redefinitions?

if you use a header file witjh your class definition try something like:

xyz.h

#ifndef __MYCLASSABC_H__
define __MYCLASSABC_H__

class ABC
{
....
};

#endif

now you should be able to include this header into as many files as you need without getting an error.

If you're referring to a base class with functions that are overridden by other classes derived from that base class, you need to make sure that each of those functions is declared virtual,

i.e.:

class mybase
{
private:
public:
  virtual int funct1(int a);
  virtual float funct2(float a);
}

class mysub1 : public mybase
{
private:
public:
  int funct1(int a, int b=4);
  float funct2(float a, float b=5);
}

class mysub2 : public mybase
{
private:
public:
  int funct1(int a);
  float funct2(float a);
}


Is that what you meant?

Great answers, all of them but can u pls tell me how does #ifndef work? what do u ahve to put after that keyword? it seems to always have a underscore somewhere in that word, how does it work? thanks

#ifndef is short for "If Not Defined".  The word after it is merely a token, or name.  All it's doing is saying "If this word has not yet been defined with a #define, then do all of the next commands until the #endif.  If it has been, skip all of the commands between here and the #endif."

You might be knowing that this is
done at the time of pre-processing
i.e. before compilation.

>> If you're referring to a base class with functions
>> that are overridden by other classes derived from
>> that base class, you need to make sure that each
>> of those functions is declared virtual,
That is not true.

It also has nothing to do with this problem.

thanks alot everyone, i get it now. sorry for the late reply.