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memory leak in the code?

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performancequestion
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  • E Eytukan

    huh Hamid! :| it's simply because he should have put it like:

    int* a;
    int* b;

    try { a= new int[N]; b= new int[M]; } catch (bad_alloc&) { cout <<"Error allocating memory!"; } wake up! :)


    OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus Best wishes to Rexx[^]

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    Hamid Taebi
    wrote on last edited by
    #10

    Yeah it was a quick sample. ;)

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    • E Eytukan

      huh Hamid! :| it's simply because he should have put it like:

      int* a;
      int* b;

      try { a= new int[N]; b= new int[M]; } catch (bad_alloc&) { cout <<"Error allocating memory!"; } wake up! :)


      OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus Best wishes to Rexx[^]

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      pierre_ribery
      wrote on last edited by
      #11

      Not like that, see my earlier post. Always initialize pointers!! In this case set them to NULL(0). int* a = NULL; int* b = NULL;

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      • P pierre_ribery

        Not like that, see my earlier post. Always initialize pointers!! In this case set them to NULL(0). int* a = NULL; int* b = NULL;

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        Eytukan
        wrote on last edited by
        #12

        Who said I didn't do it? I'm a c++ programmer. class myclass { int* a; int* b; myclass() { a= NULL; b= NULL; } } ;P


        OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus Best wishes to Rexx[^]

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        • E Eytukan

          But I suggest he should do something like this : if(pMyStuff!=NULL) { delete pMyStuff; } :cool:


          OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus Best wishes to Rexx[^]

          CPalliniC Offline
          CPalliniC Offline
          CPallini
          wrote on last edited by
          #13

          And you are right! :-D

          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
          [my articles]

          In testa che avete, signor di Ceprano?

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          • E Eytukan

            Who said I didn't do it? I'm a c++ programmer. class myclass { int* a; int* b; myclass() { a= NULL; b= NULL; } } ;P


            OK,. what country just started work for the day ? The ASP.NET forum is flooded with retarded questions. -Christian Graus Best wishes to Rexx[^]

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            pierre_ribery
            wrote on last edited by
            #14

            Your code said it. Anyway, I think it is pretty important to show it in the code as well.

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            • P pierre_ribery

              In a case like this you should initialize both a and b to 0 before the try clause. You cannot delete a or b at this stage, I assume you will need to use them later, or what was the purpose of allocating them? int* a = NULL; int* b = NULL; try { a = new int [N]; b = new int [M]; } catch (bad_alloc) { // Tell the user if a or b failed... } // Do some stuff on a or b // Now delete if they are allocated if(a) delete a[]; if (b) delete b[]; Thanks!

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              George_George
              wrote on last edited by
              #15

              Thanks pierre_ribery, I want to confirm with you that your point is we need to delete a or b if they are successful allocated, even if bad_alloc happens (may be caused by other statements), right? regards, George

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              • H Hamid Taebi

                Why you didnt use like this code try { int * a= new int[N]; int * b= new int[M]; } catch (bad_alloc&) { cout <<"Error allocating memory!"; }

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                George_George
                wrote on last edited by
                #16

                Hi Hamid, I am confused. My question is about whether we need to delete a or b if bad_alloc happens, does your reply has anything related to my question? :-) regards, George

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                • CPalliniC CPallini

                  Yes. :)

                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                  [my articles]

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                  George_George
                  wrote on last edited by
                  #17

                  Thanks for your confirmation, CPallini! regards, George

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                  • G George_George

                    Hi Hamid, I am confused. My question is about whether we need to delete a or b if bad_alloc happens, does your reply has anything related to my question? :-) regards, George

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                    Hamid Taebi
                    wrote on last edited by
                    #18

                    My reply was for check does it with success or no (and my suggestion is when you want to allocate or convert use of try/catch block) and when you got error means that it doesnt allocate any thing to variable.

