Help with Borland & Linking

This is a discussion on Help with Borland & Linking within the C++ Programming forums, part of the General Programming Boards category; Hello...this is my first time posting here, so if I screw up the code tags or something.... Okay, I'm having ...

  1. #1
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    Help with Borland & Linking

    Hello...this is my first time posting here, so if I screw up the code tags or something....

    Okay, I'm having trouble getting multiple files to compile with Borland C++Builder 4.0 I followed my school textbook example, but it doesn't give compiler specific instructions. I've tried adding all the files to a project, but I get this error:

    [Linker Error] Unresolved external 'GetSum(int, int)' referenced from C:\PROGRAM FILES\BORLAND\CBUILDER4\PROJECTS\FUNCTION\FUNCTION .OBJ

    Here is the code:

    Code:
    //main.cpp
    
    #include <iostream.h>
    #include <conio.h>
    #include "test.h"
    
    int main()
    {
            int num1=5;
            int num2=5;
            int sum;
    
            sum=GetSum(num1,num2);
            
            cout << sum;
    
            getch();
            return 0;
    }
    Code:
    //getsum.cpp
    #include "test.h"
    
    int GetSum(int num1, int num2)
    	{
    	int sum;
    	sum=num1+num2;
    	return sum;
    	}
    Code:
    //test.h
    #ifndef SUM
    
    int GetSum(int num1, int num2);
    
    #define SUM
    #endif
    Is there a problem with my code, or am I not doing something to compile or link it right? If anyone has experience with C++Builder 4, I could really use your help with this. Thanks.

  2. #2
    Confused Magos's Avatar
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    The code seems fine, so the error lies in the linking. You said you added the files to a project, so I see no reason why it shouldn't work though...
    MagosX.com

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  3. #3
    xmdvp
    Guest
    you simply forgot to define SUM in your main.cpp:
    Code:
       #define SUM
    because a compile time, because the macro SUM isn't define, the function GetSum isn't compiled!!

  4. #4
    Confused Magos's Avatar
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    Originally posted by xmdvp
    you simply forgot to define SUM in your main.cpp:
    Code:
       #define SUM
    because a compile time, because the macro SUM isn't define, the function GetSum isn't compiled!!
    Nope! Notice the n in #ifndef meaning "if not defined". The function declaration is included if SUM is not defined.

    Also, the error he gets is "unresolved external" which appears if you have the declaration but not the definition. If you miss the declaration, you get an "undeclared identifier" message or something.
    MagosX.com

    Give a man a fish and you feed him for a day.
    Teach a man to fish and you feed him for a lifetime.

  5. #5
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    Does anyone else have some suggestions that I could try to get this program working? It's very hard trying to continue learning C++ when you can't have multiple file programs...I can't compile half of the examples, and my teacher never taught us anything about using C++Builder4 except making a new project and hitting the compile button.

    At this point, I'm open to any ideas or suggestions. Thank you.

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