cpp stu

/*

My notes in last odyssey how freelancer

 last work was nes to fix a code with
 WxWidgets, so i lost time to fix that
 code, z dont h exp in "C++",b i was haz
 to read Stroustrup's book,i ob quite stu
 to pru to ry, i vot to write this dok.

 So i ub to write code in ansi C
 b in last times, i played quite with
 C++ , so this code is demo of su thing
 that i ob about cpp.


author:Antonio aka "Cooler_"
e-mail=c00f3r[at]gmail[dot]com

-
 C like functions same to "stdio.h",
 so u can declare "stdio.h" too,b with
 out of cpp standard...
*/
#include <cstdio>

using namespace std;

class Animal {
// simple heritage ,default is "private:" so private not use heritage
 public:
// virtual modifier defines polymorphic behavior of function members
  virtual void food() = 0;
  virtual void sound() = 0;
};

class Dog : public Animal {
 public:
  void food() { std::puts("Pedigree"); }
  void sound() { std::puts("wof!"); }
};

class Cat : public Animal {
 public:
  void food() { std::puts("Purina"); }
  void sound() { std::puts("meow!"); }
};


// templates,with this u can use vars without declare each type of var,however quite util to reuse code
template <class X>
 void swap(X &a, X &b)    // tempalte function
 {
  a^=b;
  b^=a;
  a^=b;
 }


// tru this change dest 2 src
void transmute(void *dest, void *src) {
  *(void **)dest = *(void **)src;
}

// Number of elements in an array
#define sizeof_array(a) (sizeof a / sizeof a[0])

int main()
{
// first trick array size
 char word[5]="bobo";
 std::printf("array word size: %d\n", sizeof_array(word));

// second step swap with template
 int x=2,y=8;
 swap(x,y);
 std::printf("%d\n",x);

// third step , the simple transmute
  Dog *dog = new Dog();
  Cat *cat = new Cat();
  dog->food();
// function to change dog with cat
  transmute(dog,cat);
  dog->food();

/*
 gag caution!
  az u need use "new", this use heap,
  then u nes us "delete", to free memory.
  if not use cause memory leak.
*/
  delete dog,cat;

  return 0;
}