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[QUOTE="Giovanni Gherdovich, post: 3614720"]
Hello,

As you will see from the following code snippets,
I'm trying to declare a function object in an header
file and implement it in a (different) source file, but my compiler
complains (he cannot find the implementation I provided,
apparently).
(the -c option tells the compiler to don't try to link,
just compile).

$ g++ -c addition.cpp
$ g++ -c program.cpp
program.cpp: In function `int main()':
program.cpp:5: error: no matching function for call to
`addition::addition(int, int)'
addition.h:2: note: candidates are: addition::addition()
addition.h:2: note:                 addition::addition(const
addition&)

here is the code:

// ------- this is the file addition.h
struct addition
{
  int operator()(const int x, const int y) const;
};
// ------- end of the file addition.h

// ------- this is the file addition.cpp
#include "addition.h"

int addition::operator()(const int x, const int y) const
{
  return x + y;
}
// ------- end of the file addition.cpp

// ------- this is the file program.cpp
#include "addition.h"

int main()
{
  double a = addition(1,2);
}
// ------- end of the file program.cpp

Surely I'm missing something really obvious, but what?

Regards,
Giovanni Gh.
[/QUOTE]

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