void
    hi, i am very new to c++. i am getting system crash (not compilation error) in doing following: i am declaring global pointer of class. BGiftConfigFile *bgiftConfig; class BGiftConfigFile : public EftBarclaysGiftConfig { } in this class i am reading tags from xml file. it is crashing system when this pointer is used to retrieve value. i am doing coding for verifone terminal. int referenceSetting = bgiftConfig->getreferencesetting(); //system error getreferencesetting() is member fuction of class EftBarclaysGiftConfig i am confused about behavior of pointer in this case. i know i am doing something wrong but couldn't rectify it. When i declare one object of class locally it retrieves the value properly. BGiftConfigFile bgiftConfig1; int referenceSetting = bgiftConfig1->getreferencesetting(); //working But if i declare this object global it also crashes the system. i need to fetch values at different location in my code so i forced to use someting global. please suggest me how to rectify this problem.

    Read the article

  • (gcc) Multi-Dim Array or Double Pointer for Warning-free Compile

    - by paul simmons
    Hi, I have a function, which is called sometimes with regular, sometimes dynamic arrays. If I define the function as function_name(int[10][10] a) and send int** as a parameter, I get a warning. Opposite, if I declare function_name(int** a) and send int[][] as a parameter (after casting) I cannot access to array elements inside function. What is the correctest way?

    Read the article

  • How to call shared_ptr<boost::signal> from a vector in a loop?

    - by BTR
    I've got a working callback system that uses boost::signal. I'm extending it into a more flexible and efficient callback manager which uses a vector of shared_ptr's to my signals. I've been able to successfully create and add callbacks to the list, but I'm unclear as to how to actually execute the signals. ... // Signal aliases typedef boost::signal<void (float *, int32_t)> Callback; typedef std::shared_ptr<Callback> CallbackRef; // The callback list std::vector<CallbackRef> mCallbacks; // Adds a callback to the list template<typename T> void addCallback(void (T::* callbackFunction)(float * data, int32_t size), T * callbackObject) { CallbackRef mCallback = CallbackRef(new Callback()); mCallback->connect(boost::function<void (float *, int32_t)>(boost::bind(callbackFunction, callbackObject, _1, _2))); mCallbacks.push_back(mCallback); } // Pass the float array and its size to the callbacks void execute(float * data, int32_t size) { // Iterate through the callback list for (vector<CallbackRef>::iterator i = mCallbacks.begin(); i != mCallbacks.end(); ++i) { // What do I do here? // (* i)(data, size); // <-- Dereferencing doesn't work } } ... All of this code works. I'm just not sure how to run the call from within a shared_ptr from with a vector. Any help would be neat-o. Thanks, in advance.

    Read the article

  • C String input confusion

    - by ahref
    C really isn't my strong point and after reading 3 chapters of a book on the subject and spending ages trying to get stuff working it just doesn't: #include <stdio.h> char *a,*b; int main( ) { char input[10]; fgets(input,sizeof input, stdin); a = input; fgets(input,sizeof input, stdin); b = input; printf("%s : %s",a,b); } I've isolated the problem from my main project. This code is meant to read in two strings and then print them however it seems to be setting a and b to point to input. Sample output from this code when A and B are entered is(don't worry about the \n's i can remove them): A B B : B How do i store the value of input in another variable eg. a or b so that in the above case A B A : B Is output? Thanks

    Read the article

  • Pointer inside a struct / thread

    - by bruno
    Hi! I have this warning "warning: assignment from incompatible pointer type " in this line: data1->transformed_block[l] = &transformed_block[l]; - void print_message_function ( void *ptr ) { dt *data; data = (dt *) ptr; printf("Dentro da thread Numero0: %ld\n", data->L_norm_NewBlock); pthread_exit(0); } typedef struct data_thread { long L_norm_NewBlock; int Bsize_X; int Bsize_Y; int *transformed_block[MAX_LEVEL]; long L_norm_OrigBlock; } dt; void function() { int *transformed_block[MAX_LEVEL]; pthread_t thread1; dt *data1; pthread_attr_t attr; pthread_attr_init(&attr); //Fills structure data1 = (dt *) malloc(sizeof(dt)); data1->transformed_block[l] = &transformed_block[l]; data1->L_norm_NewBlock=0; data1->Bsize_Y = Bsize_Y; data1->Bsize_X = Bsize_X; pthread_create(&thread1, &attr, (void *) &print_message_function, (void *) &data1); } I want to get rid of that warning, and the values i get inside the thread are wrong. For example data1-L_norm_NewBlock=0; in the thread guives me a differente value (not 0 like it should be).

