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Array Variable initialization

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  • L laksh2204

    I think you are trying to do something like this.. class A{ int TModels[3]; public: A():TModels[1](0){} }; int main(){ A a; } which is giving you above error: As per my knowledge there is no (standard) C++ way of doing this. Array initializers do not exist for classes. So prob you can do it somewhat like this: class A{ int TModels[3]; public: A(){ for(int i=0; i<3; i++) TModels[i] = 0; } }; int main(){ A a; } Hope it helps you

    T Offline
    T Offline
    T RATHA KRISHNAN
    wrote on last edited by
    #7

    Thanks. I've already corrected that.

    1 Reply Last reply
    0
    • T T RATHA KRISHNAN

      Oh! With Pleasure! First I initialized the array elements like this:

      TestAI::TestAI() //Constructor
      TModels[1](0)
      , TModels[2](0)
      , TModels[3](0)
      {

      }

      and now I change it to the following:

      TestAI::TestAI() //Constructor
      {
      TModels[1] = 0;
      TModels[2] = 0;
      TModels[3] = 0;

      }

      and the errors vanished.

      T Offline
      T Offline
      toxcct
      wrote on last edited by
      #8

      why don't you just do this :

      TModel = {0};

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

      C 1 Reply Last reply
      0
      • T toxcct

        why don't you just do this :

        TModel = {0};

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

        C Offline
        C Offline
        CPallini
        wrote on last edited by
        #9

        Because it doesn't work? For instance

        int a[50] = {0};

        Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

        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 D 2 Replies Last reply
        0
        • C CPallini

          Because it doesn't work? For instance

          int a[50] = {0};

          Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

          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
          #10

          CPallini wrote:

          Am i wrong?

          you are, or the compiler is ! the standard says that such a construction (when initializing a variable at the same time than declaration) initializes every element of the array to their default value. I'm even pretty sure Nemanja Trifunovic quoted me somewhere about that...

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

          C 1 Reply Last reply
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          • C CPallini

            Because it doesn't work? For instance

            int a[50] = {0};

            Doesn't produce the result I'm expecting (it initializes only the first array element). Am i wrong? :)

            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 Offline
            D Offline
            David Crow
            wrote on last edited by
            #11

            CPallini wrote:

            (it initializes only the first array element).

            Not according to the STOSx instructions. Of course, I only use it to initialize POD types to 0. Otherwise, I'd use memset().

            "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
            • T toxcct

              CPallini wrote:

              Am i wrong?

              you are, or the compiler is ! the standard says that such a construction (when initializing a variable at the same time than declaration) initializes every element of the array to their default value. I'm even pretty sure Nemanja Trifunovic quoted me somewhere about that...

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

              C Offline
              C Offline
              CPallini
              wrote on last edited by
              #12

              toxcct wrote:

              you are, or the compiler is !

              Maybe the latter: the program:

              #include <iostream>
              using namespace std;

              void main()
              {
              const int N = 10;
              int a[N]={7};

              for (int i=0; i<N;i++)
              {
              cout << a[i] << endl;
              }
              }

              the output:

              7
              0
              0
              0
              0
              0
              0
              0
              0
              0

              The system: Visual C++ 2008 Express Edition running on Win XP. Eventually YOU may be wrong! ;P (actually I'm quite confident you're right, but don't use it unless you really want surprises!) [added] Actually I think VS2008 cannot be so out-of-the-standard. I suppose the standard establishing that, whenever the initialization list is too short, the remaining array items are default-initialized (to 0 if integers). [/added] :)

              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]

              modified on Tuesday, September 9, 2008 11:53 AM

              S 1 Reply Last reply
              0
              • D David Crow

                CPallini wrote:

                (it initializes only the first array element).

                Not according to the STOSx instructions. Of course, I only use it to initialize POD types to 0. Otherwise, I'd use memset().

                "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
                #13

                Sorry no STOS here:

                ...
                const int N = 10;
                int a[N]={7};
                00401003 xor eax,eax
                00401005 push esi
                00401006 mov dword ptr [esp+8],7
                0040100E mov dword ptr [esp+0Ch],eax
                00401012 mov dword ptr [esp+10h],eax
                00401016 mov dword ptr [esp+14h],eax
                0040101A mov dword ptr [esp+18h],eax
                0040101E mov dword ptr [esp+1Ch],eax
                00401022 mov dword ptr [esp+20h],eax
                00401026 mov dword ptr [esp+24h],eax
                0040102A mov dword ptr [esp+28h],eax
                0040102E mov dword ptr [esp+2Ch],eax
                ...

                (Visual C++ 2008 Express Edition, Win XP). :)

                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

                  toxcct wrote:

                  you are, or the compiler is !

                  Maybe the latter: the program:

                  #include <iostream>
                  using namespace std;

                  void main()
                  {
                  const int N = 10;
                  int a[N]={7};

                  for (int i=0; i<N;i++)
                  {
                  cout << a[i] << endl;
                  }
                  }

                  the output:

                  7
                  0
                  0
                  0
                  0
                  0
                  0
                  0
                  0
                  0

                  The system: Visual C++ 2008 Express Edition running on Win XP. Eventually YOU may be wrong! ;P (actually I'm quite confident you're right, but don't use it unless you really want surprises!) [added] Actually I think VS2008 cannot be so out-of-the-standard. I suppose the standard establishing that, whenever the initialization list is too short, the remaining array items are default-initialized (to 0 if integers). [/added] :)

                  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]

                  modified on Tuesday, September 9, 2008 11:53 AM

                  S Offline
                  S Offline
                  SandipG
                  wrote on last edited by
                  #14

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

                  Regards, Sandip.

                  T 1 Reply Last reply
                  0
                  • C CPallini

                    Sorry no STOS here:

                    ...
                    const int N = 10;
                    int a[N]={7};
                    00401003 xor eax,eax
                    00401005 push esi
                    00401006 mov dword ptr [esp+8],7
                    0040100E mov dword ptr [esp+0Ch],eax
                    00401012 mov dword ptr [esp+10h],eax
                    00401016 mov dword ptr [esp+14h],eax
                    0040101A mov dword ptr [esp+18h],eax
                    0040101E mov dword ptr [esp+1Ch],eax
                    00401022 mov dword ptr [esp+20h],eax
                    00401026 mov dword ptr [esp+24h],eax
                    0040102A mov dword ptr [esp+28h],eax
                    0040102E mov dword ptr [esp+2Ch],eax
                    ...

                    (Visual C++ 2008 Express Edition, Win XP). :)

                    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 Offline
                    D Offline
                    David Crow
                    wrote on last edited by
                    #15

                    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

                    C 1 Reply Last reply
                    0
                    • 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

                      C Offline
                      C Offline
                      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]

                      T 1 Reply Last reply
                      0
                      • S SandipG

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

                        Regards, Sandip.

                        T Offline
                        T Offline
                        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]

                        C 1 Reply Last reply
                        0
                        • 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]

                            C Offline
                            C Offline
                            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]

                            1 Reply Last reply
                            0
                            • T toxcct

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

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

                              D Offline
                              D Offline
                              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
                              0
                              • 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
                                0
                                • 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]

                                  T Offline
                                  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]

                                  1 Reply Last reply
                                  0
                                  • 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]

                                      D Offline
                                      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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