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memory leak in the code?

Scheduled Pinned Locked Moved C / C++ / MFC
performancequestion
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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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                                  • H Hamid Taebi

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

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                                    George_George
                                    wrote on last edited by
                                    #30

                                    Hi Hamid, Is your comment related to my original question? My question is not talking about windows controls. :-) regards, George

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                                    • G George_George

                                      Hi Hamid, Is your comment related to my original question? My question is not talking about windows controls. :-) regards, George

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                                      Hamid Taebi
                                      wrote on last edited by
                                      #31

                                      No I think its helpful if you know. :-D

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                                      • H Hamid Taebi

                                        No I think its helpful if you know. :-D

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                                        George_George
                                        wrote on last edited by
                                        #32

                                        Hi Hamid, I am interested. What do you mean "check memory size of a program"? Could you provide some samples or links or more descriptions please? regards, George

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                                        • G George_George

                                          Hi Hamid, I am interested. What do you mean "check memory size of a program"? Could you provide some samples or links or more descriptions please? regards, George

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                                          Hamid Taebi
                                          wrote on last edited by
                                          #33

                                          My intent is when run your program monitor memory for detaily of your program.

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