learning c++

[vimivijay]

what is polymorphism? and what is operator overloading?
what is difference between dll and lib? and how they are differenet and when to use which one?

[dude_1967]

Polymorphism:

Polymorphism is the term used to describe the process by which different implementations of a function with the same name and the same number and the same types of input/output parameters can can be accessed for different objects. Polymorphism is achieved by overloading (re-writing) a function, either in a class hierarchy or for globally defined functions. There is the so-called compile-time polymorphism, for which the compiler can resolve the appropriate function to call at compile-time. There is also the so-called run-time polymorphism, for which the decision, which functinon to call will be made during program flow.

Do not immediately associate polymorphism with operator overloading. Operator overloading is an example of compile-time polymorphism. Existing global operations (functions) such as +, -, *, /, etc., can be re-written (overloaded) such that the compiler is able to resolve the appropriate function to call at run-time.

Run-time polymorphism arises in class hierarchies for which functions declared with the virtual modifier are overloaded in derived classes. See the code example below.

The topic of lib, dll:
A libraries (lib) is collection of existing, compiled codes which is statically linked to a program at the time of building the program. A dynamic link library (dll) is an existing collection of compiled codes which is loaded simultaneously loaded into the run-time environment of a program, providing run-time access to the compiled functions within the dll to the running program.

Chris

#include <iostream>
using namespace std;

class A
{
public:

  virtual const void print(void) const
  {
    cout << "A" << endl;
  }
};

class B : public A
{
public:

  const void print(void) const
  {
    cout << "B" << endl;
  }
};

static void do_print_obj(const A& the_object)
{
  the_object.print();
}

static void do_print_ptr(const A* p_object)
{
  // Run-time polymorphism
  p_object->print();
}

int main(int argc, char* argv[])
{
  A the_a;
  B the_b;

  do_print_obj(the_a);
  do_print_obj(the_b);

  do_print_ptr(&the_a);
  do_print_ptr(&the_b);

  return 1;
}

[dude_1967]

Get a good introductory book such as "C++ from the Ground Up", Herbert Schildt

http://www.amazon.com/exec/obidos/AS...646980-0930441

Chris.

[Paul McKenzie]

Originally posted by dude_1967
Get a good introductory book such as "C++ from the Ground Up", Herbert Schildt

http://www.amazon.com/exec/obidos/AS...646980-0930441

Chris.

Here is a review of the book you mentioned by C++ peers:

http://www.accu.org/cgi-bin/accu/rvo...file=cp001728a

Schildt may write well, but beginners who want to get things done correctly should look elsewhere. Maybe "Accelerated C++" by Koenig & Moo:

http://www.accu.org/cgi-bin/accu/rvo...&file=a002212a

Regards,

Paul McKenzie

[dude_1967]

In another post in this forum (see link below) other gurus pointed out some books which are probably much better than that one from Schildt.

The C++ language is very powerful, offering the muscle to program in a terse, condensed and efficient fashion without compromising on expressiveness.

http://www.codeguru.com/forum/showth...hreadid=199603

Thanks, gurus.

dude_1967