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dlete pointer.

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  • S see me

    When ever i try to delete a pointer exception is occuring. if any reson for this?????:confused: yours faithfully ajeeshcv

    J Offline
    J Offline
    John R Shaw
    wrote on last edited by
    #5

    You need to be more specific, what do you mean by delete a pointer? I assume memory pointer, but these days it is hard to say. What compiler of language are you using? INTP "Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

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    • S see me

      no...i tried to delete it after checking.:(( if( pPointer ) { delete pPointer; pPointer = 0; } yours faithfully ajeeshcv

      T Offline
      T Offline
      toxcct
      wrote on last edited by
      #6

      and what is the error ?????


      TOXCCT >>> GEII power

      [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

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      • S see me

        no...i tried to delete it after checking.:(( if( pPointer ) { delete pPointer; pPointer = 0; } yours faithfully ajeeshcv

        C Offline
        C Offline
        Cedric Moonen
        wrote on last edited by
        #7

        What is the exact error ? Maybe your pointer points to an invalid address. You probably left it uninitialized and then try to delete it.


        Cédric Moonen Software developer
        Charting control

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        • V Viorel

          Possible causes:

          • un-initialized pointer, like int * p; delete p;
          • pointer does not point to an object created with new: int x; int * p = &x; delete p;
          • multiple execution of delete: int * p = new int; delete p; delete p;
          • pointed zone was altered by other code: int * p = new int; memset(p-100, 0, 1000); delete p;
            Note that null value of pointer does not generate exception. This is OK: int * p = NULL; delete p; -- modified at 3:58 Wednesday 14th June, 2006
          S Offline
          S Offline
          see me
          wrote on last edited by
          #8

          In my case the above mentioned 4 cases will not be satisfied. Actual reason is any other.:-> And also as per ur comments int * p = NULL; delete p; how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.:confused: yours faithfully ajeeshcv

          T C V 3 Replies Last reply
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          • T toxcct

            and what is the error ?????


            TOXCCT >>> GEII power

            [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

            S Offline
            S Offline
            see me
            wrote on last edited by
            #9

            exception is occuring. yours faithfully ajeeshcv

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            • S see me

              When ever i try to delete a pointer exception is occuring. if any reson for this?????:confused: yours faithfully ajeeshcv

              H Offline
              H Offline
              Hamid Taebi
              wrote on last edited by
              #10

              Can you show how to use pointer and how to declare pointer_**


              **_

              whitesky


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              • S see me

                exception is occuring. yours faithfully ajeeshcv

                C Offline
                C Offline
                Cedric Moonen
                wrote on last edited by
                #11

                That's a very clear description of the problem :~ The solution is: you did something wrong.


                Cédric Moonen Software developer
                Charting control

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                • S see me

                  exception is occuring. yours faithfully ajeeshcv

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                  toxcct
                  wrote on last edited by
                  #12

                  Ajeesh c v wrote:

                  exception is occuring.

                  DAMNNNNN !!! WHICHHHH ????? if you don't provide some descriptions of your error case, how can one help you ?? :~ :mad:


                  TOXCCT >>> GEII power

                  [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

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                  • S see me

                    In my case the above mentioned 4 cases will not be satisfied. Actual reason is any other.:-> And also as per ur comments int * p = NULL; delete p; how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.:confused: yours faithfully ajeeshcv

                    T Offline
                    T Offline
                    toxcct
                    wrote on last edited by
                    #13

                    Ajeesh c v wrote:

                    int * p = NULL; delete p; how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.

                    he doesn't say it is the things to do... the cases enumerated are possible causes for a crash when deleting a pointer X|


                    TOXCCT >>> GEII power

                    [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

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                    • S see me

                      In my case the above mentioned 4 cases will not be satisfied. Actual reason is any other.:-> And also as per ur comments int * p = NULL; delete p; how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.:confused: yours faithfully ajeeshcv

                      C Offline
                      C Offline
                      Cedric Moonen
                      wrote on last edited by
                      #14

                      Ajeesh c v wrote:

                      how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.

                      That's probably your problem. When you do this:

                      int* pTest;
                      if (pTest)
                      delete pTest;

                      You will have an excpetion because you try to delete memory that is unitianalized (you can only delete memory that has been allocated with new). So, to be sure not to delete this 'unexistant' memory, assign NULL to the pointer. This is safe.


                      Cédric Moonen Software developer
                      Charting control

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                      • T toxcct

                        Ajeesh c v wrote:

                        exception is occuring.

