Structure trouble...

This is a discussion on Structure trouble... within the C++ Programming forums, part of the General Programming Boards category; OK, lets see I am trying to use a ONE structure with multiple .cpp's (which I got to work just ...

  1. #1
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    Structure trouble...

    OK, lets see I am trying to use a ONE structure with multiple .cpp's (which I got to work just not the right way). I initialized my structure in my header file. I trying to find a way to save a value in a int or string from the structure and then be able to output the value of the struct variable in another .cpp... I search for about 2 hours on google and the boards themselves ( Im not to good at searching for stuff )... I did end up figuring out how to have 2 different values with the same name but not a way to have one with same name over the span of multiple .cpp's. any help is greatly appreciated (BELOW is a small sample program I made to try this ( it doesnt work the way I want tho ))

    This is my header
    Code:
    #include <iostream>
    #include <windows.h>
    #include <fstream>
    
    using namespace std;
    
    void menu();
    void load();
    void newg();
    int main();
    
    struct test {
    	int tst;
    };
    test tet;
    This is one .cpp
    Code:
    #include "all.h"
    
    int main()
    {
    	cout << "choose a value for tst" << endl;
    	cin >> tet.tst;
    	cin.get();
    	menu();
    }
    This is my other .cpp
    Code:
    #include "all.h"
    
    void menu()
    {
    	cout << "tst Value you chose" << tet.tst << endl;
    	cin.get();
    }
    and this is the error that I get
    Code:
    .objs\main.o:main.cpp:(.bss+0x0): multiple definition of `tet'
    Thanks again for any help you provide

  2. #2
    Registered User whiteflags's Avatar
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    You need to use inclusion guards. Google it.

  3. #3
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    The include guards didnt help me any.... any other ideas? ( I am searching google at the moment for possible solutions but I would be eternally grateful for your support)

  4. #4
    C++ Witch laserlight's Avatar
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    int main();
    The global main function shall not be used within a program, so there is really no need for you to have a prototype for it.

    The include guards didnt help me any.... any other ideas?
    The include guards should work. However, a redesign to not use a global test object is in order. Have tet created in main(), then pass it to menu(). Do not declare it in your header. If not, you have one tet used in your main() function and another used in menu(). You could declare it as extern... but why bother with a global test object in the first place?
    Last edited by laserlight; 06-25-2006 at 12:18 AM.
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  5. #5
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    How do you declare a struct int a extern?

  6. #6
    and the hat of wrongness Salem's Avatar
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    > test tet;
    This is the thing you're creating multiple instances of - it's a definition (of storage), not a declaration.
    It's what the error message is telling you.

    Move this single line to just ONE of the cpp files (probably main.cpp).
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  7. #7
    C++ Witch laserlight's Avatar
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    How do you declare a struct int a extern?
    A struct isnt an int.
    You would probably have an:
    Code:
    extern test tet;
    in your header file, but a better way is a redesign:

    the all.h header file:
    Code:
    #ifndef ALL_H
    #define ALL_H
    
    #include <iostream>
    #include <windows.h>
    #include <fstream>
    
    struct test {
    	int tst;
    };
    
    void menu(const test& tet);
    void load();
    void newg();
    
    #endif
    the file with the global main() function:
    Code:
    #include "all.h"
    
    int main()
    {
    	test tet;
    	cout << "choose a value for tst" << endl;
    	cin >> tet.tst;
    	cin.get();
    	menu(tet);
    }
    the file with the implementation of the menu() function:
    Code:
    #include "all.h"
    
    void menu(const test& tet)
    {
    	cout << "tst Value you chose" << tet.tst << endl;
    	cin.get();
    }
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  8. #8
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    oh thanks alot, so basicly I just had a design problem. you a life save thanks ( and I wasnt calling the struct and int I was talking about the int inside the struct just had bad wording)
    thanks again

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