Where to define derived class consructors ?

I thought they, as for general member functions can be defined either inside the class as an inline or in a .cpp file. But I'm totally confused by the following error I'm getting.

What works:

Code:

#ifndef KEYWORD
#define KEYWORD
#include "token.h"
class Keyword : public token
{
public:
    Keyword(std::string input):token(input){/*....*/};
};

#endif

What doesn't work :
.h

Code:

#ifndef KEYWORD
#define KEYWORD
#include "token.h"
class Keyword : public token
{
public:
    Keyword(std::string input):token(input);
};

#endif

.cpp

Code:

#include "Keyword.h"
Keyword::Keyword(std::string input):token(input)
{
    
}

Error:

Originally Posted by g++-4.6

Code:

$make
g++ Keyword.cpp -c -g -std=c++0x -o keyword.o
In file included from Keyword.cpp:1:0:
Keyword.h: In constructor ‘Keyword::Keyword(std::string)’:
Keyword.h:7:43: error: expected ‘{’ at end of input
Keyword.cpp: At global scope:
Keyword.cpp:2:1: error: redefinition of ‘Keyword::Keyword(std::string)’
Keyword.h:7:5: error: ‘Keyword::Keyword(std::string)’ previously defined here
make: *** [keyword.o] Error 1

What am I missing ?

When you use the constructor initialisation list that doesn't mean you can forego having a function body. You still need empty curly braces to give the constructor a body.
That said, it appears that your problem is that you're trying to use the initialisation list in the declaration in the header AND in the cpp file, you can't do that.

Originally Posted by iMalc

When you use the constructor initialisation list that doesn't mean you can forego having a function body.
You still need empty curly braces to give the constructor a body.

I gave the body in the .cpp file, but the compiler doesn't seem to accept it.

Originally Posted by iMalc

When you use the constructor initialisation list that doesn't mean you can forego having a function body. You still need empty curly braces to give the constructor a body.
That said, it appears that your problem is that you're trying to use the initialisation list in the declaration in the header AND in the cpp file, you can't do that.

O..got it.
That only has to be in the cpp file.
No errors now.

Originally Posted by manasij7479

O..got it.
That only has to be in the cpp file.
No errors now.

You missed iMalc's point.

The initialiser list is part of the constructor definition, as is the "body" of the constructor. The initialiser list and body of the constructor have to be together. That may be either in the header file or the separate source file. Not spread between the two. Not duplicated between the two.

Originally Posted by grumpy

You missed iMalc's point.

The initialiser list is part of the constructor definition, as is the "body" of the constructor. The initialiser list and body of the constructor have to be together. That may be either in the header file or the separate source file. Not spread between the two. Not duplicated between the two.

Yes.. I did exactly that.
The header has:
Keyword(std::string input);

and the source has:

Code:

Keyword::Keyword(std::string input):token(input)
{
    /*...*/
}