I'm stuck doing the snake game with ncurses, I can't get the snake to move continuously

Question

i am trying to implement this snake tutorial https://www.youtube.com/watch?v=XdahrXxX5zE&list=PL3pKgZpYZLjmNpbeZrcL8pBSq3YPb-8G6&index=14, and i stuck trying to make the snake move by itself in the direction that i pressed (a,w,s,d), and i am in the part of the tutoria where the guy says that i need to reemmplaze the var with the dir variable in order to make the continuis movemento of the snake this is where my programs have odd errors, first the snake does not move continously and y already did the part in the tutorial that makes that, and when i keep press one of the keys it do start to move continuisly but it stop to answering to the keyboard

weird bugs i have also more odd bugs like that segment violation or the fack that i need to press a key to make the frog appears but this is not that bad as the first bug describe at the begiinit it does not allowme to continue the program

here is my code

#include <cctype>
#include <cstdlib>
#include <curses.h>
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
#include <stdlib.h>
#include <ncurses.h>
#include <ctime>
#include <time.h>
#include <errno.h>
#define N 20
#define M 40
int i,j,Field[N][M],x,y,gy,Head,Tail,Game,Frogs,a ,b,var,dir;
void snakeInitialization(){
  for(i=0;i<N;i++){
    for(j=0;j<M;j++){
      Field [i][j]=0;
    }
  }
  x=N/2;
  y=M/2;
  Head=5;
  Tail=1;
  gy=y;
  Game = 0;
  Frogs = 0;
  a = 0;
  b = 0;
  var = 0;
  for(i=0;i<Head;i++)
  {
    gy++;
    Field[x][gy-Head]=i+1;
  }
}
int kbhit(void)    /* comment */
{
    int ch, r;

    // turn off getch() blocking and echo
    nodelay(stdscr, TRUE);
    noecho();

    // check for input
    ch = getch();
    if( ch == ERR)      // no input
            r = FALSE;
    else                // input
    {
            r = TRUE;
            ungetch(ch);
    }

    // restore block and echo
    nodelay(stdscr, FALSE);
    return(r);
}
int msleep(long msec)
{
    struct timespec ts;
    int res;

    if (msec < 0)
    {
        errno = EINVAL;
        return -1;
    }

    ts.tv_sec = msec / 1000;
    ts.tv_nsec = (msec % 1000) * 1000000;

    do {
        res = nanosleep(&ts, &ts);
    } while (res && errno == EINTR);

    return res;
}

void print()
{
  wchar_t RDC = 0x255D;//right down corner simbol
  wchar_t LDC = 0x255A;//left down corner unicode simbol
  wchar_t VW = 0x2551;//vertical wall simbol
  wchar_t HW = 0x2550;//Horizontal wall simbol
  wchar_t RUC = 0x2557;//right up corner simbol
  wchar_t LUC = 0x2554;//left up corner simbol
  wchar_t HS = 0x2593;
  wchar_t BS = 0x2591;
  wchar_t Frg = 0x1318F;//frog
  // wprintf(L"unicode code  255A prints  %lc\n", LDC);
  // wprintf(L"unicode code 2551 prints %lc\n",VW);
  // wprintf(L"unicode code 2550 prints %lc\n",HW);
  // wprintf(L"unicode code 255D prints %lc\n",RDC);
  // wprintf(L"unicode code 2557 prints %lc\n",RUC);

  // printf ("asscii of 188 gives: %c\n\n",188);
  // printf("%c", 65);
  for (i=0;i<=M+1;i++)
  {
    if(i==0)
    {
      printw("%lc",LUC);
    }
    else if (i==M+1){
      printw("%lc",RUC);
    }
    else{
      printw("%lc",HW);
    }
  }
  printw("\n");
  for(i=0;i<N;i++)
  {
    printw("%lc",VW);
    for (j=0;j<M;j++)
    {
      if(Field[i][j]==0) printw(" ");
      if(Field[i][j]>0&&Field[i][j]!=Head) printw("%lc",BS);
      if(Field[i][j]==Head) printw("%lc",HS);
      if(Field[i][j]==-1) printw("%lc",Frg);
      if(j==M-1) printw("%lc\n",VW);
    }
  }
  for (i=0;i<=M+1;i++)
  {
    if(i==0)
    {
      printw("%lc",LDC);
    }
    else if (i==M+1){

      printw("%lc",RDC);
    }
    else{
      printw("%lc",HW);
    }
  }
}
void ResetScreenPosition(){
  move(0, 0);
}
void Random (){
  srand(time(0));
  a = 1 + rand() % 18;
  b = 1 + rand() % 38;
  if (Frogs == 0 && Field[a][b]==0) {
    Field[a][b] = -1;
    Frogs = 1;
  }
}
long int getch_noblock(){
  if(!kbhit())
    return getch();
  else
    return -1;
}
void movement(){
  var = getch_noblock();
  var = tolower(var);
  if (var == 'd' || var == 'a' || var == 'w' || var == 's') {
    dir=var; 
  }
  if (dir == 'd'){
    y++;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 'a'){
    y--;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 'w'){
    x--;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 's'){
    x++;
    Head++;
    Field[x][y]=Head;
  }
}
int main (int argc, char *argv[]) {
  setlocale(LC_CTYPE, "");
  snakeInitialization();  // moving cursor, x = 20, y = 10
  initscr();
  while (Game == 0) {
    print();
    ResetScreenPosition();
    Random();
    movement();
    msleep(99);
    refresh();

  }
  endwin();
  return 0;
}

and here is the full snake code from the tutorial https://github.com/pawanprjl/Snake-Game-in-C

i thought it could be the kbhit implemetation but i cant figure out. and this is the part of the code that i cant figure out how to make it work as i see in the video

    void movement(){
  var = getch_noblock();
  var = tolower(var);
  if (var == 'd' || var == 'a' || var == 'w' || var == 's') {
    dir=var; 
  }
  if (dir == 'd'){
    y++;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 'a'){
    y--;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 'w'){
    x--;
    Head++;
    Field[x][y]=Head;
  }
  if (dir == 's'){
    x++;
    Head++;
    Field[x][y]=Head;
  }
}

Answer 1

Your getch_noblock function is making a blocking call to getch if kbhit returns zero.

  if(!kbhit())
    return getch();

That would be fine if a zero return-value from kbhit means that there's something to read. But that's not the case.

The "standard" kbhit function returns non-zero when a key-press is available, and zero otherwise. It appears your implementation does, too:

    ch = getch();
    if( ch == ERR)      // no input
            r = FALSE;
    else                // input
    {
            r = TRUE;
            ungetch(ch);
    }

And so your non-blocking read function is broken. This is the correct way:

long int getch_noblock(){
  if(kbhit())
    return getch();
  else
    return -1;
}