    Read the article

  • Detect pointer arithmetics because of LARGEADDRESSAWARE

    - by Suma
    I would like to switch my application to LARGEADDRESSAWARE. One of issues to watch for is pointer arithmetic, as pointer difference can no longer be represented as signed 32b. Is there some way how to find automatically all instances of pointer subtraction in a large C++ project? If not, is there some "least effort" manual or semi-automatic method how to achieve this?

    Read the article

  • pointer pointer

    - by gcc
    why we using double pointer like char **p; are there any purpose ,if there is please tell me i read some books but none of them tells purpose(s) of pointer to pointer if we can write char *p; and char **p; i think we may write char ***p; or char ****p; am i wrong

    Read the article

  • Alternatives to C++ Reference/Pointer Syntax

    - by Jon Purdy
    What languages other than C and C++ have explicit reference and pointer type qualifiers? People seem to be easily confused by the right-to-left reading order of types, where char*& is "a reference to a pointer to a character", or a "character-pointer reference"; do any languages with explicit references make use of a left-to-right reading order, such as &*char/ref ptr char? I'm working on a little language project, and legibility is one of my key concerns. It seems to me that this is one of those questions to which it's easy for a person but hard for a search engine to provide an answer. Thanks in advance!

    Read the article

  • Cryptic C++ "thing" (function pointer)

    - by m00st
    What is this syntax for in C++? Can someone point me to the technical term so I can see if I find anything in my text? At first I thought it was a prototype but then the = and (*fn) threw me off... Here is my example: void (*fn) (int&,int&) = x;

    Read the article

  • Problem with Command Pattern under Visual Studio 2008 (C++)

    - by D.Giunchi
    Dear All, I've a problem with this pattern under c++ on VS 2008. The same code has been tested in gcc (linux, mac and mingw for widnows) and it works. I copy/paste the code here: class MyCommand { public: virtual void execute() = 0; virtual ~MyCommand () {}; }; class MyOperation { public: virtual void DoIt() {}; //I also write it not inline }; class MyOperationDerived : public MyOperation { public: virtual void DoIt() {}; //I also write it not inline }; class MyUndoStackCommand : public MyCommand { public: typedef void(MyOperation::*Action)(); MyUndoStackCommand(MyOperation *rec, Action action); /*virtual*/ void execute(); /*virtual*/ ~MyUndoStackCommand(); private: MyOperation *myReceiver; Action myAction ; }; in cpp: #include "MyUndoStackCommand.h" #include "MyOperation.h" MyUndoStackCommand::~MyUndoStackCommand() { } MyUndoStackCommand::MyUndoStackCommand(myOperation *rec, Action action): myReceiver(rec), myAction(action) { } void MyUndoStackCommand::execute() { ((myReceiver)->*(myAction))(); } use in main.cpp: MyReceiver receiver; MyUndoStackCommand usc(&receiver, &MyOperation::DoIt); usc.execute(); when I debug under visual studio only if I set inside MyUndoStackCommand, directly myAction = &MyOperation::DoIt , it works, otherwise not. Any advice? thank you very much, dan Edit: The following code compiles with g++ - changes by Neil Butterworth flagged as //NB. class MyCommand { public: virtual void execute() = 0; virtual ~MyCommand () {}; }; class MyOperation { public: virtual void DoIt() {}; //I also write it not inline }; class MyOperationDerived : public MyOperation { public: virtual void DoIt() {}; //I also write it not inline }; class MyUndoStackCommand : public MyCommand { public: typedef void(MyOperation::*Action)(); MyUndoStackCommand(MyOperation *rec, Action action); /*virtual*/ void execute(); /*virtual*/ ~MyUndoStackCommand(); private: MyOperation *myReceiver; Action myAction ; }; MyUndoStackCommand::~MyUndoStackCommand() { } MyUndoStackCommand::MyUndoStackCommand(MyOperation *rec, //NB Action action) : myReceiver(rec), myAction(action) { } void MyUndoStackCommand::execute() { ((myReceiver)->*(myAction))(); } int main() { MyOperation receiver; //NB MyUndoStackCommand usc(&receiver, &MyOperation::DoIt); usc.execute(); }

