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array values

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  • P Pryabu

    Hi, In the following code,i have assigned a value "test" to c variable. I have assigned the variable c to sz123. If i copied another value to c,the already assigend value in sz123[0] is getting overide. Can anyone please help me how to avoid this one? LPSTR sz123[10]; char c[20] = "test"; sz123[0] = (LPSTR)c; strcpy(c,"123"); thanks,

    A Offline
    A Offline
    Aescleal
    wrote on last edited by
    #4

    Remember you're not really copying values around, you're copying pointers. So when you do:

    sz123[ 0 ] = c;

    You're just creating an alias to the block of memory that contains "hello." I'd suggest (unless you're stuck programming in C) to avoid using character arrays, character pointers and C style strings and just use C++ strings - then when you copy them around you're actually copying values and not aliases. Cheers, Ash

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    • P Pryabu

      Hi, In the following code,i have assigned a value "test" to c variable. I have assigned the variable c to sz123. If i copied another value to c,the already assigend value in sz123[0] is getting overide. Can anyone please help me how to avoid this one? LPSTR sz123[10]; char c[20] = "test"; sz123[0] = (LPSTR)c; strcpy(c,"123"); thanks,

      CPalliniC Offline
      CPalliniC Offline
      CPallini
      wrote on last edited by
      #5

      sz123[0] = _strdup(c);
      //...
      free(sz123[0]);

      :)

      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]

      In testa che avete, signor di Ceprano?

      P 1 Reply Last reply
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      • CPalliniC CPallini

        sz123[0] = _strdup(c);
        //...
        free(sz123[0]);

        :)

        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]

        P Offline
        P Offline
        Pryabu
        wrote on last edited by
        #6

        Is it possible to use the globally declared LPSTR variable in other class by using extern function?

        CPalliniC 1 Reply Last reply
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        • P Pryabu

          Is it possible to use the globally declared LPSTR variable in other class by using extern function?

          CPalliniC Offline
          CPalliniC Offline
          CPallini
          wrote on last edited by
          #7

          Karthika85 wrote:

          Is it possible to use the globally declared LPSTR variable in other class by using extern function?

          You're mixing a bit different domains here. If the variable is global then you may use it everywhere (don't forget to call free when you no longer need the string). :)

          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]

          In testa che avete, signor di Ceprano?

          P 2 Replies Last reply
          0
          • CPalliniC CPallini

            Karthika85 wrote:

            Is it possible to use the globally declared LPSTR variable in other class by using extern function?

            You're mixing a bit different domains here. If the variable is global then you may use it everywhere (don't forget to call free when you no longer need the string). :)

            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]

            P Offline
            P Offline
            Pryabu
            wrote on last edited by
            #8

            No,I am not able to use the globally declared sz123[0] variable in another class: In class1: LPSTR sz123[10]; char c[20] = "test"; sz123[0] = (LPSTR)malloc(sizeof(c[0]) * (strlen(c) + 1)); strcpy(sz123[0], c); In class2: extern LPSTR sz123[10]; char ch1[20]; strcpy(ch1,sz123[0]); It is showing the following error "error LNK2001: unresolved external symbol "char * * sz123":

            CPalliniC L 2 Replies Last reply
            0
            • CPalliniC CPallini

              Karthika85 wrote:

              Is it possible to use the globally declared LPSTR variable in other class by using extern function?

              You're mixing a bit different domains here. If the variable is global then you may use it everywhere (don't forget to call free when you no longer need the string). :)

              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]

              P Offline
              P Offline
              Pryabu
              wrote on last edited by
              #9

              Got it.I should not use static keyword to use in other cpp files

              CPalliniC 1 Reply Last reply
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              • P Pryabu

                No,I am not able to use the globally declared sz123[0] variable in another class: In class1: LPSTR sz123[10]; char c[20] = "test"; sz123[0] = (LPSTR)malloc(sizeof(c[0]) * (strlen(c) + 1)); strcpy(sz123[0], c); In class2: extern LPSTR sz123[10]; char ch1[20]; strcpy(ch1,sz123[0]); It is showing the following error "error LNK2001: unresolved external symbol "char * * sz123":

                CPalliniC Offline
                CPalliniC Offline
                CPallini
                wrote on last edited by
                #10

                You must be precise. A global variable cannot be declared inside a class (it wouldn't be global). So what do you intend to do? Do you want to use a global variable? Do you want to make an object's member variable available to objects of different classes? :)

                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]

                In testa che avete, signor di Ceprano?

                P 1 Reply Last reply
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                • P Pryabu

                  Got it.I should not use static keyword to use in other cpp files

                  CPalliniC Offline
                  CPalliniC Offline
                  CPallini
                  wrote on last edited by
                  #11

                  Of course. The static qualifier, for varibles declared outside classes, makes the variables themselves having file-scope. :)

                  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]

                  In testa che avete, signor di Ceprano?

                  1 Reply Last reply
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                  • CPalliniC CPallini

                    You must be precise. A global variable cannot be declared inside a class (it wouldn't be global). So what do you intend to do? Do you want to use a global variable? Do you want to make an object's member variable available to objects of different classes? :)

                    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]

                    P Offline
                    P Offline
                    Pryabu
                    wrote on last edited by
                    #12

                    I decalred a global variable array not class variable in one class and i want to use that gloabl variable in another class.

                    CPalliniC 1 Reply Last reply
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                    • P Pryabu

                      I decalred a global variable array not class variable in one class and i want to use that gloabl variable in another class.

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

                      And what's your problem? For instance:

                      // global.cpp
                      int global_counter=0;

                      and

                      // source.cpp
                      extern int global_counter;

                      void show_counter()
                      {
                      cout << global_counter << endl;
                      }

                      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]

                      In testa che avete, signor di Ceprano?

                      P 1 Reply Last reply
                      0
                      • CPalliniC CPallini

                        And what's your problem? For instance:

                        // global.cpp
                        int global_counter=0;

                        and

                        // source.cpp
                        extern int global_counter;

                        void show_counter()
                        {
                        cout << global_counter << endl;
                        }

                        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]

                        P Offline
                        P Offline
                        Pryabu
                        wrote on last edited by
                        #14

                        previously i used static keyword. so,i got that error. now i removed the keyword static.

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                        • P Pryabu

                          No,I am not able to use the globally declared sz123[0] variable in another class: In class1: LPSTR sz123[10]; char c[20] = "test"; sz123[0] = (LPSTR)malloc(sizeof(c[0]) * (strlen(c) + 1)); strcpy(sz123[0], c); In class2: extern LPSTR sz123[10]; char ch1[20]; strcpy(ch1,sz123[0]); It is showing the following error "error LNK2001: unresolved external symbol "char * * sz123":

                          L Offline
                          L Offline
                          Lost User
                          wrote on last edited by
                          #15

                          You need to declare it extern in all modules, and initialize it in only one.

                          It's time for a new signature.

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