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                    • G George_George

                      Thanks pierre_ribery, I want to confirm with you that your point is we need to delete a or b if they are successful allocated, even if bad_alloc happens (may be caused by other statements), right? regards, George

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                      pierre_ribery
                      wrote on last edited by
                      #19

                      Yes that was exactly my point! If you have allocated memory, then you have to delete it. Therefore it is vital to initialize your pointers to 0 before using them. Cheers, Pierre

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                      • H Hamid Taebi

                        My reply was for check does it with success or no (and my suggestion is when you want to allocate or convert use of try/catch block) and when you got error means that it doesnt allocate any thing to variable.

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                        George_George
                        wrote on last edited by
                        #20

                        Thanks Hamid, I have developed a couple of samples, which specific case do you think I need to check? regards, George

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                        • P pierre_ribery

                          Yes that was exactly my point! If you have allocated memory, then you have to delete it. Therefore it is vital to initialize your pointers to 0 before using them. Cheers, Pierre

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                          George_George
                          wrote on last edited by
                          #21

                          Thanks for your advice, Pierre! regards, George

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                          • G George_George

                            Thanks Hamid, I have developed a couple of samples, which specific case do you think I need to check? regards, George

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                            Hamid Taebi
                            wrote on last edited by
                            #22

                            If you check each block of your program(for exmaple is hwnd valid,etc) you can almost(not always) sure that you didnt get an exception when you run your program

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                            • H Hamid Taebi

                              If you check each block of your program(for exmaple is hwnd valid,etc) you can almost(not always) sure that you didnt get an exception when you run your program

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                              George_George
                              wrote on last edited by
                              #23

                              Hi Hamid, How could I check manually which block is exception safe or not? There are too many runtime errors, like out of memory or input invalid values to new which will cause bad_alloc. :-) regards, George

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                              • G George_George

                                Hi Hamid, How could I check manually which block is exception safe or not? There are too many runtime errors, like out of memory or input invalid values to new which will cause bad_alloc. :-) regards, George

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                                Hamid Taebi
                                wrote on last edited by
                                #24

                                Well its simple you know some actions will be problem and you can anticipate them a short list like: (1) When you want to read a file or write a file:1-does file exist 2-does this file open with other programs 3- can you write to a file on the cd or no,does file on the floppy drive and does it write-protected or no (2) Database do you have access to database (3) when you need to a handle to a window does return value valid or its null (4) Picture does file a image file or no what was return value (5) when you want to read of internet do you have any connection to internet (6) do you have a valid pointer or its null (7) Dynamic memory,does it valid (8).... ------------------------------ After all of them you must free memory. ;)

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                                • H Hamid Taebi

                                  Well its simple you know some actions will be problem and you can anticipate them a short list like: (1) When you want to read a file or write a file:1-does file exist 2-does this file open with other programs 3- can you write to a file on the cd or no,does file on the floppy drive and does it write-protected or no (2) Database do you have access to database (3) when you need to a handle to a window does return value valid or its null (4) Picture does file a image file or no what was return value (5) when you want to read of internet do you have any connection to internet (6) do you have a valid pointer or its null (7) Dynamic memory,does it valid (8).... ------------------------------ After all of them you must free memory. ;)

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                                  George_George
                                  wrote on last edited by
                                  #25

                                  Thanks Hamid, Comprehensive samples. regards, George

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                                  • G George_George

                                    Thanks Hamid, Comprehensive samples. regards, George

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                                    Hamid Taebi
                                    wrote on last edited by
                                    #26

                                    I glad I could help to you. ;)

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                                    • H Hamid Taebi

                                      I glad I could help to you. ;)

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                                      George_George
                                      wrote on last edited by
                                      #27

                                      Thanks Hamid, Hope we can have further discussion here -- other topics -- I will find one soon. :-) regards, George

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                                      • G George_George

                                        Thanks Hamid, Hope we can have further discussion here -- other topics -- I will find one soon. :-) regards, George

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                                        Hamid Taebi
                                        wrote on last edited by
                                        #28

                                        Very good. ;P

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                                        • G George_George

                                          Thanks Hamid, Hope we can have further discussion here -- other topics -- I will find one soon. :-) regards, George

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                                          Hamid Taebi
                                          wrote on last edited by
                                          #29

                                          I remember when use of controls and other objects check memory for size of program. ;)

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