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memory leak in the code?

Scheduled Pinned Locked Moved C / C++ / MFC
performancequestion
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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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    Eytukan
    wrote on last edited by
    #8

    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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    • CPalliniC CPallini

      You have always to do your cleanup stuff! :)

      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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      Eytukan
      wrote on last edited by
      #9

      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[^]

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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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