    Read the article

  • C++ arrays as parameters, EDIT: now includes variable scoping

    - by awshepard
    Alright, I'm guessing this is an easy question, so I'll take the knocks, but I'm not finding what I need on google or SO. I'd like to create an array in one place, and populate it inside a different function. I define a function: void someFunction(double results[]) { for (int i = 0; i<100; ++i) { for (int n = 0; n<16; ++n) //note this iteration limit { results[n] += i * n; } } } That's an approximation to what my code is doing, but regardless, shouldn't be running into any overflow or out of bounds issues or anything. I generate an array: double result[16]; for(int i = 0; i<16; i++) { result[i] = -1; } then I want to pass it to someFunction someFunction(result); When I set breakpoints and step through the code, upon entering someFunction, results is set to the same address as result, and the value there is -1.000000 as expected. However, when I start iterating through the loop, results[n] doesn't seem to resolve to *(results+n) or *(results+n*sizeof(double)), it just seems to resolve to *(results). What I end up with is that instead of populating my result array, I just get one value. What am I doing wrong? EDIT Oh fun, I have a typo: it wasn't void someFunction(double results[]). It was: void someFunction(double result[])... So perhaps this is turning into a scoping question. If my double result[16] array is defined in a main.cpp, and someFunction is defined in a Utils.h file that's included by the main.cpp, does the result variable in someFunction then wreak havoc on the result array in main?

    Read the article

  • Problem with pointer copy in C

    - by Stefano Salati
    I radically re-edited the question to explain better my application, as the xample I made up wasn't correct in many ways as you pointed out: I have one pointer to char and I want to copy it to another pointer and then add a NULL character at the end (in my real application, the first string is a const, so I cannot jsut modify it, that's why I need to copy it). I have this function, "MLSLSerialWriteBurst" which I have to fill with some code adapt to my microcontroller. tMLError MLSLSerialWriteBurst( unsigned char slaveAddr, unsigned char registerAddr, unsigned short length, const unsigned char *data ) { unsigned char *tmp_data; tmp_data = data; *(tmp_data+length) = NULL; // this function takes a tmp_data which is a char* terminated with a NULL character ('\0') if(EEPageWrite2(slaveAddr,registerAddr,tmp_data)==0) return ML_SUCCESS; else return ML_ERROR; } I see there's a problem here: tha fact that I do not initialize tmp_data, but I cannot know it's length.

    Read the article

  • Adding and sorting a linked list in C

    - by user1202963
    In my assignment, I have to write a function that takes as arguments a pointer to a "LNode" structure and an integer argument. Then, I have to not only add that integer into the linked list, but also put place it so that the list is in proper ascending order. I've tried several various attempts at this, and this is my code as of posting. LNode* AddItem(LNode *headPtr, int newItem) { auto LNode *ptr = headPtr; ptr = malloc(sizeof(LNode)); if (headPtr == NULL) { ptr->value = newItem; ptr->next = headPtr; return ptr; } else { while (headPtr->value > newItem || ptr->next != NULL) { printf("While\n"); // This is simply to let me know how many times the loop runs headPtr = headPtr->next; } ptr->value = newItem; ptr->next = headPtr; return ptr; } } // end of "AddItem" When I run it, and try to insert say a 5 and then a 3, the 5 gets inserted, but then the while loop runs once and I get a segmentation fault. Also I cannot change the arguments as it's part of a skeletal code for this project. Thanks to anyone who can help. If it helps this is what the structure looks like typedef struct LNode { int value; struct LNode *next; } LNode;

    Read the article

  • Access array of c-structs using Python ctypes

    - by sadris
    I have a C-function that allocates memory at the address passed to and is accessed via Python. The pointer contents does contain an array of structs in the C code, but I am unable to get ctypes to access the array properly beyond the 0th element. How can I get the proper memory offset to be able to access the non-zero elements? Python's ctypes.memset is complaining about TypeErrors if I try to use their ctypes.memset function. typedef struct td_Group { unsigned int group_id; char groupname[256]; char date_created[32]; char date_modified[32]; unsigned int user_modified; unsigned int user_created; } Group; int getGroups(LIBmanager * handler, Group ** unallocatedPointer); ############# python code below: class Group(Structure): _fields_ = [("group_id", c_uint), ("groupname", c_char*256), ("date_created", c_char*32), ("date_modified", c_char*32), ("user_modified", c_uint), ("user_created", c_uint)] myGroups = c_void_p() count = libnativetest.getGroups( nativePointer, byref(myGroups) ) casted = cast( myGroups, POINTER(Group*count) ) for x in range(0,count): theGroup = cast( casted[x], POINTER(Group) ) # this only works for the first entry in the array: print "~~~~~~~~~~" + theGroup.contents.groupname Related: Access c_char_p_Array_256 in Python using ctypes

