compiling different cpp files on bloodshed developer on a windows platform

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January 30th, 2004, 09:19 AM

seamus2

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compiling different cpp files on bloodshed developer on a windows platform

I have a question.

It is my understanding that makefiles can be used to link different source files together. This could be useful as it can make classes and functions that refer to them more portable. However I am unclear of how to do this.

Here is an example piece of code the source file containing my main is:

Code:

#include <iostream>

#include "test.h"


using namespace std;

int main()
{
    test t(4.0);
    cout << square(t) << '\n';

}

The header looks like this:

Code:

#ifndef TEST_H
#define TEST_H
class test
{
      private:
      double a_number;

      public:
      test()
      {
            a_number = 0;
      }
      test(double a)
      {
             a_number = a;
      }
      double geta()
      {
             return a_number;
      }
};

double square (test &);
#endif TEST_H

and the source file containing the 'square function' looks like this:

Code:

#include "test.h"

double square (test a)
{
     return a.geta() * a.geta();
}

I automatically generate a makefile with bloodshed devC++ but when I build I still get an error message saying that the main contains an undefined reference to 'square(double &)' .

Thanks for any explanation!

January 30th, 2004, 09:36 AM

dwise1_aol

Contributing User

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Posts: 6,252

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Function overloading just bit you there.

In C++, you can have several functions all with the exact same name but with different data types in the argument list. It's the different argument lists that makes each same-named function distinquishable from each other and allows the compiler to figure out which one you're calling. There's even a special term, "name mangling", that describes how the compiler appends the argument-list data types to the function name for the linker.

In test.h, you provide this function prototype:
double square (test &);
Yet in the other source file where you think that you're implementing that function, the function's header looks like this:
double square (test a)

You changed the argument-list data types, so it's a completely different function than you had prototyped in the header file. The linker error of "undefined reference to 'square(double &)'" is righteous because you never did implement a "square" function with a reference arguement (though I'm not sure why it's "double &" and not "test &").

You probably did intend the function's argument to be a reference, so just add the & and I think it should work.

January 30th, 2004, 09:57 AM

seamus2

Junior Member

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Thank you for your clarification. Can't believe that that was all that was wrong!

compiling different cpp files on bloodshed developer on a windows platform

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