c++을 배우고 있는데요

그래서 이번에 먼가 만들어볼려구....하는데..

이소를 가지고 좀더 개조해볼까하는데..

당장 이소스가 이해가 안되내요..잘..

이해좀 할수있게...쉽게쉽게 주석좀 달아주세요''

#include <iostream>
#include <windows.h>
#include <time.h>
#include <conio.h>

using std::cout;
using std::cin;
using std::endl;

#define HEIGHT 20
#define WIDTH 60
#define ZERO 0
#define UP 72
#define DOWN 80
#define LEFT 75
#define RIGHT 77


//**********************************화면 클레스*************************************************
class Screen {
char bk[HEIGHT][WIDTH];
int key;
public:
Screen();
void SetCh(int _ch) { key = _ch; }
int GetCh() { return key; }
void Show();
};


Screen::Screen()
{int i;
for(i=0; i<HEIGHT; i++) {
  for(int j=0; j<WIDTH; j++) {
   bk[i][j] = ' ';
  }
}
for(i=0; i<HEIGHT; i++) {
  bk[i][ZERO] = '@';
  bk[i][WIDTH-1] = '@';

}
for(i=0; i<WIDTH; i++) {
  bk[ZERO][i] = '@';
  bk[HEIGHT-1][i] = '@';
}
this->Show();
}

void Screen::Show()
{
for(int i=0; i<HEIGHT; i++) {
  for(int j=0; j<WIDTH; j++) {
   cout<<bk[i][j];
  }
  cout<<endl;
}
}

//*******************************뱀 클레스****************************************8
class Snake {
int x;
int y;
int Fx;
int Fy;
int course;
int temp;
Snake * tail;
Snake * next;
public:
Snake();
Snake(Snake * snake);

void SetX(int _x) { x = _x; }
void SetY(int _y) { y = _y; }
void SetCourse(int _course) { course = _course; }
void SetNext(Snake * _next) { next = _next; }

int GetX() { return x; }
int GetY() { return y; }
int GetCourse() { return course; }
Snake * GetNext() { return next; }

void AddX() { x++; }
void AddY() { y++; }
void SubX() { x--; }
void SubY() { y--; }

void Move(Snake * s);
void Cmp(Snake * s);
void Gotoxy(int,int);
void Food();
void Show(Snake *s);
void Del(Snake * s);

Snake * GetThis() { return this; }
Snake * GetTail() { return tail; }
};


Snake::Snake()
{
srand((unsigned int)time(NULL));
x = rand()%50+5;
y = rand()%10+5;
next = NULL;
tail = this;
Gotoxy(x,y);
cout<<"@";
Food();
}

Snake::Snake(Snake * snake)
{
course = snake->course;

switch(course) {
case UP:
  y = snake->y+1;
  x = snake->x;
  break;
case DOWN:
  y = snake->y-1;
  x = snake->x;
  break;
case LEFT:
  x = snake->x+1;
  y = snake->y;
  break;
case RIGHT:
  x = snake->x-1;
  y = snake->y;
  break;
default:
  cout<<"에러!!! 잘못된 방향값이 들어 왔습니다";
  exit(-1);
}

tail = GetThis();
next = NULL;
}

void Snake::Del(Snake * h)
{
Snake * p;
while(h->next != NULL) {
  p = h;
  delete p;
  h = h->next;
}
delete h;
}

void Snake::Food()
{
srand((unsigned int)time(NULL));
Fx = rand()%57+1;
Fy = rand()%18+1;
Gotoxy(Fx,Fy);
cout<<"#";
}

void Snake::Gotoxy(int x, int y){ // 좌표값 얻기
     COORD Cur;
     Cur.X=x;
     Cur.Y=y;
     SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE),Cur);
}

void Snake::Cmp(Snake * s)
{
switch(s->course) {
case UP:
  s->SetY(s->y-1);
  s->SetX(s->x);
  break;
case DOWN:
  s->SetY(s->y+1);
  s->SetX(s->x);
  break;
case LEFT:
  s->SetX(s->x-1);
  s->SetY(s->y);
  break;
case RIGHT:
  s->SetX(s->x+1);
  s->SetY(s->y);
  break;
default:
  cout<<"에러!!! 잘못된 방향값이 들어 왔습니다";
  exit(-1);
}

}

void Snake::Show(Snake * p)
{
while(p->next != NULL) {
  Gotoxy(p->x, p->y);
  cout<<'@';
  p = p->next;
}
Gotoxy(p->x, p->y);
cout<<'@';
}

void Snake::Move(Snake * s) {
Snake * h1 = s;
Snake * h2 = s;
int temp2;

if(x==0 || y==0 || x==WIDTH-1 || y==HEIGHT-1) {
  Gotoxy(0,20);
  cout<<"벽에 부닦쳤습니다."<<endl;
  cout<<"Game Over!!"<<endl;
  exit(0);
}

if(Fx == x && Fy == y) {
  Food();
  Snake * p = new Snake(tail); //추가 생성
  tail->next = p;
  tail = p;
}

h1->temp = s->course;
while(s->next != NULL) {
  Cmp(s);
  if(h1->temp != s->course) {
   temp2 = s->course;
   s->course = h1->temp;
   h1->temp = temp2;
  }
  s = s->next;
}

Cmp(s);  //NULL인 객체 처리

if(h2->next == NULL) {
  ;
} else {
  h2 = h2->next;
  while(h2->next != NULL) {
   if(h1->x == h2->x && h1->y == h2->y) {
    Gotoxy(0,20);
    cout<<"몸통 박치기 하셨습니다."<<endl;
    cout<<"Game Over!!"<<endl;
    exit(0);
   }
   h2 = h2->next;
  }
}

if(h1->temp != s->course) {
  temp2 = s->course;
  s->course = h1->temp;
  h1->temp = temp2;
}

Show(h1);
Sleep(100);
Gotoxy(tail->x, tail->y);
cout<<' ';
}
//***********************************전역변수********************************************
// **********************************메인함수********************************************
int main(void)
{
int ch=0, count=0;
int x,y;

Screen scr;
Snake * head = new Snake();

x = head->GetX();
y = head->GetY();
while(1) {
  if(_kbhit()) {
   scr.SetCh(_getch());
   if(scr.GetCh() == 224)
    scr.SetCh(_getch());
  }
  switch(scr.GetCh()) {
  case RIGHT:
   head->SetCourse(RIGHT);
   head->Move(head);
   break;
  case LEFT:
   head->SetCourse(LEFT);
   head->Move(head);
   break;
  case DOWN:
   head->SetCourse(DOWN);
   head->Move(head);
   break;
  case UP:
   head->SetCourse(UP);
   head->Move(head);
   break;
  case 'q':
   head->Gotoxy(0,20);
   cout<<"프로그램 종료"<<endl;
   return 1;
  default:
   break;
  }
  if(count<1) {
   count++;
   head->Gotoxy(x,y);
   cout<<' ';
  }
}

head->Del(head);
head->Gotoxy(0,20);
return 0;
}