    Read the article

  • C++ dynamic array causes segmentation fault at assigment

    - by opc0de
    I am doing a application witch uses sockets so I am holding in an array the sockets handles.I have the following code: while(0 == 0){ int * tx = (int*)(malloc((nr_con + 2) * sizeof(int))); if (conexiuni != NULL) { syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con); memcpy(&tx[0],&conexiuni[0],(sizeof(int) * (nr_con))); syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con); free(conexiuni); } conexiuni = tx; syslog(LOG_NOTICE,"Ajung la mama %d",nr_con); //The line bellow causes a segfault at second connection if ((conexiuni[nr_con] = accept(hsock,(sockaddr*)(&sadr),&addr_size)) != -1) { nr_con++; syslog(LOG_NOTICE,"Primesc de la %s",inet_ntoa(sadr.sin_addr)); syslog(LOG_NOTICE,"kkt %d",conexiuni[nr_con - 1]); int * sz = (int*)malloc(sizeof(int)); *sz = conexiuni[nr_con - 1]; syslog(LOG_NOTICE,"after %d",*sz); pthread_create(&tidi,0,&ConexiuniHandler, sz); } } When I connect the second time when I assign the array the program crashes. What am I doing wrong? I tried the same code on Windows and it works well but on Linux it crashes.

    Read the article

  • NULL pointer dereference in C

    - by user554125
    hey ive got this piece of code. It dereferences a null pointer here. But then there is an and with unsigned int. I really dont understand the whole part. Can someone explain the output.?? struct hi { long a; int b; long c; }; int main() { struct hi ob={3,4,5}; struct hi *ptr=&ob; int num= (unsigned int) & (((struct hi *)0)->b); printf("%d",num); printf("%d",*(int *)((char *)ptr + (unsigned int) & (((struct hi *)0)->b))); } The o/p i get is 44 .But how does it work?

    Read the article

  • Typcast a null pointer to char*

    - by user326253
    Suppose I have a char* elem that is supposed to hold a char*, s.t. elem[0] = char*, elem[1...m]= more chars. Is there a way I can put a null ptr within char* elem? When I try to set elem = NULL, it gives me a type error because NULL is an int. Any help would be greatly appreciated!

    Read the article

  • Accessing any structs members at run-time.

    - by jmgunn
    Is it possible to get access to an individual member of a struct or class without knowing the names of its member variables? I would like to do an "offsetof(struct, tyname)" without having the struct name or member variable name hard coded amoungst other things. thanks.

    Read the article

  • C++, using one byte to store two variables

    - by 2di
    Hi All I am working on representation of the chess board, and I am planning to store it in 32 bytes array, where each byte will be used to store two pieces. (That way only 4 bits are needed per piece) Doing it in that way, results in a overhead for accessing particular index of the board. Do you think that, this code can be optimised or completely different method of accessing indexes can be used? c++ char getPosition(unsigned char* c, int index){ //moving pointer c+=(index>>1); //odd number if (index & 1){ //taking right part return *c & 0xF; }else { //taking left part return *c>>4; } } void setValue(unsigned char* board, char value, int index){ //moving pointer board+=(index>>1); //odd number if (index & 1){ //replace right part //save left value only 4 bits *board = (*board & 0xF0) + value; }else { //replacing left part *board = (*board & 0xF) + (value<<4); } } int main() { char* c = (char*)malloc(32); for (int i = 0; i < 64 ; i++){ setValue((unsigned char*)c, i % 8,i); } for (int i = 0; i < 64 ; i++){ cout<<(int)getPosition((unsigned char*)c, i)<<" "; if (((i+1) % 8 == 0) && (i > 0)){ cout<<endl; } } return 0; } I am equally interested in your opinions regarding chess representations, and optimisation of the method above, as a stand alone problem. Thanks a lot

    Read the article

  • List<MyClass*> & array question

    - by Nano HE
    Hi, Assuming a definition like this, list<MyCommand*> subList ... MyCommand* pCmd = (MyCommand*)(m_treeSM.GetItemData(node)); I tried these statements below, but failed. pCmd->subList[2] (pCmd->subList)[2] How can I get the array member values(such as subList[2]). I want to replace the value of subList[2] with other same type value. Thank you.

    Read the article

  • Does this have anything to do with endian-ness?

    - by eSKay
    This piece of code: #include<stdio.h> void hello() { printf("hello\n"); } void bye() { printf("bye\n"); } int main() { printf("%p\n", hello); printf("%p\n", bye); return 0; } output on my machine: 0x80483f4 0x8048408 [second address is bigger in value] on Codepad 0x8048541 0x8048511 [second address is smaller in value] Does this have anything to do with endian-ness of the machines? If not, Why the difference in the ordering of the addresses? Also, Why the difference in the difference? 0x8048541 - 0x8048511 = 0x30 0x8048408 - 0x80483f4 = 0x14 Btw, I just checked. This code (taken from here) says that both the machines are Little-Endian #include<stdio.h> int main() { int num = 1; if(*(char *)&num == 1) printf("Little-Endian\n"); else printf("Big-Endian\n"); return 0; }

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 22 23 24 25 26 27 28 29 30 31 32 33  | Next Page >