This C program implements a snake game using graphics. It initializes a linked list to represent the snake and randomly generates food on the screen. It uses functions to check for collisions with food/body, move the snake according to key presses, and draw the snake/food each frame. The main game loop runs continuously, checking for input, calling functions to update the snake's position and check for collisions, drawing the updated scene, and exiting if the snake collides with itself or the edge of the screen.

1. #include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <ctype.h>
#include <graphics.h>
#include <process.h>
#include <dos.h>
void create(char);
void check();
void out();
char prevKey = 'd', pre = 'd', getKey = 'a';
struct node {
char ch;
int x1, y1, len, flag;
struct node *next;
};
struct node *start, *t, *temp, *temp2;
int flagOut, foodx, foody, max = 100, score = 0;
void main() {
int gd = DETECT, gm = 0, i,j;
flagOut = 0;
foodx = rand() % 620;
foody = rand() % 460;
initgraph(&gd, &gm, "c:turboc3bgi"); //according to your compiler
change the url.
start = (struct node *) malloc(sizeof (struct node));
start->next = NULL;
start->x1 = 150;
start->y1 = 200;
start->ch = 'd';
start->len = max;
start->flag = 1;
while (1) {
clrscr();
if (kbhit()) {
getKey = getch();
if (prevKey != getKey && getKey == 'w' || getKey == 'a' || getKey == 's'
|| getKey == 'd') {
if (prevKey == 'w' && getKey != 's' || prevKey == 's' && getKey != 'w'
|| prevKey == 'a' && getKey != 'd' || prevKey == 'd' && getKey != 'a') {
create(getKey);
prevKey = getKey;
}
}
}
for(i=-1;i<=1;i++)
{
for(j=-1;j<=1;j++)
{
putpixel(foodx+i, foody+j, 4);
}
}
check();
out();
t = start;
do {
if (t->ch == 'd') {
setcolor(4);
line(t->x1, t->y1, t->x1 - t->len, t->y1);
if (t->flag)
t->x1++;
if (t->x1 >= 640)
flagOut = 1;

2. }
if (t->ch == 'w') {
setcolor(4);
line(t->x1, t->y1, t->x1, t->y1 + t->len);
if (t->flag)
t->y1--;
if (t->y1 <= 0)
flagOut = 1;
}
if (t->ch == 'a') {
setcolor(4);
line(t->x1, t->y1, t->x1 + t->len, t->y1);
if (t->flag)
t->x1--;
if (t->x1 <= 0)
flagOut = 1;
}
if (t->ch == 's') {
setcolor(4);
line(t->x1, t->y1, t->x1, t->y1 - t->len);
if (t->flag)
t->y1++;
if (t->y1 >= 480)
flagOut = 1;
}
if (flagOut == 1) {
printf("Game OvernScore=%d", score);
delay(2000);
exit(1);
}
t = t->next;
} while (t);
delay(20);
}//while close
}
void create(char v) {
t = temp = start;
while (t) {
t->flag = 0;
temp = t;
t = t->next;
}
temp2 = (struct node *) malloc(sizeof (struct node));
temp->next = temp2;
temp2->next = NULL;
temp2->flag = 1;
temp2->x1 = temp->x1;
temp2->y1 = temp->y1;
temp2->ch = v;
temp2->len = -1;
}
void check() {
t = start;
if (t->next != NULL)
t->len--;
if (t->len <= 0) {
start = t->next;
free(t);
}
t = start;
do {

3. temp = t;
t = t->next;
} while (t);
if (temp->len < max)
temp->len++;
if (temp->x1 > foodx - 2 && temp->x1 < foodx + 2 && temp->y1 > foody - 2 &&
temp->y1 < foody + 2) {
max = max + max / 10;
foodx = rand() % 620;
foody = rand() % 460;
score = score + score / 10 + 10;
}
}
void out() {
t = temp2 = start;
while (t) {
temp = temp2;
temp2 = t;
t = t->next;
}
t = start;
while (t->next) {
if (temp2->ch == 'w' && t->ch != 's' && t->ch != 'w' || temp2->ch == 'a'
&& t->ch != 'd' && t->ch != 'a' || temp2->ch == 's' && t->ch != 'w' && t->ch !=
's' || temp2->ch == 'd' && t->ch != 'a' && t->ch != 'd') {
if (temp2->x1 == t->x1) {
if (t->ch == 'w') {
if (temp2->y1 >= t->y1 && temp2->y1 <= (t->y1 + t->len))
flagOut = 1;
}
if (t->ch == 's') {
if (temp2->y1 <= t->y1 && temp2->y1 >= (t->y1 - t->len))
flagOut = 1;
}
}
if (temp2->y1 == t->y1) {
if (t->ch == 'a') {
if (temp2->x1 >= t->x1 && temp2->x1 <= (t->x1 + t->len))
flagOut = 1;
}
if (t->ch == 'd') {
if (temp2->x1 <= t->x1 && temp2->x1 >= (t->x1 - t->len))
flagOut = 1;
}
}
}
if (temp2->y1 == t->y1 && temp2->x1 == t->x1)
flagOut = 0;
t = t->next;
}
}