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Array Variable initialization

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  • D David Crow

    CPallini wrote:

    00401003 xor eax,eax

    Look two lines up from this one and you should find:

    rep stosd

    "Love people and use things, not love things and use people." - Unknown

    "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

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    CPallini
    wrote on last edited by
    #16

    No luck (there isn't such insruction). On the other hand, the output of this program [^] confirms my assumption. See also Sandip's post [^]. I should admit I was very surprised by such a behaviour. :)

    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.
    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
    [My articles]

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    • S SandipG

      Same output with Visual C++ 6.0, WinXP SP2 :) Surprising..:confused:

      Regards, Sandip.

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      toxcct
      wrote on last edited by
      #17

      SandipG :) wrote:

      Same output with Visual C++ 6.0

      Visual C++ is not what a decent programmer call a standard compliant compiler, Sir !

      [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

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      • C CPallini

        No luck (there isn't such insruction). On the other hand, the output of this program [^] confirms my assumption. See also Sandip's post [^]. I should admit I was very surprised by such a behaviour. :)

        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.
        This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
        [My articles]

        T Offline
        T Offline
        toxcct
        wrote on last edited by
        #18

        and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

        [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

        C D 2 Replies Last reply
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        • T toxcct

          and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

          [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

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          CPallini
          wrote on last edited by
          #19

          See my added remark here [^]. BTW my tests were of course performed both in Debug and the Release mode. ;P :)

          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.
          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
          [My articles]

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          • T toxcct

            and what about {0} instead of {7}, and in Release Mode, not in Debug Mode ?

            [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

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            David Crow
            wrote on last edited by
            #20

            toxcct wrote:

            ...and what about {0} instead of {7}...

            0 works fine.

            toxcct wrote:

            ...and in Release Mode, not in Debug Mode ?

            Same results for both 0 and 7. This is why I only do it when setting things to 0. I use memset() otherwise.

            "Love people and use things, not love things and use people." - Unknown

            "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

            C 1 Reply Last reply
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            • T toxcct

              SandipG :) wrote:

              Same output with Visual C++ 6.0

              Visual C++ is not what a decent programmer call a standard compliant compiler, Sir !

              [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

              C Offline
              C Offline
              CPallini
              wrote on last edited by
              #21

              IMHO such a discrepancy would be too gross, even for VC6. :)

              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.
              This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
              [My articles]

              T 1 Reply Last reply
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              • C CPallini

                IMHO such a discrepancy would be too gross, even for VC6. :)

                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.
                This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                [My articles]

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                T Offline
                toxcct
                wrote on last edited by
                #22

                yes, probably, but it's not *THE* compiler to test the standard ! ;) ;P

                [VisualCalc][Binary Guide][CommDialogs] | [Forums Guidelines]

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                • D David Crow

                  toxcct wrote:

                  ...and what about {0} instead of {7}...

                  0 works fine.

                  toxcct wrote:

                  ...and in Release Mode, not in Debug Mode ?

                  Same results for both 0 and 7. This is why I only do it when setting things to 0. I use memset() otherwise.

                  "Love people and use things, not love things and use people." - Unknown

                  "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                  C Offline
                  C Offline
                  CPallini
                  wrote on last edited by
                  #23

                  DavidCrow wrote:

                  0 works fine.

                  It is just a side-effect of default (int) initialization: you're actually initializing only the first array item. Try the following code:

                  #include <iostream>
                  using namespace std;

                  struct MyStruct
                  {
                  MyStruct():_i(-1), _j(0),_k(-1){ }
                  MyStruct(int a):_i(a), _j(a), _k(a){ }
                  int _i,_j,_k;
                  };

                  void main()
                  {
                  int i;
                  MyStruct a[5] = {0};
                  for (i=0; i<5; i++)
                  {
                  cout << i << ") {" << a[i]._i << ", " << a[i]._j <<", " << a[i]._k << "}" << endl;
                  }
                  }

                  DavidCrow wrote:

                  This is why I only do it when setting things to 0. I use memset() otherwise.

                  The above is a wise approach. :)

                  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.
                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                  [My articles]

                  D 1 Reply Last reply
                  0
                  • C CPallini

                    DavidCrow wrote:

                    0 works fine.

                    It is just a side-effect of default (int) initialization: you're actually initializing only the first array item. Try the following code:

                    #include <iostream>
                    using namespace std;

                    struct MyStruct
                    {
                    MyStruct():_i(-1), _j(0),_k(-1){ }
                    MyStruct(int a):_i(a), _j(a), _k(a){ }
                    int _i,_j,_k;
                    };

                    void main()
                    {
                    int i;
                    MyStruct a[5] = {0};
                    for (i=0; i<5; i++)
                    {
                    cout << i << ") {" << a[i]._i << ", " << a[i]._j <<", " << a[i]._k << "}" << endl;
                    }
                    }

                    DavidCrow wrote:

                    This is why I only do it when setting things to 0. I use memset() otherwise.

                    The above is a wise approach. :)

                    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.
                    This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                    [My articles]

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                    D Offline
                    David Crow
                    wrote on last edited by
                    #24

                    For structs, I'd use memset(). I only use 0 for POD types.

                    "Love people and use things, not love things and use people." - Unknown

                    "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                    C 1 Reply Last reply
                    0
                    • D David Crow

                      For structs, I'd use memset(). I only use 0 for POD types.

                      "Love people and use things, not love things and use people." - Unknown

                      "The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

                      C Offline
                      C Offline
                      CPallini
                      wrote on last edited by
                      #25

                      DavidCrow wrote:

                      For structs, I'd use memset(). I only use 0 for POD types.

                      That's good. :)

                      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.
                      This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                      [My articles]

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