                        DAMNNNNN !!! WHICHHHH ????? if you don't provide some descriptions of your error case, how can one help you ?? :~ :mad:


                        TOXCCT >>> GEII power

                        [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

                        S Offline
                        S Offline
                        see me
                        wrote on last edited by
                        #15

                        ok... I think the problem is occuring due to this reason. am initializing the pointer from thread...adn try to delete it from another thread.. if there is any chance of occuring exception???? Please help me... yours faithfully ajeeshcv

                        T V J 3 Replies Last reply
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                        • S see me

                          In my case the above mentioned 4 cases will not be satisfied. Actual reason is any other.:-> And also as per ur comments int * p = NULL; delete p; how the datas will be deleted from the location which is pointed by p initialy. since u r saying to delete the pointer after asigning the pointer to null.:confused: yours faithfully ajeeshcv

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                          V Offline
                          Viorel
                          wrote on last edited by
                          #16

                          According to documentation (http://msdn2.microsoft.com/en-us/library/h6227113.aspx[^]), “You can [...] use delete on a pointer with the value 0”. Therefore instead of

                          if( p != NULL )
                          {
                              delete p;
                              p = NULL;
                          }
                          

                          you can use

                          delete p;
                          p = NULL;
                          

                          However, this does not belong to original topic. I think you should put a breakpoint at the line where your block of memory is allocated and the pointer is assigned. Then investigate the pointer’s value and the content of the memory block. Then stop on the line where the pointer is deleted. Check if the pointer contains right address value. Try to use step-be-step execution during deletion. Perhaps the pointer points to an object having destructor, and the problem is within this function.

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                          • S see me

                            ok... I think the problem is occuring due to this reason. am initializing the pointer from thread...adn try to delete it from another thread.. if there is any chance of occuring exception???? Please help me... yours faithfully ajeeshcv

                            T Offline
                            T Offline
                            toxcct
                            wrote on last edited by
                            #17

                            as far as you don't answer my questions, i don't help you furthermore. :zzz:


                            TOXCCT >>> GEII power

                            [VisualCalc 3.0  updated ][Flags Beginner's Guide  new! ]

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                            • C Cedric Moonen

                              That's a very clear description of the problem :~ The solution is: you did something wrong.


                              Cédric Moonen Software developer
                              Charting control

                              S Offline
                              S Offline
                              see me
                              wrote on last edited by
                              #18

                              Thats a very precious information for me. Thank you.. yours faithfully ajeeshcv

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                              • S see me

                                ok... I think the problem is occuring due to this reason. am initializing the pointer from thread...adn try to delete it from another thread.. if there is any chance of occuring exception???? Please help me... yours faithfully ajeeshcv

                                V Offline
                                V Offline
                                Viorel
                                wrote on last edited by
                                #19

                                I think this causes problems if your project’s configuration does not allow multi-threading. You should open the project’s properties dialog and be sure that the C/C++ --> Code Generation --> Runtime Library option contains a right value related to multi-threading. Then rebuild the application.

                                S 1 Reply Last reply
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                                • H Hamid Taebi

                                  Can you show how to use pointer and how to declare pointer_**


                                  **_

                                  whitesky


                                  S Offline
                                  S Offline
                                  see me
                                  wrote on last edited by
                                  #20

                                  The pointer is of a dialog. Initialization: CMyDialog* pMyDialog; pMyDialog = new CMyDialog; pMyDialog->EndDialog(0); if(pMyDialog) { delete pMyDialog; pMyDialog = 0; } yours faithfully ajeeshcv

                                  H 1 Reply Last reply
                                  0
                                  • V Viorel

                                    I think this causes problems if your project’s configuration does not allow multi-threading. You should open the project’s properties dialog and be sure that the C/C++ --> Code Generation --> Runtime Library option contains a right value related to multi-threading. Then rebuild the application.

                                    S Offline
                                    S Offline
                                    see me
                                    wrote on last edited by
                                    #21

                                    Thank you... I don't know it will work or not. Let me check. yours faithfully ajeeshcv

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                                    • S see me

                                      The pointer is of a dialog. Initialization: CMyDialog* pMyDialog; pMyDialog = new CMyDialog; pMyDialog->EndDialog(0); if(pMyDialog) { delete pMyDialog; pMyDialog = 0; } yours faithfully ajeeshcv

                                      H Offline
                                      H Offline
                                      Hamid Taebi
                                      wrote on last edited by
                                      #22

                                      im not sure your problem is this but how to create dialog? and if you run your code i think you get a error in pMyDialog->EndDialog(0); now try this and send me if you have a error CMyDialog* pMyDialog; pMyDialog = new CMyDialog; pMyDialog->Create(IDD_TEST);//id from dialog pMyDialog->EndDialog(0); delete pMyDialog ; pMyDialog = 0;_**


                                      **_

                                      whitesky


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                                      0
                                      • S see me

                                        ok... I think the problem is occuring due to this reason. am initializing the pointer from thread...adn try to delete it from another thread.. if there is any chance of occuring exception???? Please help me... yours faithfully ajeeshcv

                                        J Offline
                                        J Offline
                                        jhwurmbach
                                        wrote on last edited by
                                        #23

                                        Ajeesh c v wrote:

                                        am initializing the pointer from thread...adn try to delete it from another thread

                                        May one thread still be accessing the memory you just deleted? Maybe using smart-pointers (like those from boost.org)[^]can help you? Or at least an object which can delete itself via a member function?


                                        "We trained hard, but it seemed that every time we were beginning to form up into teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by reorganising: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralisation." -- Caius Petronius, Roman Consul, 66 A.D.

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